europhysicsnews
THE MAGAZINE OF THE EUROPEAN PHYSICAL SOCIETY
SPECIAL ISSUE ON
NUCLEAR FUSION AND PLASMA PHYSICS
Challenges on the road towards fusion electricity
JET, The Largest Tokamak on the eve of DT Operation
The first fusion reactor: ITER
Fusion as a Future Energy Source
A newcomer: The Wendelstein 7-X Stellarator
Low temperature plasma applications in medicine
47/5
47/6
2016
Volume 47 • number 5&6
European Union countries price:
104€ per year (VAT not included)
CONTENTS
europhysicsnews
THE MAGAZINE OF THE EUROPEAN PHYSICAL SOCIETY
SPECIAL ISSUE ON
NUCLEAR FUSION AND PLASMA PHYSICS
Challenges on the road towards fusion electricity
JET, The Largest Tokamak on the eve of DT Operation
The first fusion reactor: ITER
Fusion as a Future Energy Source
A newcomer: The Wendelstein 7-X Stellarator
Low temperature plasma applications in medicine
europhysicsnews
47/5
47/6
2016
Volume 47 • number 5&6
European Union countries price:
104€ per year (VAT not included)
Cover picture: View into the Wendelstein 7-X stellarator during the assembly
of in-vessel components which allow handling heat and particle fluxes to the wall.
Source: Bernhard Ludewig.
EPS EDITORIAL
03 Science denial | C. Rossel
m PAGE 07
Physics Nobel
Prizes 2016
m PAGE 16
Confessions
of a deuteranope
m PAGE 19
Special issue on
Nuclear Fusion
and Plasma Physics
NEWS
04 EPS historic sites: former Institute of Physics,Würzburg University
05 New EPN Science Editor
06 The EPS Edison Volta Prize 2016 awarded to Michel Orrit
07 Physics Nobel Prizes 2016: topology in condensed matter physics
08 Rüdiger Voss is the next EPS President-elect
HIGHLIGHTS
09 Better material insights with gentle e-beams
Better defining the signals left by as-yet-undefined dark matter at the LHC
A new high for magnetically doped topological insulators
10 Arbitrarily slow, non-quasistatic, isothermal transformations
Germanium detectors get position sensitive
11 Improving safety of neutron sources
Surprising neutrino decoherence inside supernovae
12 How cooperation emerges in competing populations
Electron scavenging to mimic radiation damage
Metering the plasma dosage into the physiological environment
13 Polychromatic cylindrically polarized beams
Asymmetrical magnetic microbeads transform into micro-robots
14 The effect of spatiality on multiplex networks
New method helps stabilise materials with elusive magnetism
15 Versatile method yields synthetic biology building blocks
FEATURES
16 Physics in daily life: confessions of a deuteranope | T. Klein
19 Foreword on the special issue on Nuclear Fusion and Plasma Physics | F. Wagner
20 Challenges on the road towards fusion electricity | T. Donné
25 JET, the largest tokamak on the eve of DT operation | L.D. Horton and the JET Contributors
28 The first fusion reactor: ITER | D.J. Campbell
32 Fusion as a future energy source | D.J. Ward
35 A newcomer: the Wendelstein 7-X Stellarator | T. Klinger
39 Low temperature plasma applications in medicine | K.-D. Weltmann, H.-R. Metelmann, Th. von Woedtke
43 Letters to the editors
OPINION
45 Die Energiewende | A. Goede
ANNUAL INDEX
46 Volume 47 - 2016
EPN 47/5&6 01
EPS EDITORIAL
[EDITORIAL]
Science denial
The publication of a controversial
article on the 9/11
collapse of the World Trade
Center buildings in our last issue of
EPN has generated so much interest
and so many downloads that the host
server broke down for a short time. A
first-time experience for our journal.
Some reaction comments are published
in the present issue. This shows
how vivid this dramatic event remains
in our collective memory but also how
quickly the scientific community and
the media can critically react in such a
case. And this is a good thing.
This brings me to the important
issue of science denial, being inspired
by an article by Robert P. Crease in
Physics World of last September
(Phys. World. 29, 9 p. 23, 2016) who
proposes several ways to encourage
a responsible discussion of scientific
issues. He mentions that science denial
is not the product of irrationality
or scientific illiteracy but triggered
more often by political, economic and
religious interests in specific areas of
science such as climate change, energy,
food technology and health. Indeed,
science denial is rather dangerous if
it prevents constructive political decisions
and corrective actions to be taken
by excluding neutral scientific expertise
from these decisions. But even if
science deniers are spreading their
own truth and can be criticized for it,
they cannot be prosecuted with aggressive
means as Suggested by Crease. It
is our role, in an objective scientific
approach to challenge them with the
right arguments and inform policy
makers and politicians accordingly. It
is the unfortunate reality that we live
today in a time when scientific knowledge
often faces organized and strong
opposition by doubters who put the
consensus of experts more openly into
doubt. These controversies are usually
nurtured by their own sources of information
or own interpretations of research
results. 'And there is so much talk
about the trend (of conspiracy) these
days—in books, articles, and academic
conferences—that science doubt itself
has become a pop-culture meme' writes
Joel Achenbach in his article 'Why do
many reasonable people doubt science?'
published in the National Geographic
of March 2015. 'In a sense all this is
not surprising. Our lives are permeated
by science and technology as never before.
For many of us this new world is
wondrous, comfortable, and rich in rewards—but
also more complicated and
sometimes unnerving. We now face risks
we can’t easily analyze.' The complexity
in modelling our atmosphere and predicting
the global warming or the variety
of scenarios for new national energy
policies are the best examples where
furious discussions can take place,
even among reasonable scientists.
I had the opportunity to experience
it myself recently within our EPS Energy
Group. Although such debates
among scientists are part of the traditional
skepticism or critical attitude
in science, the image they propagate
among the public can be rather negative
and counterproductive. I am
convinced that the right behaviour
Science denial
is not the
product of
irrationality
or scientific
illiteracy but
triggered
more often
by political,
economic
and religious
interests in
specific areas
of science
. ©iStockPhoto
is to move forward with courageous
decisions. The slightest possibility of
ignoring grand challenges such as climate
change might jeopardize the future
of our children and grandchildren
without even realizing it.
Interestingly, a catastrophe caused
by climate change is seen as the biggest
potential threat to the global economy
in 2016, according to a survey of 750
experts conducted by the World Economic
Forum (WEF), and published
after the deal signed at the COP21 UN
climate change conference in Paris.
The scientific method is a hard
discipline that leads us to truths
that are less than self-evident, often
mind-blowing, and sometimes hard
to swallow because defying common
sense. We scientists should avoid the
tendency to search for and see only evidence
that confirms what we already
believe. Luckily, peer reviewing of published
scientific studies is not only the
best way to check their validity but also
the best way to foster progress and innovation.
This holds true, even if absolute
certainty does not exist as we move
along the frontiers of knowledge. n
llChristophe Rossel
EPS President
EPN 47/5&6 03
europhysicsnews
2016 • Volume 47 • number 5&6
Europhysics news is the magazine of the European
physics community. It is owned by the European
Physical Society and produced in cooperation with EDP
Sciences. The staff of EDP Sciences are involved in the
production of the magazine and are not responsible for
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Editor: Victor R. Velasco (SP)
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Zsolt Fülöp (Hu), Adelbert Goede (NL), Agnès Henri (FR),
Martin Huber (CH), Robert Klanner (DE),
Peter Liljeroth (FI), Antigone Marino (IT),
Stephen Price (UK), Laurence Ramos (FR),
Chris Rossel (CH), Claude Sébenne (FR), Marc Türler (CH)
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Legal deposit: November 2016
EPS HISTORIC SITES
Former Institute of Physics,
Würzburg University
Röntgenring 8, Würzburg, Germany
The European Physical Society (EPS) has
distinguished the institute where in 1895 Wilhelm
Conrad Röntgen discovered the radiation later
named after him. The building is now the third
"Historic Site" of the EPS in Germany.
London, Paris, Madrid, Rome, Berlin, Munich: Würzburg is now on
a par with these European metropolises. The reasons for this lies in
the history of science: Each of these cities is home to a place that has
been classified as an exceptional "Historic Site" by the European Physical
Society (EPS).
In Würzburg, this site is the former Institute of Physics of the University
of Würzburg on Röntgenring 8. A commemorative board was installed in
front of the building on Röntgenring 8. Unveiled during a ceremonial act, it
documents the significance of the place.
Here Professor of Physics, Wilhelm Conrad Röntgen, discovered the famous
radiation, which was later named after him, in the evening of 8 November
1895. The event was certainly a historic achievement of international
importance: "X-rays have become indispensable in medicine, physics, chemistry
and many other sciences," says University President Alfred Forchel. For
his discovery Röntgen received the first Nobel Prize in Physics in 1901.
. Christophe Rossel (left), President of the European Physical Society (EPS), and University
President Alfred Forchel unveiling the commemorative board. (Photo: Rudi Merkl)
04
EPN 47/5&6
EPS HISTORIC SITES
NEWS
According to Forchel, the weather
during the ceremony, which saw
around 200 invited guests gather at
the historic site, was also worthy of a
Nobel Prize. Forchel was pleased that
the award has made "the connection
of public and science" visible at such
a central spot in the city.
In his opening address, however,
the physicist did not only look back
on Röntgen's ground-breaking discovery,
he also emphasised its impact
for the present: "Röntgen's discovery
has led to the creation of new fields
of business and activity also outside
the scientific context and these are
being developed further dynamically.
Still today, the rays open up wholly
unknown worlds for us.
Christophe Rossel, President of the
EPS, said: "It is wonderful to present
this award at one of the oldest universities
in Europe and Germany." Rossel,
too, underlined the significance of
Röntgen's work for other disciplines,
making the former institute building
a truly historic site for all of science.
The President of Deutsche Physikalische
Gesellschaft took a glimpse at
the imminent next leap in knowledge
"following in Röntgen's footsteps" and
highlighted the great timing of the
awarding. By this, Professor Rolf-Dieter
Heuer was alluding to the start of the
"European XFEL" at the German Electron
Synchrotron (DESY) in Hamburg
planned for 2017. "A top-notch research
facility is being built here."
According to Professor Ralph
Claessen, who followed by delivering
his ceremonial address, this "X-ray
laser" could allow watching chemical
experiments in real-time. And he believes
that this could eventually lead
to more Nobel Prizes being awarded
based on Röntgen's discovery - as already
in around 40 cases at present.
In the first part of his address,
Claessen focused on Röntgen's career.
He highlighted Röntgen's persistence
in pursuing a scientific career despite
several setbacks and the detours he
had to take to arrive there. Röntgen's
actions as university dean were
marked by his great commitment as
was his subsequent time in Munich
where he contributed among others to
the founding of Deutsches Museum.
Claessen also mentioned the rapid
circulation of Röntgen's work under
the title "Eine neue Art von Strahlung"
(On A New Kind Of Rays) which was
rather atypical for the time. Only just
under two weeks passed from the "key
picture" of his wife Anna Bertha's hand
on 22 December 1895 and the unofficial
mailing of his observation to selected
colleagues on New Year's Day until
the first publication by newspapers in
London, Vienna and New York.
Claessen closed his speech by citing
examples from various fields of
art, technology and research that use
X-rays. Among others, X-ray spectroscopy
of van Gogh paintings has
allowed several works of art painted
m Commemorative
board at the
former Institute
of Physics.
Here Wilhelm
C. Röntgen
discovered
the x-rays.
(Photo:
Marco Bosch)
over by the artist himself to be restored
– the colours included. Today
it is common practice in many ports to
scan arriving containers for weapons
and explosives; X-ray astronomy depict
supernovas, forensics determines
the cause of death in deaths long past
and many more.
Claessen finished with a statement
that all attending guests could agree
to: "The former Physical Institute with
Röntgen's study is truly a historic site." n
llRobert Emmerich
Press and Public Relations Office
University of Würzburg
NEW EPN SCIENCE EDITOR
After having served for 8 years as EPN
Science Editor, Prof. Jo Hermans of Leiden
University will leave this position on
January 1 st 2017. Over these 8 years, Jo
has performed invaluable work for the
journal, finding good authors, interesting
and lively features and increasing the
quality of EPN’s issues. Fortunately, Jo will
stay on as part of the Editorial Advisory
Board. We are looking forward to benefiting
from his advice, and in particular his
suggestions for new articles. Of course,
we still expect to publish contributions
from Jo in EPN, for example in the Physics
in Daily Life section.
Thank you, Jo, for your tireless work,
kindness and relentlessly positive attitude,
with our gratitude and best wishes
for your future activities.
The new EPN Science Editor, effective
January 1 st 2017, will be Prof. Ferenc
Iglói of the Wigner Research Centre for
Physics, Budapest. Ferenc has become
familiar with the 'tricks of the EPN trade',
during 2016, by serving as 'Associate
Science Editor', as you will see in this
EPN issue. We warmly welcome Ferenc,
certain that his involvement with EPN
will result in the same high quality output
as for the other scientific journals
he has been associated with. n
Victor R. Velasco, EPN Editor
EPN 47/5
05
NEWS
EPS Edison Volta Prize 2016
The EPS Edison Volta Prize 2016
awarded to Michel Orrit
The EPS, the Fondazione Alessandro Volta and Edison S.p.A. have awarded
the 2016 EPS Edison Volta Prize for outstanding contributions to physics to Michel
A.G. J. Orrit, from Leiden University, the Netherlands "for seminal contributions to
optical science, to the field of single-molecule spectroscopy and imaging (first single
molecule detection by fluorescence and first optical detection of magnetic resonance
in single molecule) and for pioneering investigations into the photoblinking and
photobleaching behaviours of individual molecules at the heart of many current optical
superresolution experiments."
Professor Orrit has made significant
contributions over several
decades to push back the frontiers
of optical physics and spectroscopy.
More than 30 years ago, he produced
very early and highly insightful work
on Langmuir-Blodgett films and spectral
hole-burning in the 1980’s.
After W. E. Moerner’s efforts in
1989 at IBM San José to detect the
optical absorption of a single molecule
of pentacene in p-terphenyl, Prof.
Orrit demonstrated one year later at
the University of Bordeaux that the
optical fluorescence emitted by a single
molecule could be detected with
greatly improved signal-to-noise ratio.
This critical and ground-breaking step
opened the way for many subsequent
investigations of single molecules.
Throughout his career up to the
present, Professor Orrit has shown an
incredible ability to select and conquer
some of the most interesting problems
in modern molecular physics and spectroscopy.
He has been Professor in Molecular
Physics at Leiden University
m Left to right:
S. Zannella,
M. Lucini,
M. Frangi,
M. Orrit,
C. Rossel,
V. Tartamella
. Left to right:
S. Zannella,
M. Frangi,
G. Sapede,
M. Lucini,
M. Orrit,
C. Rossel,
G. Casati
since 2001. He is heading the Molecular
Nano-Optics and Spins Group at the
Leiden Institute of Physics.
EPS Edison-Volta Prize
The EPS Edison Volta Prize promotes
excellence in research and is given in
recognition of outstanding research
and achievements in physics. The
Prize is given biennially to individuals
or groups of up to three people. The
laureates receive a medal, which is a
faithful reproduction of the Medaglia
Premio dell’ Associazione per l’Incremento
del Commercio in Como: a
portrait of Alessandro Volta together
with the saying: Alexandro Voltae
Novocomensi, i.e. (dedicated) to Alessandro
Volta from Novum Comum,
which was the old name given to the
city of Como by Julius Caesar.
The Prize was established in 2011
and was awarded for the first time in
2012 to R. D. Heuer, S. Bertolucci and
S. Myers from CERN, Geneva and in
2014 to J.-M. Raimond from the Laboratory
Kastler Brossel at the Collège
de France, Paris. It was also given to
three principal scientific leaders of the
ESA’s Max Planck Mission in 2015 in
the frame of the International Year of
Light 2015: N. Mandolesi, University
of Ferrara, J.-L. Puget, Institut d'Astrophysique
Spatiale, Université Paris Sud
& CNRS, and J. Tauber, Directorate of
Science and Robotic ESA (NL).
06
EPN 47/5&6
Physics Nobel Prizes 2016
NEWS
Physics Nobel Prizes 2016:
Topology in condensed matter physics
This year's Nobel prize in Physics is given for the discovery of the role of topology in
condensed matter. This subject has seen an explosion of interest in the last decade, but
topology in condensed matter has been studied long before. The prize has been
awarded to pioneering early contributions by David J. Thouless, J. Michael Kosterlitz,
and F. Duncan M. Haldane.
m Left to right: David. J. Thouless, F. Duncan M. Haldane and J. Michael Kosterlit
An early breakthrough mentioned
by the Nobel committee is the
work (in the early 1970's) by Kosterlitz
and Thouless on vortex excitations
in planar spin systems and superfluids [1].
Such vortices are characterized by winding
numbers in real space. Similar winding
numbers, but playing out in momentum
space, are key to the understanding of topological
phases of quantum matter. The Nobel
committee mentions and rewards the
pioneering insight, established by Thouless
and co-workers in the early 1980's, that, miraculously,
momentum space winding numbers
of electronic band structures translate
to quantized values of observables such as
the Hall conductance. These results were
initially applied to quantum Hall systems,
where electrons are constrained to planar
geometry and subjected to a strong perpendicular
magnetic field. A 1988 paper by Haldane[2]
made clear that similar behaviour
arises in a much more general class of systems,
now known as Chern insulators. The
Nobel committee also rewards Haldane's
groundbreaking results on quantum spin
chains, which he published in 1983[3]. In
this work he recognized that chains consisting
of particles with integer spin can form a
topological phase of matter.
Topology in phase transitions
Kosterlitz and Thouless[1] realized the
importance of topology when they studied
what is called the XY model in two
dimensions, a member of a family of
models in d dimensions, with n component
(spin)variables interacting under
full rotational symmetry. The interest
in these models is for the universal
properties of the transition between the
disordered phase at high temperatures,
rotationally symmetric, and an ordered
phase at low temperatures, in which the
spins align along a common direction and
the symmetry is broken.
Kosterlitz and Thouless discovered a
new type of excitation of a topological nature,
called a vortex. A vortex is a localized
excitation, near which the spins on a closed
path surrounding the excitation make one
or more full turns when the path is followed
completely. The number of turns is
called the winding number. The topological
nature of the excitation is reflected in
the impossibility to remove the excitation
by changing the spin values continuously
in space.
A few years before, Mermin and Wagner
had proven that in two dimensions,
a continuous symmetry group like SO(2)
or SO(3) cannot be broken, excluding the
possibility of an ordered phase. Nevertheless
Kosterlitz and Thouless were able to
show the existence of a phase transition
in the XY model. In the low temperature
phase (without long range order) the vortices
form tightly bound pairs of opposite
winding number. In the high- temperature
phase, vortices unbind and move freely
through the system. This transition, now
known as KT transition, had unexpected
characteristics. The singularity in the
free energy is extremely weak, while the
susceptibility diverges stronger than any
power law.
The use of Renormalization theory by
Kosterlitz[4] gave a more complete understanding.
The renormalization transformation
(RT) which acts on the set of
interaction parameters of the system, is
equivalent with changing the spatial scale
of the system. Fixed points of the RT are
thus scale invariant, and correspond to
continuous phase transitions. In contrast,
at the KT transition the whole low-temperature
phase is scale invariant, as it
approaches a line of fixed points under
an RT. KT transitions are found in thin
superfluid films and also in equilibrium
crystal shapes, at the temperature at which
a facet disappears.
Topological phases of matter
Quantum Hall phases and the Haldane
phase of integer-spin quantum chains
are early examples of what are now called
topological phases of matter. A major
conceptual contribution to this field
was made in a 1982 paper by Thouless,
Kohmoto, Nightingale and den Nijs[5].
They used the topological notion of momentum
space winding numbers, known
as Chern numbers, to explain the very
EPN 47/5&6 07
NEWS
Physics Nobel Prizes 2016
precise quantization of the Hall conductance
in a quantum Hall system. The same
reasoning can be applied to more general
systems, including the Chern-insulators
that Haldane introduced in 1988. For the
latter, predictions based on topology were
experimentally verified in thin films of a
topological insulator material (2013) and
in an experiment featuring cold 40 K atoms
in an optical lattice (2014).
A general feature of topological phases
is the presence of gapless excitations at
the edge of the system, or at an interface
between topologically distinct phases. In
the Haldane phase of integer-spin quantum
chains these edge states take the form of
spin-1/2 excitations located at the ends of
the chain.
More recent developments
It has by now been recognized that a multitude
of topological phases of matter are
possible, with details depending on the dimensionality
and on the presence of discrete
symmetries such as particle-hole or
time reversal symmetry.
During the last decade, precise theoretical
predictions have been made for systems
where time reversal symmetry remains
unbroken and protects different types of
topological phases of insulating materials.
In two dimensions such a situation gives
rise to what is called the quantum spin Hall
effect. In three dimensions, topological insulators
protected by time reversal symmetry
have been predicted and observed.
Their edge states are gapless surface states,
with transport properties somewhat akin
to those in materials such as graphene, but
differing from truly two-dimensional materials
in important details.
Perhaps the most spectacular of all phenomena
associated to topological order in
low-dimensional quantum systems is that of
non-Abelian statistics of topological excitations.
In their simplest guise such excitations
take the form of what are called Majorana
zero modes, but more general 'non-Abelian
anyons' have been understood and, to some
extent, classified. Perhaps the simplest systems
where Majorana zero modes are expected
are quantum wire systems designed to be in
the universality class of the so-called 'Kitaev
chain'. The excitement about these developments
derives in part from the perspective of
utilizing non-Abelian anyons for 'topological
quantum computation' - an approach to
quantum computing that uses topology to
safeguard quantum bits from unwanted decoherence.
The experimental situation in this
fascinating domain is developing. There are
indications that the quantum phase underlying
the quantum Hall effect at filling factor
5/2 supports Majorana zero modes, but this
remains to be confirmed experimentally. In
purpose-designed quantum wire setups, signatures
of Majorana zero modes have been
obtained. A demonstration that such excitations
indeed display non-Abelian braid statistics
is eagerly awaited. n
References
llBernard Nienhuis
and Kareljan Schoutens,
Delta Institute for Theoretical
Physics and Institute of Physics
of the University of Amsterdam
[1] J.M. Kosterlitz and D.J. Thouless, J. Phys. C:
(Solid State Physics) 5, L124 (1972),
and J.M. Kosterlitz and D.J. Thouless,
J. Phys. C: (Solid State Physics) 6,1181 (1973).
[2] F.D.M. Haldane, Phys. Rev. Lett. 61, 1988 (2015).
[3] F.D.M. Haldane, Phys. Lett. A 93, 464 (1983) and
F.D.M. Haldane, Phys. Rev. Lett. 50, 1153 (1983).
[4] J.M. Kosterlitz, J. Phys. C: (Solid State Physics)
7(6), 1046 (1974).
[5] D.J. Thouless, M. Kohmoto, M.P. Nightingale,
and M. Den Nijs, Phys. Rev. Lett. 49, 405 (1982).
RÜDIGER VOSS IS THE NEXT EPS PRESIDENT-ELECT
The European Physical Society [EPS] is pleased to announce that Rüdiger
Voss has been elected as the next EPS President-elect. He will take up
office as the President of EPS in April 2017, when the term of the current
President, Christophe Rossel comes to an end.
R. Voss was elected during the Extraordinary Council meeting of the
EPS held on 14 October 2016 at the EPS Secretariat in Mulhouse. It is
noteworthy that Council delegates could participate either in person,
or on-line through the video conferencing system. The EPS welcomed
25 delegates in person and a further 23 attended over the internet.
The Council delegates listened to three inspiring presentations from
the three candidates. The EPS would like to express its heartfelt thanks
to Zsolt Fülöp (HU) and Sydney Galès (FR) who also stood as candidates
for President-elect. Their contributions to the EPS and their vision were
impressive as well.
R. Voss has recently served as Head of International Relations at CERN. In
addition to a successful scientific career at CERN, R. Voss was instrumental
in setting up the SCOAP3 Open Access consortium. n
David Lee, EPS Secretary General
08
EPN 47/5&6
HIGHLIGHTS
Highlights from European journals
MATERIAL SCIENCE
Better material insights
with gentle e-beams
Great potential for a new, more accurate, tool for using
electron collisions to probe matter
There are several ways to change a molecule, chemically
or physically. One way is to heat it; another is to bombard it
with light particles, or photons. A lesser known method relies
on electron collision, or e-beam technology, which is becoming
increasingly popular in industry. In a review outlining new
research avenues based on electron scattering, the authors
. An early 2-D EELS (Electron Energy Loss Spectra) of nitrogen.
explain the subtle intricacies of the extremely brief electron-molecule
encounter, in particular with gentle, i.e., very
low energy electrons. In this paper, which was recently published,
the authors describe how the use of very low energy
electrons and a number of other performance criteria, make
the approach with the so-called Fribourg instrument a more
appealing candidate than previously available tools used to
study electron collisions. One of the potential applications of
this approach is in the quest to find a replacement for a molecule
called sulfur hexafluoride (SF 6 ), a greenhouse gas stored in
high voltage electricity distributing devices, such as switches
and transformers. Electron collision could help identify a more
suitable gas. n
llM. Allan, K. Regeta, J. D. Gorfinkiel, Z. Mašín,
S. Grimme and C. Bannwarth,
'Recent research directions in Fribourg: nuclear dynamics
in resonances revealed by 2-dimensional EEL spectra,
electron collisions with ionic liquids and electronic excitation
of pyrimidine', Eur. Phys. J. D 70, 123 (2016)
PARTICLE PHYSICS
Better defining the signals
left by as-yet-undefined
dark matter at the LHC
New theoretical models that better describe the interaction
between dark matter and ordinary particles advance
the quest for dark matter
m Schematic of an Effective Field
Theory interaction between dark
matter and the standard model.
In the quest for dark matter,
physicists rely on particle colliders
such as the LHC in CERN,
located near Geneva, Switzerland.
The trouble is: physicists
still don't know exactly what
dark matter is. Indeed, they
can only see its effect in the
form of gravity. Until now,
theoretical physicists have
used models based on a simple,
abstract description of the
interaction between dark matter and ordinary particles, such as the
Effective Field Theories (EFTs). However, until we observe dark matter,
it is impossible to know whether or not these models neglect
some key signals. Now, the high energy physics community has
come together to develop a set of simplified models, which retain
the elegance of EFT-style models yet provide a better description
of the signals of dark matter, at the LHC. These developments are
described in a review published by the authors.n
llA. De Simone and T. Jacques,
'Simplified models vs. effective field theory approaches in
dark matter searches', Eur. Phys. J. C 76, 367 (2016)
CONDENSED MATTER
A New High for Magnetically
Doped Topological Insulators
Surface phenomena in ring-shaped topological insulators
are just as controllable as those in spheres made of
the same material
Topological insulators (TIs) are a new phase of quantum matter
whose conducting surface states are a result of the topology
of their bulk band structure. Their spin-momentum locked
EPN 47/5&6 09
HIGHLIGHTS
from european journals
m Temperature dependence of the magnetization, M(T), of Cr x Sb 2-x Te 3 thin film
samples with varying Cr concentration, x. The most highly doped and structurally
uncompromised film shows a transition temperature of 125 K.
topological surface states are resilient to backscattering owing
to their protection by time-reversal symmetry (TRS). These
properties make them intriguing candidates for low-power
devices, spintronics and quantum computation. Breaking TRS
by introducing magnetic dopants, and introducing a gap in
the topological surface states, unlocks exotic quantum phenomena
such as the quantum anomalous Hall state. Doping
TIs with magnetic impurities is an experimentally challenging
process and most TI materials only exhibit magnetic ordering
at low temperatures.
In this study, using a variety of complementary structural,
electronic and magnetic characterisation techniques, we
demonstrate the synthesis of magnetically doped TI thin films
with high structural quality. The Cr-doped Sb 2 Te 3 thin films were
grown on sapphire using low-temperature molecular beam
epitaxy. We show that this particular system exhibits uniform
ferromagnetic ordering up to ~125 K – a step forward towards
device-friendly TI materials. n
llL. J. Collins-McYntire + 13 co-authors
'Structural, electronic, and magnetic investigation of
magnetic ordering in MBE-grown Cr x Sb 2-x Te 3 thin films',
EPL 115, 27006 (2016)
STATISTICAL PHYSICS
Arbitrarily slow, non-quasistatic,
isothermal transformations
free expansion therefore
requires work.
Here, the authors explore
experimentally the origin
of thermodynamic irreversibility
at the level of
a single-particle “gas”. A
feedback trap confines a
silica particle in a virtual
bistable potential, creating
a system analogous
to two vessels connected
by a valve, where the
volume of one vessel is
adjustable via piston. The
authors operate two types of cyclic transformations; both start
and end in the same equilibrium state, and both use the same
basic operations—but in different order. One transformation
required no work, while the other required work, no matter
how slowly it was carried out.
Why the difference? As the illustration shows, the result of
carrying out a protocol backwards in time may not match the
initial state. This property is not possible to notice in a single
repetition, unlike in a macroscopic system where free expansion
is followed by a “whoosh”. n
llM. Gavrilov and J. Bechhoefer,
'Arbitrarily slow, non-quasistatic, isothermal transformations',
EPL 114, 50002 (2016)
NUCLEAR PHYSICS
Germanium detectors
get position sensitive
m A thermodynamically irreversible cycle
for single-particle and classical engines.
High purity germanium detectors have grown into very popular
devices within the field of gamma ray spectroscopy. The
sensitive part of these detectors consists of the largest, purest
and monocrystalline semi-conductors used on earth. Ge
detectors are famous for their outstanding energy resolution
for electromagnetic radiation, especially in the field of nuclear
. Interaction positions determined by the pulse shape analysis of AGATA and the
AGATA spectrometer at GANIL” (picture by P. Lecomte)
Joule or free expansion of an ideal gas into a volume at lower
pressure is an example of an irreversible isothermal process.
This nonequilibrium example is often used in thermodynamics
texts to demonstrate that an arbitrarily slow process need
not be reversible. Cyclic operation of engines that involve a
10 EPN 47/5&6
from european journals
HIGHLIGHTS
physics and astrophysics. Recently technical advances and the
segmentation of the Ge crystals opened up new opportunities.
In this way, the Ge detector becomes a position sensitive device
and allows for the novel gamma-ray tracking technique.
New gamma ray spectrometers are currently under construction
and implement the new method. The article describes all
the theoretical concepts, which are needed for a precise understanding
of all detector properties. Moreover, an elaborate
computer code, named ADL, was developed and yielded a huge
set of hundred thousands of detector pulses. These pulses are
compared to measured pulses from individual gamma rays in
order to extract the position where the radiation interacted
with the detector material and created charges. ADL utilizes all
relevant aspects of signal creation and formation with the Ge
detector and the subsequent electronics. Meanwhile the code
is successfully used for position sensitive spectroscopy within
the AGATA project. n
llB. Bruyneel, B. Birkenbach and P. Reiter,
'Pulse shape analysis and position determination in segmented
HPGe detectors: The AGATA detector library', Eur.
Phys. J. A 52, 70 (2016)
do not always understand the mechanism of residue nuclei
production, which can only be identified using spectrometry
methods to detect their radioactive emissions. In a new study
examining the radionuclide content of lead-bismuth-eutectic
(LBE) targets, the authors found that some of the radionuclides
do not necessarily remain dissolved in the irradiated targets.
Instead, they can be depleted in the bulk LBE material and accumulate
on the target's internal surfaces. These findings have
recently been published. The results improve our understanding
of nuclear data related to the radionuclides stemming from
high-power targets in spallation neutron sources. They contribute
to improving the risk assessment of future high-power
spallation neutron beam facilities — including, among others,
the risk of erroneous evaluation of radiation dose rates. n
llB. Hammer-Rotzler, J. Neuhausen, V. Boutellier,
M. Wohlmuther, L. Zanini, J.-C. David, A. Türler and
D. Schumann,
'Distribution and surface enrichment of radionuclides in
lead-bismuth eutectic from spallation target', Eur. Phys. J.
Plus 131, 233 (2016)
NUCLEAR PHYSICS
Improving safety
of neutron sources
Testing liquid metals as target material bombarded by
high-energy particles
NUCLEAR PHYSICS
Surprising neutrino
decoherence inside supernovae
Theory to explain collective effects of neutrinos inside
supernovae strengthened
There is a growing interest in the scientific community in a
type of high-power neutron source that is created via a process
referred to as spallation. This process involves accelerating
high-energy protons towards a liquid metal target made of
material with a heavy nucleus. The issue here is that scientists
. Sampling of Lead-Bismuth-eutectic material/cover gas-interface sample
consisting of solid material forming a powdery crust onto the steel wall.
m Illustration of the shift of two wave packets with large spread. Loss of coherence
occurs even if the packets overlap due to the spatial energy redistribution within
the whole wave packets.
Neutrinos are elementary particles known for displaying weak
interactions. As a result, neutrinos passing each other in the
same place hardly notice one another. Yet, neutrinos inside a
supernova collectively behave differently because of their extremely
high density. A new study reveals that neutrinos produced
in the core of a supernova are highly localised compared
to neutrinos from all other known sources. This result stems
from a fresh estimate for an entity characterising these neutrinos,
known as wave packets, which provide information on
both their position and their momentum. These findings have
just been published by the authors. The study suggests that
EPN 47/5&6 11
HIGHLIGHTS
from european journals
the wave packet size is irrelevant in simpler cases. This means
that the standard theory for explaining neutrino behaviour,
which does not rely on wavepackets, now enjoys a more sound
theoretical foundation. n
llJ. Kersten and A. Yu. Smirnov,
'Decoherence and oscillations of supernova neutrinos',
Eur. Phys. J. C 76, 339 (2016)
COMPLEX SYSTEMS
How cooperation emerges
in competing populations
New theoretical approach to understand the dynamics
of populations reaching consensus votes or of spreading
epidemics
m The fraction of cooperative players as a function of the site-occupancy
probability ρ obtained using numerical simulations.
ATOMIC AND MOLECULAR PHYSICS
Electron scavenging to mimic
radiation damage
New study could help unveil negative effect of radiation
on biological tissues due to better understanding of low
energy electron-induced reactions
High energy radiation affects biological
tissues, leading to short-term
reactions. These generate, as a secondary
product, electrons with low
energy, referred to as LEEs, which
are ultimately involved in radiation
damage. In a new study, scientists
study the effect of LEEs on a material
F3C
called trifluoroacetamide (TFAA). This material was selected because
it is suitable for electron scavenging using a process known
as dissociative electron attachment (DEA). These findings were recently
published, as part of a topical issue on Advances in Positron
and Electron Scattering. Experiments confirm that DEA reactions
occur due to electrons entering unoccupied molecular orbitals,
at an energy level located near one electronvolt. This means that
low-energy electrons can be exploited with solid materials like
TFAA to trigger selective reactions, resulting in multiple bond cleavages
inside the material. Ultimately, this leads to the creation of
specific negative ions and stable molecules of interest. n
llJ. Kopyra, C. König-Lehmann, E. Illenberger,
J. Warneke and P. Swiderek,
'Low nergy electron induced reactions in fluorinated
acetamide – probing negative ions and neutral stable
counterparts', Eur. Phys. J. D 70, 140 (2016)
O
NH2
m Molecule of
trifluoroacetamide (TFAA).
Social behaviour like reaching a consensus is a matter of cooperation.
However, individuals in populations often spontaneously
compete and only cooperate under certain conditions. These
problems are so ubiquitous that physicists have now developed
models to understand the underlying logic that drives competition.
A new study published recently shows the dynamics of
competing agents with an evolving tendency to collaborate that
are linked through a network modelled as a disordered square
lattice. These results are the work of the authors. They believe
that their theoretical framework can be applied to many other
problems related to understanding the dynamical processes in
complex systems and networked populations, such as the voter
dynamics involved in reaching a consensus and spreading dynamics
in epidemic models and in social networks. n
llC. Xu, W. Zhang, P. Du, C.W. Choi and P.M. Hui,
'Understanding cooperative behaviour in structurally
disordered populations', Eur. Phys. J. B 89, 152 (2016)
BIOPHYSICS
Metering the plasma
dosage into the physiological
environment
There is significant optimism that cold atmospheric (ionised
gas) plasma could play a role in the treatment of life-threatening
diseases, such as non-healing chronic wounds and cancers.
The medical benefits from plasma are thought to arise from
the reactive oxygen and nitrogen species (RONS) generated
by plasma upon interaction with air and liquids. However, it
is unclear what RONS are delivered by plasma into tissue fluid
and tissue, and their rate of delivery. This knowledge is needed
to develop safe and effective plasma therapies.
In this investigation, a simple approach was proposed to
monitor the dynamic changes in the concentrations of RONS
12 EPN 47/5&6
from european journals
HIGHLIGHTS
m Plasma therapy.
m Various polarization patterns (arrows) and intensity distributions (underlying
doughnut) of a co-rotating radially polarized X-wave.
and dissolved oxygen within tissue-like fluid and tissue during
plasma treatment. A plasma “jet” device was shown to non-invasively
transport RONS and oxygen deep within tissue (to
millimetre depths). However, tissue fluid directly treated with
the plasma jet was deoxygenated due to the gas flow purging
oxygen out of the fluid.
Monitoring and controlling the plasma delivery of both
RONS and oxygen into tissue fluid and tissue is necessary to
avoid hypoxia in open wound treatment, to achieve targeted
destruction of cancerous cells within solid tumours and to oxygenate
oxygen-starved tissue to stimulate tissue regeneration. n
llJ.-S. Oh, E. J. Szili, N. Gaur, S.-H. Hong, H. Furuta,
H. Kurita, A. Mizuno, A. Hatta and R. D. Short,
'How to assess the plasma delivery of RONS into tissue
fluid and tissue', J. Phys. D 49, 304005 (2016)
OPTICS
Polychromatic cylindrically
polarized beams
Cylindrically polarized beams represent a class of solutions,
where the polarization can be radially or azimuthally distributed
across the intensity profile. These beams have very intriguing
properties, both from a fundamental and an applied
perspective. Despite their great success, they have been almost
exclusively studied and realized within the monochromatic
regime.
An open question is if non-monochromatic cylindrically
polarized solutions of Maxwell equations exist. New research
answers to this question by employing X waves with orbital
angular momentum (the polychromatic counterpart of Bessel
beams) as building blocks to generate optical pulses with radial
and azimuthal polarization. This approach is different from
the monochromatic case where Hermite-Gaussian beams are
typically used. Solutions are investigated in the paraxial and
the nonparaxial regime and the role of the pulse’s spectrum
in the polarization properties of the pulse itself is pointed out.
Analysis shows that the generalization of the concept of
non-uniform polarization to the domain of optical pulses leads
to new intriguing applications, such as spatially resolved Raman
spectroscopy. Cylindrically polarized X-waves with orbital angular
momentum could also open new intriguing scenarios for
fundamental research and quantum optics. n
llM. Ornigotti, C. Conti and A. Szameit,
'Cylindrically polarized nondiffracting optical pulses',
J. Opt. 18, 075605 (2016)
CONDENSED MATTER
Asymmetrical magnetic
microbeads transform
into micro-robots
Thanks to the ordering effects of two-faced magnetic
beads, they can be turned into useful tools controlled by
a changing external magnetic field
Janus was a Roman god with two distinct faces. Thousands of
years later, he inspired material scientists working on asymmetrical
microscopic spheres—with both a magnetic and a
non-magnetic half—called Janus particles. Instead of behaving
like normal magnetic beads, with opposite poles attracting,
Janus particle assemblies look as if poles of the same type attract
each other. A new study reveals that the dynamics of such
assemblies can be predicted by modelling the interaction of
only two particles and simply taking into account their magnetic
asymmetry. These findings were recently published by
EPN 47/5&6 13
HIGHLIGHTS
from european journals
m Transformation of particle clusters while exposed to an oscillating external
magnetic field.
the authors. It is part of a topical issue entitled "Nonequilibrium
Collective Dynamics in Condensed and Biological Matter." The
observed effects were exploited in a lab-on-a-chip application
in which microscopic systems perform tasks in response to a
changing external magnetic field, such as, for instance, to create
a zipper-style micro-muscle on a chip. n
llG. Steinbach, S. Gemming and A. Erbe,
'Non-equilibrium dynamics of magnetically anisotropic
particles under oscillating fields', Eur. Phys. J. E 39, 69 (2016)
COMPLEX SYSTEMS
The effect of spatiality
on multiplex networks
paper, we use this to modulate the strength of spatial effects on
network topology. This allows us to consider the question: Does
increasing the allowed geometric length of links in a network
improve its robustness? In single-layer networks, the answer is
generally that it does. However, in multiplex networks, we find
that increasing the link lengths actually makes the network
vulnerable to more severe cascade behaviours. This is because
in multiplex networks, longer links allow for a discontinuous
percolation transition which is characterized by a nucleation
process. Our model and results demonstrate the surprising effects
of spatial embedding and provide a simple new framework
for assessing spatial networks of one or more layers. n
lM.M. l Danziger, L.M. Shekhtman, Y. Berezin and S. Havlin,
'The effect of spatiality on multiplex networks', EPL 115,
36002 (2016)
MATERIAL SCIENCE
New method helps
stabilise materials with
elusive magnetism
Stabilising materials with transient magnetic characteristics
makes it easier to study them
When a node can only form a link to its nearest neighbour,
the topology is entirely determined by the spatial locations of
the nodes. But when near and far links can form, the influence
of the spatial embedding of the topology is much less. In this
. The multiplex structure arising from beginning with nodes on a lattice and
connecting them through two layers of links (gray and black) with the length of
each link following an exponential distribution.
m Visualisation of itinerant ferromagnetic domains.
Magnetic materials displaying what is referred to as itinerant ferromagnetism
are in an elusive physical state that is not yet fully
understood. They behave like a magnet under very specific conditions,
such as at ultracold temperatures near absolute zero.
Realising the itinerant ferromagnetic state experimentally using
ultracold gas is a challenging undertaking. This is because when
three atoms - one with the opposite spin of the other two - come
close to each other two atoms with opposite spin will form
molecules and the other one carries the binding energy away;
a phenomenon called rapid three-body recombination. Now,
the authors, have introduced two new theoretical approaches
to stabilise the ferromagnetic state in quantum gases to help
14 EPN 47/5&6
from european journals
HIGHLIGHTS
study the characteristics of itinerant ferromagnetic materials.
The first approach involves imposing a moderate optical lattice.
There, the three-body recombination is small enough to permit
experimental detection of the phase. In a second approach, they
suggest to prepare two initially separated clouds and study their
time evolution. The ferromagnetic domains has longer life time
because of the reduced overlap region between the two spins.
These results were recently published. n
llI. Zintchenko, L. Wang and M. Troyer,
'Ferromagnetism of the repulsive atomic Fermi gas: threebody
recombination and domain formation', Eur. Phys. J.
B 89, 180 (2016)
BIOPHYSICS
Versatile method yields
synthetic biology building blocks
New high-throughput method to produce both liposomes
and polymersomes on the same microfluidic chip
Synthetic biology involves creating artificial replica that mimic
the building blocks of living systems. It aims at recreating biological
phenomena in the laboratory following a bottom-up approach.
Today scientists routinely create micro-compartments,
so called vesicles, such as liposomes and polymersomes. Their
membranes can host biochemical processes and are made of
self-assembled lipids or a particular type of polymers, called
block copolymers, respectively. In a new study, researchers have
developed a high-throughput method--based on an approach
known as microfluidics--for creating stable vesicles of controlled
size. The method is novel in that it works for both liposomes
and polymersomes, without having to change the design of
the microfluidic device or the combination of liquids. The authors
recently published these findings. Typical applications
m Fluorescence microscopy image of polymersomes, taken 3 days after production.
in synthetic biology include the encapsulation of biological
agents and creation of artificial cell membranes with a specific
biochemical function. They anticipate that their method might
also be applicable for the controlled fabrication of hybrid vesicles
used in bio-targeting and drug-delivery. n
llJ. Petit, I. Polenz, J.- C. Baret, S. Herminghaus
and O. Bäumchen,
'Vesicles-on-a-chip: A universal microfluidic platform for
the assembly of liposomes and polymersomes', Eur. Phys. J.
E 39, 59 (2016)
NOMINATIONS FOR EDITOR IN CHIEF OF EPL
Nominations are now open for the
Editor-in-Chief of EPL, a leading global
letters journal owned and published
by a consortium of 17 national physical
societies in Europe. The Editor-in-Chief
(EiC) needs to be a recognized authority
and leading researcher in a field of
physics, and have a broad knowledge
and interest in physics and its frontiers.
The EiC will need to demonstrate strong
commitment and leadership to further
develop EPL as a top-ranking journal.
Experience with the editorial process for
a physics journal is also desirable. The
EiC is central to enhancing EPL’s position
as a leading global physics letters
journal. The term of office of EPL Editor-in-Chief
is three and a half years beginning
in July 2017. A job description is
available at https://www.epletters.net.
Nominations must include a CV, publication
list, and a brief covering letter
describing the qualifications and the interest
of the individual in the position
of EPL Editor-in-Chief. Nominations
should be sent to the EPL Editorial
Office no later than 15 January 2017
(editorial.office@epletters.net).
Further information can be obtained
from the Editorial Office in Mulhouse. n
EPN 47/5&6 15
[Physics in daily life]
by Tony Klein
School of Physics – The University of Melbourne, Australia - http://dx.doi.org/10.1051/epn/2016501
Confessions of a deuteranope
About 8% of men – but only about 0.6% of
women – among us exhibit Colour Vision
Deficiency (CVD), i.e., are said to be colour
blind. This genetic defect, by the way, is called
“Daltonism” in French, named after John Dalton the noted
chemist, who was one of its more notorious sufferers and
generators of anecdotes.
The most common form of colour blindness, called
red-green colour blindness, is caused by a defect on the X
chromosome, of which males have only one copy, whereas
females, who have two copies may be protected by the other
X chromosome if it has a non-defective gene. However one
half of their male offspring will be afflicted and thus they are
“carriers”. In my case, I inherited my colour blindness from
my maternal grandfather, and my grandson got it from me,
via my daughter, who has perfect colour vision. Half my
daughters and my grand-daughters, are likely to be carriers.
So, what is this defect? As is well known, there are two
types of light receptor cells in the human retina: rods and
cones. It is the cones that are responsible for colour vision;
the more abundant rods are extremely sensitive to light but
only give black-and-white information for night-vision
(and information on motion and edge detection in brighter
light). By the way, recent experiments have shown that one
single photon is capable of triggering the receptors, provided
that they have escaped capture by intervening tissue.
There are three types of cones, responsive to short, medium
and long (i.e. S, M and L) wavelengths of visible light,
but actually they have three different spectral sensitivities,
as shown in Fig.1.
In a somewhat simplified explanation, if one of the M
or S cones is missing (or has a much reduced abundance)
in a person’s retina, they will be a so-called “dichromat” or
colour blind: “green-blind” or “deuteranope” (like I am) if
missing the M cones; “red-blind”, or “protanope” if missing
L cones; “blue-blind”, or “tritanope” in the rare case of
missing the S cones.
m FIG.1: Spectral Sensitivities of the three types of cone cells.
What does this mean in practice? In the case of protanopes,
they cannot see red traffic lights or only very dimly,
and can’t see red flowers very well at all. In my case, I see
grass etc. as some shade of brown – but it’s really more complicated
than that. Our world is still full of colour – around
10,000 different hues, in fact, whereas people with normal
colour vision can see about 1,000,000. I do, however, have
trouble with red flowers having very low contrast with the
surrounding green leaves in certain beautiful trees like the
“flame tee” or Poinciana. Often I can’t see them until up
close. But I have no trouble at all with traffic lights: The
“green” is really very bluish.
It’s a bit like a colour printer with one of the cartridges
missing, but not really: The Cyan, Yellow, Magenta system
of colour printing is quite different from the Short,
Medium, Long cones in the retina, but each system has in
common a triple manifold of colours, i.e., needing three
numbers to specify a hue. I found a better set of examples in
Wikipedia, while researching this column. Under “Colour
Blindness” (which tells you more about the subject than
you might wish to know) there are pairs of pictures that
show what a normal and a red-green blind person would
see. In spite of the limitations of the computer screen or
. FIG. 2a: Normal vision . FIG. 2b: Deuteranopic vision . FIG.2c: Tritanopic vision.
© www. rehue.com
16 EPN 47/5&6
Physics in daily life SECTION
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high-technology research laboratories
and industrial development sites. Zurich
Instruments' vision is to revolutionize
instrumentation in the high-frequency
and ultra-high-frequency
range by incorporating
the latest analog and digital
technology into powerful
measurement systems.
The EPS is not responsible for the content of this section.
EPN 47/5&6 17
[Physics in daily life]
(a)
(b)
m FIG. 3: (a) normal and (b) deuteranope vision.
of the printed page, they look pretty good to me: I can’t tell
the difference! If you, the reader can’t either, then you may
be part of the 8% (if male) or the 0.6% (if female) – join
the “club”. The pictures are shown in Figs. 2a, and 2b and
for the sake of completeness 2c: Tritanopic vision, the rare
condition of missing the S cone.
A very interesting issue concerns colour vision in animals:
It turns out that most animals (except insects) have
no colour vision at all. However, birds, reptiles and amphibians
(as well as some rare human females), can have four
different cone types. But it turns out that most mammals
are deuteranopes, i.e., green blind – so people like me are
by no means alone. And more recent research shows that
the third type of cone has evolved rather more recently in
(old-world) monkeys and presumably humans and other
fruit-eaters in order to distinguish ripe fruit. This is illustrated
in Fig. 3: Red and green apples as they appear to
normals (a) and deuteranopes (b). Once again, I can’t tell
the difference!
So what sort of handicap is colour blindness and how
is it diagnosed? In my case, at around the age of 3, it was
found by my mother that I was using “crazy” colours in
colouring books, e.g. ships sailing on violet seas instead
of blue. She knew that her father had trouble with colours
but they all thought that he had trouble naming colours
because they didn’t understand the concept of CVD. But
to me it represented hardly any handicap in perceiving the
wonderfully coloured world.
Much later, however, as a teenager, I was chucked out of
flying school (much to the relief of my parents) when my
CVD was properly diagnosed. This was done by the use
of the most common test, the one named after its promulgator,
Professor Ishihara. (Several other tests exist for
other, more subtle types of CVD). The Ishihara test consists
of subtly coloured dots showing numbers hidden among
other coloured dots. The perceived numbers are different
for normal and colour blind subjects. An example of one
such test pattern is showed in Fig. 4:
Apart from being prohibited from certain occupations
such as piloting or train-driving, I have hardly felt any
handicap apart from a few incidents with colour-coded
wires and electronic components. But otherwise it was
more of a source of amusement, such as when a cousin and
I (who shared a common maternal grandfather) marvelled
at a rare Australian orange-bellied parrot, which turned out
to have been bright green. But we had no trouble at all with
other more common (Australian) coloured birds, such as
rainbow lorikeets and rosellas which are, to us, bright red
and what we see as nearest thing to bright green. n
b FIG. 4: Example
of an Ishihara test
plate. People with
normal colour vision
see the number 74;
I, a deuteranope, see
the number 21 or
81. Protanopes see
other numbers, or
simply can’t tell.
Acknowledgement
The author is very grateful to Dr Jessica Kvansakul, whose
PhD was in the area of vision science, and whose normal
colour vision allowed her to make significant improvements
to the text and to the illustrations. She is the Editor of “Australian
Optical Society News” where this article originally
appeared.
About the author
Professor Emeritus Tony Klein held a
Personal Chair in Physics in the University
of Melbourne until his retirement
in 1998. He served as President of the
Australian Optical Society (1985-86);
President of the Australian Institute
of Physics (1990 – 91); Head of the School of Physics
(1986 –95). He was elected a Fellow of the Australian
Academy of Science in 1994 and was appointed a Member
of the Order of Australia in 1999. He has published
extensively in experimental physics, particularly about
neutron optics, including focusing of neutrons with a
Fresnel Zone Plate.
18 EPN 47/5&6
FEATURES
FOREWORD
ON THE SPECIAL ISSUE
ON NUCLEAR FUSION
AND PLASMA PHYSICS
FROM THE EDITORS
It is with great pleasure that we present this special issue on
Nuclear Fusion and Plasma Physics. The topic in this issue
is both important and timely. Important because Fusion has
the potential to provide mankind with a nearly unlimited
source of energy. Timely, because this year has witnessed
a breakthrough in this field at the Max Planck Institute for
Plasma Physics in Greifswald, where the Wendelstein 7-X
fusion device produced its first hydrogen plasma. We are
proud and grateful that former EPS President Fritz Wagner,
one of the pioneers in this field, was willing to act as a Guest
Editor for this special issue. It is Fritz and his authors who
should have the credit of this issue, which we hope will provide
most interesting reading.
Victor R. Velasco, Jo Hermans and Ferenc Iglói
FROM THE GUEST EDITOR
The technologies which have been developed in the last centuries
and which are powered by cheap energy allowed mankind to grow
to more than 7 billion people on earth and produced regions with
till then unknown wealth. Such an area is Europe.
Our lifestyle seems to be endangered now because
fossil fuels come to an end. It is not such that the
wells were empty rather the atmosphere is full, full
of CO 2 , and the earth is at the brink of overheating.
Disregarding carbon capture and sequestration
mankind has three choices of a CO 2 -free energy
supply: fission, fusion and renewable energies.
In this special issue we present the status of fusion
research and development. The principle of fusion
is based on the processes in our sun and the stars which fuel the
universe. Fusion research has been started after WWII and is now
pursued in most industrialized countries. The original hopes have
not been fulfilled to master this technology on short notice. The
popular joke – when asked, the realization of fusion always takes
40 years – goes back to a roadmap which has been developed after
the first energy crisis in the seventies of last century. The fusion
community responded with a schedule and financial plan. The
financial support collapsed as soon as the crisis was over. Probably,
Lev Artsimovich, a Russian fusion pioneer, was right when he
expected that fusion will be developed when mankind needs it.
The time has come now and the first experimental fusion reactor,
ITER, is under construction in France.
This special issue describes how fusion research in Europe has
responded in its organization and in its technical and scientific
objectives since the ITER decision has been taken. The tenor of
the individual papers reflects these changes because
much more technology, material and safety issues
are addressed. The orientation of the scientific programs
e.g. those of JET, the world-wide largest fusion
device in England, is strictly oriented toward
the needs of ITER. Objectives and status of ITER are
presented in detail. In a separate paper the final step
to a demonstration reactor, DEMO, is described discussing
operational safety, waste, electricity costs and
market penetration of this technology. A new device
has started operation in northern Germany, Wendelstein 7-X. This
device is not a tokamak like JET and ITER but a stellarator based
on a completely novel concept. The ideas behind this concept and
the goals of W7-X along with the arguments to pursue two representatives
of toroidal magnetic confinement are presented in detail.
Fusion research with magnetic confinement is only one application
of plasma physics. It is impossible to cover this large
field by a special issue. Just to give the reader one example of a
totally different application of plasma physics we have added a
paper on the use of plasmas in medicine. We selected this paper
because two of its authors received the 2016 EPS Plasma Physics
Innovation Prize. n
Fritz Wagner
EPN 47/5&6 19
FEATURES
CHALLENGES ON THE ROAD
TOWARDS FUSION ELECTRICITY
llTony Donné – DOI: http://dx.doi.org/10.1051/epn/2016502
llEUROfusion Programme Management Unit, Boltzmannstraße 2, 85748 Garching bei München, Germany
The ultimate aim of fusion research is to generate electricity by fusing light atoms
into heavier ones, thereby converting mass into energy. The most efficient fusion
reaction is based on merging the hydrogenic isotopes: Deuterium ( 2 D) and Tritium
( 3 T) into Helium ( 4 He) and a neutron, which releases 17.6 MeV in the form
of kinetic energy of the reaction products.
20 EPN 47/5&6
fusion electricity
FEATURES
The helium particle carries 20% of the reaction
energy which is used for heating the plasma.
The neutron with 80% of the energy is not
confined by the magnetic field and will penetrate
into the blanket surrounding the plasma. There
it deposits its energy, leading to a temperature rise of
the blanket coolant, which will drive electric turbines.
In the blanket it also converts 6 Li into 3 T and 4 He; the 3 T
is subsequently used as fuel.
The two main strategies to achieve fusion on Earth
are based on magnetic confinement and inertial confinement.
In magnetic confinement, a gas is heated to
temperatures in the order of 1 - 1.5 × 10 8 K. At these
high temperatures the gas has transformed into plasma,
consisting of charged particles with sufficiently high energy
to overcome the Coulomb potential and to fuse.
. Magnetic field lines
in the Wendelstein
7-X stellarator in
Greifswald, made
visible by the
combination of an
electron gun and
a fluorescent rod
moved through the
vacuum vessel.
Magnetic fields are used to confine the plasma and keep it
away from any material surfaces. In inertial fusion a small
pellet of solid deuterium-tritium is quickly and strongly
compressed by powerful laser or particle beams, leading
to sufficiently high densities and temperatures for fusion.
Magnetic Confinement Fusion
European fusion research is largely concentrated on magnetic
confinement fusion, as it is the most promising concept
to deliver fusion electricity. In the range of magnetic
confinement devices that have been studied over the last
decades, the tokamak has reached the best performance. In a
tokamak, the plasma is confined by a magnetic field that is a
superposition of a field generated by external magnetic coils
(yielding a field in the toroidal direction) and an internal
poloidal field generated by a toroidal current through the
plasma which is induced by a transformer (see Figure 1).
Hitherto, the highest fusion performance (16 MW) has
been achieved in the Joint European Torus, JET, world’s largest
tokamak (see article by L. Horton). Also the international
ITER experiment (see article by D. Campbell) – a collaboration
of China, Europe, India, Japan, Russia, South-Korea
and the United States – is based on the tokamak concept.
ITER is expected to have first plasma around the middle
of the next decade and is designed to achieve fusion power
generation of about 500 MW, using 50 MW of external input
power. ITER will not deliver any fusion electricity and will
therefore be succeeded by DEMO, the first Demonstration
Fusion Power Plant (see article by D. Ward).
EUROfusion and the European
Fusion Roadmap
Europe has drafted an elaborate plan to achieve the milestone
of fusion electricity demonstration in DEMO by the
middle of the century. In this so-called Fusion Roadmap,
eight important missions have been defined, which can
be grouped into:
1. Risk mitigation for ITER
2. (Pre-) Conceptual Design of DEMO
3. The stellarator as back-up strategy
Fusion research in Europe is coordinated by EUROfusion,
a consortium of 29 National Fusion Laboratories
from 27 countries, plus Switzerland and – from 2017 onwards
- Ukraine, along with over 100 Universities, groups
and industries that are acting as Linked Third Parties to
the National labs (see Fig. 2).
The fusion community is confident that ITER will
work and reach its full performance and all of its objectives.
However, there are open research issues that, if
better understood, can help ITER to optimise its research
plan. It is no surprise that there are even more open issues
with respect to the design of the DEMO reactor. These are
largely related to the very hostile environment with strong
plasma-wall interaction and high fluxes and fluences of
EPN 47/5&6 21
FEATURES
fusion electricity
neutrons and gammas emerging from the hot plasma.
In the remainder of this paper and the following ones of
this special issue the reader will be guided through a few
of the main physics challenges in the fusion roadmap.
The choice has been made to focus on items 1 and 3
above. Item 2 is linked to the DEMO design and preparation,
and is more technology-oriented than the other two
items, although it comprises challenging and interesting
issues such as developing neutron-resistant materials,
achieving tritium self-sufficiency, intrinsic safety, integrated
DEMO design and competitive cost of electricity
(see article by D. Ward).
Risk mitigation for ITER (and DEMO)
The temperature of the fusion plasma in ITER (and also
in DEMO) must be about 10-20 times higher than that
in the core of the Sun, for colliding particles to have sufficient
energy to fuse. Because there are strong temperature-,
density- and current density gradients, the plasma is
prone to develop microscopic instabilities (turbulence) as
well as macroscopic magnetohydrodynamic instabilities,
which degrade the plasma performance. The macroscopic
instabilities can potentially completely destabilise a
tokamak plasma which can end the plasma state. This
process - called disruption - leads to strong forces onto
the surrounding vacuum vessel due to induced halo currents.
So plasma scenarios need to be developed in which
the performance is ramped up in a controlled way and
in which instabilities are actively controlled. An excellent
external ‘knob’ to control magneto-hydrodynamic
instabilities is the injection of radio waves at the place
of the instability. The radio frequency waves injected are
either resonant with the local electron or ion cyclotron
frequency or one of its higher harmonics. This stabilisation
method can act either on the electrons or on the ions
in the plasma. Another possibility to act on the plasma
is the injection of powerful beams of neutral particles
(typical energies in ITER ~1 MeV).
ITER will bring fusion physics into a new regime: The
alpha particles carry 20% of the generated fusion power,
which implies that at the highest ITER performance
(fusion power/input power = 10), the self-heating by the
alpha particles is twice the external input power. This has a
large effect on the way the plasma can be controlled. Only
localized heating methods, with a high power density,
like cyclotron heating can outweigh the alpha particle
heating, and can therefore be used for efficient plasma
control. Additionally, new effects can occur as the energetic
alpha particles can interact with instabilities, which
might lead to untolerable losses of fast particles. Many of
these effects can be studied already in present devices by
mimicking alpha particles by fast ions that are externally
injected, but the ultimate understanding of alpha-particle
physics needs to come from ITER.
c FIG. 1: Principle of
the tokamak. The hot
plasma is confined
by a superposition
of the toroidal
and the poloidal
magnetic fields. The
first is generated by
external magnetic
field coils, the second
by the electrical
current induced in
the plasma. Due
to the transformer
action to induce
the current in the
plasma, the tokamak
is a pulsed device by
definition (picture
EUROfusion).
22 EPN 47/5&6
fusion electricity
FEATURES
b FIG. 2: Dark coloured
countries are involved
in the EUROfusion
consortium (Sweden
and Finland are off
the map, but are
also member of
EUROfusion).
The bulk of the
EUROfusion research
is concentrated on
the various devices
indicated with
coloured dots. A
number of devices
in other countries
are used for specific
experiments (Picture
EUROfusion).
Achieving a high performance plasma is not the only
challenge. By far the largest quest for the fusion researchers
is to solve the heat exhaust problem. Namely, the
power generated in the core of the plasma needs to be
exhausted in a small part of the reaction chamber called
the divertor. In ITER, the neutrons, deposit a total of 400
MW more or less uniformly into the blanket structure
surrounding the vacuum chamber. But about 90% of the
remaining exhaust power of about 100 MW is convected
towards the divertor, leading to a steady state heat load
on the divertor components in ITER with peak values of
10-20 MW/m 2 . These are power densities that are close to
those at the surface of the Sun! The challenge of finding
a proper solution beyond ITER is largely going into two
directions: development of (new) plasma-facing materials
that are more robust against the plasma-wall interactions
as well as developing new magnetic geometries for the
divertor in which the peak heat load is distributed over
a larger surface. With respect to the latter direction: options
that are being studied in Europe are the snowflake
divertor in the Swiss TCV tokamak, the Super-X divertor
in the British MAST-Upgrade tokamak and liquid
materials divertors in a number of specific experiments.
Plasma regimes of operation (mission1) and Heat-exhaust
systems (mission 2) in the fusion roadmap are tightly interlinked.
This is illustrated by the following. Originally
most tokamaks in the world utilised carbon tiles as main
plasma-facing components and carbon-fibre composites
(CFC) in the divertor, as this material is very strong and
can withstand high temperatures up to about 1200°C.
Carbon is also a relatively light atom and does not pollute
the plasma too much when it enters (since the plasma is
quasi-neutral, each impurity ion with charge number Z
pushes out Z hydrogenic ions, leading to fuel dilution).
However, carbon has two important drawbacks: 1) it forms
dust, and 2) it binds with hydrogen. The effect of both is
that in a machine operating with 3 T (like ITER) after a
short time the whole tritium inventory is immobile due
to retention in the carbon dust and carbon plasma-facing
components. This implies opening and cleaning the
machine and subsequently separating the tritium from
the dust. It is for this reason that about 10-15 years ago
a deliberate choice has been made in Europe to switch
to full metal machines. The German ASDEX-Upgrade,
has gradually changed the wall material from full carbon
to full tungsten. JET has been modified in a single shutdown
from a carbon machine to a device with beryllium
walls and a tungsten divertor (exactly the same materials
as will be employed in ITER, see the following papers).
The Tore Supra superconducting tokamak in France is
presently being changed into WEST, a full tungsten device
able to run long plasma pulses. Tungsten has a high melting
point of 3422°C, but recrystallisation becomes important
above 1200°C. The result of a few years of operation of
ASDEX-Upgrade with a full tungsten wall and JET with
the ITER-like wall is that the hydrogen retention has been
reduced by a factor of ~15, which is sufficiently good for
ITER. However, it turned out to be much more challenging
to achieve a high plasma performance due to influx and
accumulation of tungsten in the plasma core, which – as
EPN 47/5&6 23
FEATURES
fusion electricity
c FIG. 3:
Schematic
drawings of the
Wendelstein
7-X stellarator,
showing the
complexity of the
device with the
magnetic field
coils, cooling
channels, vacuum
vessel and cryostat
(copyright Max-
Planck-Institut für
Plasmaphysik)
sketched above – leads to considerable fuel dilution. This
can be avoided by using special tricks as central plasma
heating (with radio frequency waves), surrounding the
plasma by a seeding gas and controlling instabilities at the
plasma edge to purge the tungsten out of the plasma. This
shows the rather intricate interplay between reaching a
high plasma performance and finding proper solutions for
the plasma heat exhaust geometry and material choices.
Apart from the integrated research of plasma-wall interaction
in tokamaks, new materials are constantly being
developed and tested in linear plasma devices, like MAG-
NUM-PSI and Pilot-PSI in The Netherlands and JULE-PSI
in Germany, in which the materials can be exposed to plasma
fluxes and fluences that are reminiscent to those in ITER.
The stellarator as back up strategy
Undoubtedly, the tokamak has the simplest design of the
relevant confinement devices. Because it also has the best
performance, international research has largely concentrated
on this line since the 1970’s. Besides its scientific
successes, the tokamak has a number of drawbacks. Firstly,
it is a pulsed device due to the fact that the plasma current
is induced by a transformer. Secondly, the tokamak
is prone to current-driven instabilities and disruptions
that necessitate active control tools for a stable operation,
as outlined above.
There is a second magnetic confinement device in
which the confining magnetic field is completely generated
by external field coils: the stellarator. The stellarator
is in principle net current free and, hence, the device is
intrinsically more stable. But every advantage comes with a
disadvantage: the design and construction of the stellarator
is much more complex (see Fig. 3), and this is the main
reason why it is generally lagging behind the tokamak.
Nevertheless, stellarator research has entered a new
era: On 10 December 2015, the super-conducting Wendelstein
7-X device with its optimised magnetic configuration,
located in Greifswald, Germany, and with a
diameter of 16 m (see Fig. 5) has been taken into operation.
Angela Merkel initiated on 3 February 2016 the
first hydrogen plasma, which had already an electron
temperature of 8 keV. Research in Wendelstein 7-X will
show the viability of this concept and its potential for a
future fusion power plant.
Concluding remarks
In this brief paper it has only been possible to describe
a small fraction of the European research in nuclear fusion,
and in doing that even only the tip of the iceberg
could be discussed. There are still many scientific and
technological challenges in fusion research, ranging from
a very fundamental nature to more applied issues. More
technical information is provided in the following papers
of this special issue. Apart from that it is a very interesting
and rewarding discipline to work in, it has the additional
prospect that it is contributing towards a solution to the
world energy and climate problem. n
About the Author
Tony Donné is Programme Manager of
the EUROfusion consortium, a position
he has held since June 2014. He obtained
his PhD degree (1985) at the Free University
of Amsterdam. Most of his scientific
career was devoted to research in the
field of high-temperature plasma diagnostics. From 2009
– 2014 he was heading the fusion research department
of the Dutch Institute for Fundamental Energy Research.
24 EPN 47/5&6
FEATURES
JET, THE LARGEST TOKAMAK
ON THE EVE OF DT OPERATION
llL.D. Horton 1,2 and the JET Contributors 3 – DOI: http://dx.doi.org/10.1051/epn/2016503
llEUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK
ll
1 JET Exploitation Unit, Culham Science Centre, Abingdon, OX14 3DB, UK
ll
2 European Commission, B-1049 Brussels, Belgium
ll
3 See the Appendix of F. Romanelli et al., Proceedings of the 25 th IAEA Fusion Energy Conference 2014, St. Petersburg, Russia
The Joint European Torus (JET) is the world’s largest operating tokamak and the
only such machine capable of operating with the fuel mixture (deuterium-tritium)
foreseen for a fusion reactor. Since it came into operation in 1983, JET has explored
fusion plasmas “in conditions and dimensions approaching those of a fusion reactor”
[1]. JET has demonstrated world-record levels of fusion power and energy production,
in conditions where the ratio of the fusion power generated to the input power to the
plasma, Q, approaches unity.
For the last decade, the JET has been executing a
Programme in Support of ITER, the next-step
device presently being built in the south of France
(see article by D. Campbell). The cornerstone of
this programme is the test of the interaction between fusion
plasmas and ITER-relevant plasma-facing components
(PFCs). To date, the majority of fusion experiments
have used carbon as the material in these components
because of carbon’s tolerance to overheating. Carbon machines
can test the boundaries of plasma performance in
the knowledge that overloading the PFCs will not lead to
changes in the component geometry. Carbon, on the other
hand, interacts chemically with the fusion fuel, leading to
a large fuel retention rate in the machine. This must be
avoided in a fusion reactor due to the need to breed tritium
in the process and on safety grounds. Indeed, both JET
and ITER have strict limits on the maximum amount of
tritium that can be trapped in the PFCs.
Carrying out JET’s programme has required upgrades
to the facility, in particular the installation of the same
combination of plasma-facing materials planned for
ITER (fig.1). In order to reach the highest fusion performance,
JET’s heating, diagnostic, protection and control
systems have also been enhanced. The programme’s
primary objective is presently to develop techniques in
deuterium plasmas of safely delivering the increased
heating power to JET whilst maximising the plasma energy
confinement and thus the equivalent fusion power
and whilst respecting the power and energy limits of the
new metallic PFCs.
Whilst the operating parameters of JET are the closest
to those foreseen for ITER, there remains a considerable
extrapolation between the two devices. The JET programme
thus incorporates a very strong element of theory
and model validation in order to provide a sound
basis for this extrapolation.
Once safe and reliable operation in deuterium has been
established, the last phase of JET’s present programme is
to test the dependence of this operation on the mass of
the fuel ions and to study and optimise deuterium-tritium
plasmas with large amounts of generated fusion power.
These experiments will provide a unique operational and
scientific knowledge base in preparation for ITER.
In addition to the plasma physics studies, a dedicated
DT technology programme is underway with projects in
the areas of neutron diagnostics and radiation damage,
neutronics and activation code validation, the tritium
cycle, and nuclear safety.
Performance with
the ITER wall material mix
Tungsten has ideal characteristics for the divertor targets,
which are subject to the highest heat and particle
fluxes: it has a high threshold for sputtering by plasma
particles, the highest melting point of any metal, and an
acceptably low affinity for hydrogen, implying a low rate
of fuel retention. While the first wall is typically subject
to much lower particle fluxes than the divertor, it is exposed
to higher energy particles escaping from the core
plasma. Since beryllium is a low-Z material, beryllium
atoms which penetrate the plasma after sputtering by
these high-energy particles will contribute much less to
plasma fuel dilution and plasma radiation than would
tungsten. Beryllium’s good thermal conductivity is also
EPN 47/5&6 25
FEATURES
Largest TOKAMAK on the eve
. FIG. 1: In any
fusion experiment,
managing the
interaction between
the hot plasma and
the surrounding
plasma-facing
surfaces is crucial. The
solution foreseen for
ITER, a combination
of beryllium in
the main vacuum
chamber near the hot
fusion plasma and
tungsten facing the
lower temperature
divertor plasma (at
the bottom of the
machine), is now
being tested at JET.
© CPS15.139-2C
advantageous in this application. Nevertheless, there is a
residual risk of localised melting of both beryllium and
tungsten under the high transient heat loads which can
occur during sudden plasma events such as ‘disruptions’.
Adequate mitigation measures must therefore be in place
to dissipate the plasma energy losses that can occur in
such cases, and this is a major focus of current fusion
plasma research.
The retention of hydrogen isotopes in JET has been
measured both before the installation of the new wall,
when JET’s plasma-facing components were predominantly
made of carbon, and with the new beryllium-tungsten
components. The expected reduction in
fuel retention of more than an order of magnitude has
been confirmed, a very positive result for ITER. More
importantly, the codes that describe the processes of wall
erosion, material migration and re-deposition have been
benchmarked on JET, also to the level of understanding
the spatial pattern of these processes inside the machine.
This has greatly increased confidence that the predictions
of fuel retention being made for ITER are accurate.
With the change in wall material, it has been necessary
to re-optimise the fusion plasmas in order to respect the
tighter power and energy limits on the metallic PFCs
and because of the potentially large impact of the new
materials on the plasma energy confinement. A good
example is the need to manage the source and transport
of tungsten from the divertor to the hot fusion plasma.
Accumulation of tungsten in the plasma core can lead
to strong radiative losses that more than compensate for
central heating and thus to hollow temperature profiles
(fig.2). Control of the tungsten transport by the use of
central heating can be used to avoid such accumulation
and recover the high temperature conditions.
Experiments with Tritium
Tritium affects the physics of fusion plasmas via its increased
mass and, when used in combination with deuterium,
via the production of high-energy alpha particles
from the D-T fusion reaction. The fuel mass influences
particle and energy transport due to the change in ion
gyro-radius and is important also for heating schemes
based on the ion cyclotron resonance (ICRH). Alpha particle
production is ultimately the scheme that will be used
in ITER to sustain the plasma temperature. Indeed, understanding
the additional dynamics generated by such
a self-sustained or burning plasmas is a key scientific
objective for ITER. In JET, the power deposited in the
plasma by fusion alphas will always be a small fraction
of the total heating power and thus the alpha particle
physics on JET focuses on single particle and threshold
effects related to fast particle – wave interactions.
Integration and Performance
Optimisation
Two routes are being explored to bring JET to maximum
fusion performance. The first relies on the fact that the
energy confinement of the plasma increases with plasma
current. By operating at the maximum possible plasma
current, it was possible in the first high power DT experiment
in 1997 to generate 4 MW of fusion power for the
duration of the high power heating phase.
Since the experiments in 1997, it has been realised that
operation at high plasma pressure can provide access to
higher confinement and thus higher fusion performance
for the same plasma current. This improvement with
plasma pressure is then limited by the plasma stability.
The second route to high fusion performance on JET
relies on achieving the maximum safe plasma pressure
at somewhat reduced plasma current.
Both routes to maximum fusion performance depend
on applying the full available heating power and therefore
on managing the exhaust of that level of power. Techniques
including stability control and mitigation, seeding
of extrinsic impurities to enhance edge radiation and
sweeping of the areas of maximum plasma load across
a wider region of the wall are being developed. The goal
is to achieve fusion power well above the 4 MW reached
in 1997. Obtaining standard confinement, as defined in
the scaling laws used to design ITER, at JET’s highest
current is predicted to lead to a fusion power of about 10
MW. Matching or even bettering this target is the goal of
the research into the high plasma pressure optimisation.
DT Technology Programme
The use of tritium and the production of large amounts of
14 MeV neutrons provide a unique opportunity to validate
codes, assumptions, models, procedures and data currently
used for ITER. An important example is the benchmarking
of neutronics codes for the calculation of neutron streaming
26 EPN 47/5&6
Largest TOKAMAK on the eve
FEATURES
through penetrations in the JET biological shield and for
subsequent evaluation of the gamma dose rates in remote
areas. Maps of the predicted neutron fluence generated by
the planned high power DT experiment are given in fig.3.
Measurements to validate these calculations are planned
using a combination of activation foils and thermo-luminescent
dosimeters. This validation will support the development
of maintenance activities on ITER.
Conclusion
The planned extensive use of tritium in JET supports an
important transition in the European fusion research programme
towards the realisation of a nuclear tokamak and
of fusion electricity on the grid [4]. It is an explicit strategic
goal of the European fusion programme (see article by T.
Donné) to train the scientists and engineers who will run
ITER and JET plays a key role in achieving that goal.
The JET experiments are logically divided in two; a
first Isotope Experiment in which plasma performance
will be compared for all three hydrogen isotopes (protium,
deuterium and tritium) and a subsequent Deuterium-Tritium
Experiment in which high fusion yields
will be produced and the physics associated with fusion
alpha particles will be studied. On the present schedule
the Isotope Experiment will take place in 2018-19 and the
DT Experiment in 2019-20. Together and based on previous
experimentation with JET’s ITER-like Wall, these
experiments allow optimisation of the ITER research
plan and, in particular, for the transition from protium
to deuterium to deuterium-tritium plasmas that will take
place as ITER moves from commissioning to nuclear
operation. n
Acknowledgement
This work has been carried out within the framework of
the EUROfusion Consortium and has received funding
from the Euratom research and training programme
2014-2018 under grant agreement No 633053. The views
and opinions expressed herein do not necessarily reflect
those of the European Commission.
About the Author
Lorne Horton is the JET Exploitation
Manager, responsible for the implementation
of the contract for the operation
of the JET facilities on behalf of the European
Commission and, in particular,
for ensuring that JET operation meets
the needs of the JET scientific programme defined by
the EUROfusion consortium of EU fusion laboratories.
References
[1] The JET Project (Design Proposal), Report of the Commission of
the European Communities, EUR 5516e, 1976.
[2] E. Lerche, M. Goniche, P. Jacquet, et al., Nucl. Fusion 56, 036022
(2016) (19pp).
[3] P. Batistoni, D. Campling, S. Conroy et al., Fusion Eng. Des. 109-
111, 278 (2016) .
[4] F. Romanelli, P. Barabaschi, D. Borba, et al., A roadmap to the
realisation of fusion energy, EFDA Report, ISBN 978-3-00-
040720-8 and https://www.euro-fusion.org/eurofusion/
the-road-to-fusion-electricity/
b FIG. 2: Accumulation
of tungsten in the
centre of the fusion
plasma can lead
to large radiative
losses (centre panel)
central peaking of
the plasma density
and even inverted
temperature profiles.
The addition of
central electron
heating, in this case
using ion cyclotron
resonance heating
(ICRH) can be used to
control the tungsten
transport in the
plasma, avoiding
the central radiation
(right panel) so
that the hot fusion
conditions are
recovered (from [2]).
b FIG. 3: Neutron
fluence maps for the
planned deuteriumtritium
experiment,
highlighting the
areas in which
neutron streaming
through penetrations
in the JET torus hall
will be measured.
Benchmarking these
calculations with
measurements will
increase confidence
in planning
maintenance
activities in ITER
(from [3]).
EPN 47/5&6 27
FEATURES
THE FIRST FUSION REACTOR: ITER
llD.J. Campbell – DOI: http://dx.doi.org/10.1051/epn/2016504
llon behalf of the ITER Organization, Domestic Agencies and ITER Collaborators
llITER Organization, Route de Vinon-sur-Verdon, CS90 046, 13067 St-Paul-lez-Durance Cedex, France
Established by the signature of the ITER Agreement in November 2006 and currently
under construction at St Paul-lez-Durance in southern France, the ITER project [1,2]
involves the European Union (including Switzerland), China, India, Japan,
the Russian Federation, South Korea and the United States. ITER (‘the way’ in Latin)
is a critical step in the development of fusion energy. Its role is to provide
an integrated demonstration of the physics and technology required for a fusion
power plant based on magnetic confinement.
In practical terms, the project’s goal is to construct and
operate a tokamak experiment which can confine a
deuterium-tritium plasma in which the α-particle
heating dominates all other forms of plasma heating.
Formally, the primary mission of the ITER project is to
demonstrate sustainment of a DT plasma producing
~500 MW of fusion power for durations of 300 - 500 s
with a ratio of fusion output power to input heating power,
Q, of at least 10. ITER is also designed to explore the
physics basis for continuous operation of fusion power
plants by investigating ‘steady-state’ plasma operation by
means of non-inductive current drive for periods of up
to several thousand seconds while maintaining a fusion
gain, Q, of ~5. If plasma confinement characteristics are
favourable, ITER would also be capable of exploring the
‘controlled ignition’ regime of tokamak operation (with
Q ~ 30) in which power plant plasmas are expected to
operate. The project’s technical goals encompass significant
technological demonstrations to prepare the design
basis for a fusion power plant.
The unique nature of the ITER international collaboration
is reflected in the scheme by which the components
for the tokamak and auxiliary plant are being
constructed. The ITER Organization (IO-CT) in France
is responsible for design integration, procurement of
components amounting to about 10% of the project’s
capital construction cost, management of the on-site
installation of the tokamak and plant, and, ultimately,
c FIG. 1:
Cutaway view
of the ITER
tokamak: the
cryostat is about
29 m in diameter
and 29 m high.
© 2016, ITER
Organization.
28 EPN 47/5&6
ITER
FEATURES
for the operation of the facility. The seven ITER partners
have each established Domestic Agencies (IO-DAs)
through which 90% of the facility’s components are being
procured ‘in-kind’ and supplied to the IO-CT for integration
into the ITER facility.
ITER Design, Manufacturing and
Construction
The engineering design for ITER has been developed
around a long-pulse tokamak with an elongated plasma
shape and a single-null poloidal divertor. The design has
been validated by wide-ranging physics and engineering
R&D: it is based on scientific understanding and extrapolations
derived from extensive experimental studies in tokamaks
in the international fusion research programme
spanning several decades (e.g. [3]) and on the technical
know-how flowing from the fusion technology R&D programmes
in the ITER Members (e.g. [4]). A schematic of
the ITER tokamak is shown in Fig. 1 and the principal
parameters are listed in Table 1.
TABLE 1. MAIN PARAMETERS OF THE ITER TOKAMAK
Plasma current (I p )
Toroidal field (at R = 6.2 m)
Major/ minor radius (R / a)
15 MA
5.3 T
6.2/ 2 m
Plasma elongation/ triangularity (κ / δ) 1.85/ 0.49
Installed auxiliary heating power
Fusion power (at Q = 10)
Pulse duration (at Q = 10)
73 MW
500 MW
~400 s
ITER is a superconducting device with several major
magnet systems [5]: the 18 toroidal field (TF) coils and 6
central solenoid (CS) modules are fabricated from Nb 3 Sn
superconductor due to the high fields required, e.g. 13 T
in the centre of the CS. The 6 poloidal field (PF) magnets
use NbTi superconductor, as do the 18 correction coils
(CC). The international collaboration formed around the
production of superconducting magnets for the ITER
tokamak has produced over 600 t of Nb 3 Sn (increasing
annual world production by approximately a factor of
10) and almost 250 t of NbTi superconducting strand.
Over 80% of the superconductors required for the ITER
magnets are now complete, and coil fabrication activities
are underway in 6 of the 7 partners’ factories (e.g., Fig.
2(a)). Series production of the high temperature superconducting
current leads will be launched during 2016.
Operation of the magnet systems, which are cooled by
supercritical helium, will be supported by the world’s
largest single-platform cryogenic plant.
Fabrication of the vacuum vessel, a double-walled
stainless-steel toroidal chamber with an outside diameter
of ~19.5 m and a height of ~11.5 m, is advancing,
with structures being produced under the responsibility
of four Domestic Agencies (e.g., Fig. 2(b)). The first
elements of the cryostat (~29 m diameter × ~29 m height
– the largest stainless-steel high vacuum pressure vessel
in existence when complete) have been delivered to the
ITER site. In-vessel components such as the stainless-steel
divertor cassettes (54 make up the entire divertor structure),
stainless-steel shielding blanket modules (440 cover
almost the entire first wall) and the associated (tungsten)
divertor and (beryllium) first wall plasma facing
components (PFCs) are undergoing prototyping and,
in the case of the PFCs, high heat flux testing to their
rated performance.
ITER will be equipped with a significant heating and
current drive (H&CD) capability. This will consist initially
of 33 MW of (negative ion based) neutral beam injection
using 1 MeV deuterium, 20 MW of electron cyclotron
resonance heating operating at 170 GHz, and 20 MW of
ion cyclotron radiofrequency heating operating in the
range 40-55 MHz. These systems are required for plasma
initiation, heating of the plasma to temperatures at which
fusion reactions can be initiated, controlling the fusion
burn, provision of a substantial fraction of the non-inductive
current drive for steady-state operation, control of the
plasma current profile to avoid magnetohydrodynamic
(MHD) instabilities and direct suppression of growing
plasma instabilities. An extensive diagnostic capability
consisting of about 50 large-scale systems will provide
plasma measurements for control, investment protection
and physics studies of burning plasmas, while a sophisticated
control, data acquisition and command system will
support all aspects of facility operation and protection.
On-site construction of the ITER facility is advancing
rapidly, as illustrated in Fig. 3.
Physics challenges for burning plasma
studies in ITER
Successful operation of ITER will open new frontiers
in fusion research involving the influence of a significant
α-particle population on plasma heating, transport
processes and stability. Moreover, to sustain high fusion
power, it will be critical to control the exhaust of power
and particles from the plasma to prevent overheating of
plasma facing surfaces.
ITER operation will evolve through several stages (e.g.
[6]): a period of hydrogen and helium operation will be
used to commission all tokamak and auxiliary systems;
this will be followed by a short period of deuterium operation
to approach thermonuclear conditions more closely
and to phase gradually into full DT operation, which will
then provide access to significant levels of fusion power
and α-particle heating.
Three ‘design basis’ scenarios have been assembled
from the physics basis developed by the international
fusion research community in recent decades. These
reference scenarios provided a conceptual basis for the
ITER design and form idealized targets for the various
EPN 47/5&6 29
FEATURES
ITER
c FIG. 2: (a) The first
complete TF coil
winding pack in
the manufacturer’s
factory, fabricated
from Nb 3 Sn
superconductor, with
overall dimensions of
13.8 m × 8.7 m.
© F4E, 2016;
(b) An outer
equatorial segment
(40˚ toroidal, inner
shell) of the ITER
stainless-steel
vacuum vessel with
3 port plug stubs
under manufacture.
© ITER Korea, 2016.
(b)
(a)
modes of plasma operation which will be explored in
ITER. Their basic parameters are summarized in Table 2.
The inductive scenario is expected to provide the simplest
route towards the achievement of high fusion power and
to allow the first studies of substantial α-particle heating.
The ‘hybrid’ scenario provides a relatively simple basis for
technology testing under long-pulse stationary conditions.
Fully non-inductive operation is an altogether more
complex plasma regime in which the total plasma current
is driven by a combination of auxiliary heating systems
and internal processes (bootstrap current). While the
basic principles of operation in this regime have been
understood for the past 20 years, and experimental
demonstrations of candidate modes of operation have
been made for periods of several seconds, considerable
research is required, both in existing devices and, eventually,
in ITER, to establish an operational mode in which
all requirements of plasma confinement and stability
are satisfied.
Like JET and all relevant fusion devices, ITER will
also be equipped with a divertor, located in the lower
region of the vacuum vessel. The material and geometry
of the divertor surfaces are designed to handle high heat
fluxes while allowing extraction of helium ‘ash’ produced
by DT fusion reactions. The operational functions of the
divertor are well-established in existing experiments, but
the critical step that ITER will make is to integrate this
power-handling strategy with a burning plasma core in
such a way that the core and edge plasmas perform as
intended, in benign coexistence.
Table 2. Key parameters of ITER reference scenarios
Inductive Hybrid Non-inductive
Plasma current (MA) 15 13.8 9
Energy confinement time, τ E (s) 3.4 1 2.7 1 3.1 2
Fusion power (MW) 500 400 360
Q 10 5.4 6
Burn duration (s) 300 – 500 >1000 ~3000
1
scaled from present experiments, 2 required to achieve Q ≥ 5
(b)
A key aspect of this solution to the power and particle
exhaust challenge is the choice of plasma facing materials.
Two metals, beryllium and tungsten, have been chosen,
with the former lining the first wall of the main plasma
chamber and the latter covering the divertor surfaces.
This material combination has been tested on JET in the
frame of the ITER-like wall (see article by L. Horton).
Fusion Technology at ITER
The development and testing of key ‘fusion’ technologies
required for construction of a fusion power plant is a
principal mission goal of the ITER project. A significant
element of this research is the Test Blanket Module (TBM)
Programme [7], which will involve the construction and
testing, by exposure to ITER plasmas, of 6 different concepts
of tritium breeding module. The breeding of tritium,
by reactions between neutrons emitted from the plasma
and lithium contained in either ceramics or (Li-Pb) eutectics
within blanket modules lining the reactor wall, is
fundamental to the fuel cycle in a fusion power plant burning
deuterium and tritium. While ITER can be fuelled by
tritium from external sources in the fission programme, it
is designed to conduct the first tests of concepts for tritium
breeding which could be applied in a DEMO reactor.
The primary research goal will be to confirm the rate
at which tritium can be produced: in DEMO, the ‘tritium
breeding ratio’, defined as the ratio at which tritium is
bred against the tritium burn rate, must certainly exceed
unity. ITER tests will allow the first studies of the tritium
production and extraction rates which can be achieved
in a practical design.
Once ITER makes the transition to routine DT operation,
the fusion power level, burn duration and duty cycle
required will necessitate real-time reprocessing of the tokamak
exhaust gas stream to provide DT fuel at an adequate
rate to sustain the planned experimental programme.
While a significant quantity of tritium can be stored on the
ITER site, this inventory will be recycled, resulting in as
much as 25 times this amount of tritium being reprocessed
annually to maintain the ITER experimental programme at
the required performance level. This will require a tritium
30 EPN 47/5&6
ITER
FEATURES
processing plant of unprecedented scale, and its operation
will establish the technical basis for tritium reprocessing
in fusion power plants.
The development and application of remote handling
technology for ITER will also provide a substantial basis
for the future application of this technology in the fusion
environment. Soon after the transition to DT operation,
activation of the ITER tokamak due to the interaction of 14
MeV neutrons with the reactor structure will require that
all maintenance, repair and upgrade work in the tokamak
core be carried out using remote handling methods.
A final significant facet of the ITER nuclear R&D programme,
and a key ITER mission, will be the demonstration
of the environmental and safety advantages of fusion
energy. After the submission of the formal application
documents and an extensive interaction between the
ITER Organization and the French nuclear regulatory
authorities, the French Government granted the Decree
of Authorization of a nuclear facility to the ITER Organization
in November 2012. ITER is now established
as Basic Nuclear Installation 174 (INB-174) within the
French regulatory framework.
Towards ITER Operation
Construction of the ITER facility is now moving forward
rapidly and the ITER partners have recently agreed to work
together towards a First Plasma date of December 2025.
DT operation is expected to begin about 10 years later. The
research programme under development will establish
the major lines of research within the ITER experimental
plan in order to optimize the fusion performance of the
device and to exploit the opportunities which ITER offers
for studies in burning plasma research at the reactor scale. n
Acknowledgments
This report represents the work of the staff of the ITER
Organization, the Domestic Agencies and many collaborators
in the Members’ fusion communities. The views
and opinions expressed herein do not necessarily reflect
those of the ITER Organization.
About the Author
David Campbell spent 14 years at JET,
Europe’s major fusion experiment,
followed by 10 years leading the EU’s
physics and plasma engineering R&D
activities for ITER. He joined the ITER
Organization in 2007 and is currently
Director of the Science and Operations Department,
which is responsible for developing the ITER facility’s
central control systems, for conducting the project’s fusion
physics research and for preparing the framework
for ITER operations.
References
[1] ITER Technical Basis, ITER EDA Documentation Series No. 24,
IAEA, Vienna (2002).
[2] O. Motojima, Nucl. Fusion 55, 104023 (2015).
[3] Progress in the ITER Physics Basis, ITPA Topical Groups et al.,
Nucl. Fusion 47, S1 (2007).
[4] ITER Technology R&D, ITER Joint Central Team and Home
Teams, Fusion Eng. Des. 55, 97 (2001).
[5] N. Mitchell et al., IEEE Trans. App. Supercond. 22(3) (2012).
[6] D.J. Campbell et al., paper ITR/P1-18, Proc. 24 th IAEA Fusion
Energy Conf., San Diego, (2012).
[7] L.M. Giancarli et al., Fusion Eng. Des. 109–111, 1491 (2016).
b FIG. 3:
Aerial view of the
ITER site showing
the current status of
facility construction.
The Tokamak Pit,
defined by the
cylindrical bioshield
(inner diameter
~30 m) visible in
the centre of the
Tokamak Complex,
hosts the ITER
tokamak shown
in Fig. 1.
© E. Riche / ITER
Organization,
July 2016.
EPN 47/5&6 31
FEATURES
FUSION AS A FUTURE
ENERGY SOURCE
llD.J. Ward – CCFE, Culham Science Centre, Abingdon, OX14 3DB, UK. – DOI: http://dx.doi.org/10.1051/epn/2016505
Fusion remains the main source of energy generation in the Universe and is
indirectly the origin of nearly all terrestrial energy (including fossil fuels) but it is
the only fundamental energy source not used directly on Earth. Here we look at the
characteristics of Earth-based fusion power, how it might contribute to future energy
supply and what that tells us about the future direction of the R&D programme.
The focus here is Magnetic Confinement Fusion although many of the points apply
equally to inertial confinement fusion.
c FIG. 1:
Calculated temperatures
in ITER
components in the
event of a full loss of
cooling water, taken
from [6] (the curve
marked VV illustrates
the temperature at
the Vacuum Vessel).
Fusion Characteristics
as an Energy Source
Resources
The potential energy resource from fusion is enormous,
primarily because the energy produced per unit mass
of fuel is so large, and this is the principal reason why
fusion R&D has been pursued. If we were able to harness
energy simply from the fusion of two deuterium atoms
(D-D fusion), which is possible in theory but difficult in
practise, we could supply mankind’s energy needs for
billions of years. At present, however, we have a much
less ambitious target, the fusion of deuterium with tritium
(D-T fusion), which is roughly 100 times higher in
cross-section. As tritium decays with a half-life of 12.3
years, it is not abundant on Earth so the plan is for a
fusion power plant to be self-sufficient in tritium, using
the neutrons which result from the fusion reaction to
convert lithium into tritium. With present estimated fuel
reserves of lithium, there is enough to provide mankind’s
energy needs for thousands of years, by which time we
may have solved the problem of D-D fusion.
Designing a fusion plant to be self-sufficient in tritium is
not a trivial problem. Although simply surrounding a fusion
neutron source with natural lithium can, in theory, produce
up to 70% more tritium than required, the practical reality
is more difficult [1]. There needs to be a box structure to
contain the lithium compound, there needs to be coolant
flowing to take away the large amounts of energy deposited
by the neutrons and we want to restrict the thickness of the
structure to minimise the size of the containing magnets.
In existing designs, changing the isotopic mix of the lithium
and including a neutron multiplier such as beryllium or lead
are used as tools to produce an optimised design, but this is
far from complete and demonstrated. Tests of these fusion
blankets are proposed for the ITER device.
One aspect of tritium supply will relate to the growth
phase of fusion power. To start up a new power plant, an
initial inventory of tritium is required and this will have
to come either from another fusion plant or from a fission
plant. Particularly in the early implementation phase, it is important
to minimise the inventory of tritium needed to start
up a new plant whilst ensuring sufficient tritium is available.
Waste
One of the differentiating factors of fusion when compared
to fission is the waste products. Unlike fission, fusion reactions
do not produce radioactive waste directly but the
neutrons can cause radioactivity in the surrounding materials
– hence the emphasis on developing and testing of low
activation materials, those that do not generate long-lived
radioactive waste [2]. The same happens in fission plants
of course but there the structural activation is a very small
part of the waste produced – in fusion it is the dominant
part. One goal of the fusion R&D programme is to optimise
the use of materials, for instance to minimise the need for
repository storage, perhaps to zero, but this is not guaranteed.
Optimising material properties is a key, and somewhat
neglected area, and would be substantially advanced by a
major materials test programme, including a source of fusion
relevant, 14 MeV neutrons, such as the proposed IFMIF [3],
as this is not an area of particular focus for ITER.
32 EPN 47/5&6
Fusion as a Future Energy Source
FEATURES
b FIG. 2: Example
of an exploration
of how future
electricity demand
may be met, in a
future of reduced
carbon emissions.
Taken from [8].
Emissions
Apart from the large potential resource the main benefit of
fusion as foreseen is the lack of carbon emissions. Because
it does not rely on combustion of fuels, fusion is intrinsically
a low carbon energy source and the atmospheric
emissions of other pollutants such as particulates, NO x etc
are also low. Evaluating the externalities of different energy
sources, including fusion, leads to the conclusion that
combustion-based technologies generally have the highest
externalities and that the external costs of fusion are low,
primarily because of low atmospheric emissions [4,5].
Safety
One aspect of fusion plant design that is considered more
important than others, when optimising design, is safety.
Because of the low energy available to drive an accident
and the low hazard to be released in the event of an accident,
fusion plants are proposed as passively safe, that is
they should not cause substantial damage even if all active
safety systems fail (for instance see Fig. 1). In generic studies,
the objective has been to design a plant in which no
design-basis accident requires the evacuation of the local
population. In working with specific devices in specific
locations this has to be refined to the local conditions,
for instance a lot of work has been done on the safety of
ITER [6]. As with tritium production, this is an active
area of research for future power plants, informed by the
ongoing work for the design and construction of ITER.
Costs
An area of substantial uncertainty relates to future costs
of fusion power plants. Given the incomplete information
for designing a power plant it is difficult to be precise
about costs, although the main cost items are already
known, particularly buildings, magnets and conventional
equipment. In the conceptual designs that have been investigated
in the past targets such as generating electricity
at less than 0.1€/kWh have been used as a guide [4]. There
are two particular uncertainties presently: information
emerging from ITER is providing extra information on
the costs of fusion, and the assumptions about plant availability
in spite of needing to regularly change components
in a power plant are known to be challenging. At the
same time the future costs of other energy systems are
also very uncertain so it is difficult to be conclusive in
cost assessments – nonetheless, cost should be a strong
influencing factor in design optimisation. Again, ITER
is providing key information in this area.
Fusion in the Future Energy Market
In discussing fusion’s role in a future energy market there
are a number of key questions:
••
How large will future demand for energy, particularly
low carbon energy, be?
••
Will fusion be available, when and at what cost relative
to other low carbon sources?
••
How will public acceptance of different energy technologies
evolve and will that increase or reduce fusion’s
potential role?
The course appears to be set for emerging economies
to become significant users of energy, substantially larger
than present demand in developed economies; at present
the pressure for this to come from low carbon sources is
strong and increasing. This presents a future of dramatically
increasing challenge; meeting carbon emissions
targets in 2030 for instance does little to contribute to
meeting targets foreseen for 2070, by which time global
energy demand may have doubled again but allowable
emissions fallen by another factor of 4.
EPN 47/5&6 33
FEATURES
Fusion as a Future Energy Source
The route to fusion power was originally addressed in
the 1970’s, at which point the work needed to achieve fusion
as an energy source was mapped out and the cost of doing
that work estimated. In present money that would exceed
$50B [7]. JET has used about 2% of the resources that were
identified as necessary at that time; ITER is likely to take us
around 30-40% of the remaining way. The additional work
is focussed on materials and technology testing leading to
the construction of a demonstration (DEMO) device.
In costs, superconducting magnets are very expensive
today but costs will fall. Fusion has strong economies of
scale so larger plants are expected to be more cost competitive.
The comparators for fusion may be advanced fission,
solar with energy storage and coal with (improved)
Carbon Capture and Storage, but such comparisons cannot
be made reliably today. Given that developing a new
energy source, fusion, as a low carbon energy option can
be done with a tiny fraction of the resources needed to
transform global energy systems to low carbon (at less
than 0.1% of investment in other energy systems over
the same period) it would be imprudent to stop that development
on the basis of cost alone.
The influence of future public opinion is difficult to predict.
In some world regions the present view of risks from radiation
is very distorted when compared to other, much larger, risks to
human health such as air pollution or transport accidents, and
if this continues, in some world regions at least, then advanced
nuclear fission plants may be disfavoured and fusion more
likely to play a role. This is something that must continue to be
an important consideration in the fusion R&D programme,
influencing the work to optimise a fusion plant in terms of
cost, safety, emissions and waste.
An evolving energy system
We have seen how the different properties of fusion make
for a complex optimisation when designing a power plant
and how the present programme, particularly ITER, contributes
to exploring this. This same complexity extends
to designing an optimised energy supply system and the
role that fusion can play within it.
There is a big question around the speed with which an
energy system can be changed. If a new energy technology
became available in 2050, for instance, how long would it be
before it could be a major player on the future energy scene
[8,9]? A limit to the growth rate of a new technology may be
as high as 25% per year or as low as 10% and this could have
a significant impact on the introduction of fusion. Assuming
that a target of 1TW installed power is needed for a significant
contribution to future energy supply, then the initial scale of
introduction and the growth rate determine how quickly this
could be achieved. If 20 countries each introduced a 1GW
plant in 2050 (and there were enough tritium to start them
up) then a growth to 1TW would take between 17 and 40
years, depending on the growth rate. Although this is not a
major issue today, it is an example of how consideration of the
“market pull” can feedback to plant requirements, design and
hence the R&D programme. Figure 2 shows an example of
attempts to look at future energy scenarios, including fusion,
particularly as fusion goes through a growth phase.
Impact on the R&D Programme
Producing an optimised working fusion power station is
the goal of the European fusion R&D programme. Optimisation
includes designing for cost, availability, safety,
emissions, waste, growth rate etc. and is a non-trivial
problem, not least because the different areas can pull in
different directions and because the energy systems in
which fusion will be embedded differ around the world.
As the R&D moves away from physics towards technology,
these new areas become increasingly important and
a new skill set is required; fusion is moving out of the
laboratory and the expertise contained within the R&D
programme must develop accordingly. n
About the Author
David Ward has worked in fusion since
the first JET plasma and had strong
involvement in the first JET deuterium-tritium
experiments, in which
more than 1MW of controlled fusion
power was first produced on Earth, and
the later experiments in which up to 16 MW of fusion
power was produced. After many years of working on
both theory and experiment, David took on the role of
leading the JET work carried out to help in the design of
the ITER. From there the transition to technical work and
a management role in systems studies for power plants,
in particular DEMO, was a natural step.
The work in integrated design of a conceptual power
plant includes determining the expected properties of fusion
as a power source with a natural link to other energy systems
and the likely role of fusion in a future energy market. This
has involved collaborations with other energy researchers,
outside fusion and also led to David’s selection as the EU-
ROfusion Project Leader for fusion Socio-Economic studies.
References
[1] L. El Guebaly et al, Fus. Eng. Des. 84, 2072 (2009).
[2] S. J. Zinkle, Fus. Eng. Des. 74, 31 (2005).
[3] J. Knaster et al., Nuc. Mats. Energy, Online May 2016.
[4] D. Maisonnier. et al, Nuclear Fusion 47, 1524 (2007).
[5] D.J. Ward, Fus. Eng. Des. 82, 528 (2007).
[6] N. Taylor et al, Fus. Eng. Des. 87, 476 (2012).
[7] US Energy Research and Development Administration Report
(1976) ERDA-76/110 (later published in Dean, J. Fusion Energy
17, 263 (1998) )
[8] H. Cabal et al., submitted to Energy Strategy Reviews.
[9] K. Vaillancourt et al., Energy Policy 36, 2296 (2008).
34 EPN 47/5&6
FEATURES
A NEWCOMER: THE WENDELSTEIN
7-X STELLARATOR
llThomas Klinger – DOI: http://dx.doi.org/10.1051/epn/2016506
llMax-Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17489 Greifswald, Germany
Stellarators (“star generators”) belong to the earliest concepts for magnetic
confinement of fusion plasmas. In May 1951, a confidential report authored by Lyman
Spitzer at the Princeton Plasma Physics Laboratory (PPPL) was issued, in which he
proposed the “figure eight” stellarator based on the idea to generate the required
rotational transform of magnetic field lines by twisting the torus into a figure-8.
The first experimental device based on this idea started operation in early 1953.
In the 1950’s a series of stellarator experiments were built, most of them at PPPL.
This development has led to the large “Model-C”
stellarator, operated at PPPL from 1961-1969
until it was converted into the “Symmetric Tokamak”
in 1970, after breakthrough results
reported from Russian tokamaks in 1968. The first “Wendelstein”
stellarator, the “1-A” went into operation in 1960
at the Max-Planck Institute for Physics and Astrophysics.
It was followed by a series of uninterrupted developments
until now, when the large, superconducting stellarator
“Wendelstein 7-X” (in short W7-X) went into operation.
In that sense, stellarators are not “newcomers”, but the
trust in the concept has undergone a number of ups and
downs and W7-X intends to make a major contribution
to bring stellarators to maturity.
Stellarators and optimisation
The fundamental idea of stellarators is to generate rotational
transform – the twist of the magnetic field - to
a major extend by external coils [1]. This is different
from the tokamak concept, where the poloidal component
of the magnetic field is generated by a strong
current running in the plasma (see article by T. Donné).
This difference has major consequences: The stellarator
magnetic field is very much “frozen-in” by the external
coils, whereas the tokamak field is strongly defined by
the particular plasma scenario with the associated radial
current distribution. Furthermore, a current-carrying
plasma tends to be less stable than a current-less
plasma and steady-state operation is more difficult in a
tokamak because of the need for efficient non-inductive
current drive. There is a lot of freedom in the choice
of external coils for generating a stellarator magnetic
field. Consequently, there is a whole “family” of coil
configurations [2] with the main lines being (a) stellarators,
(b) heliotrons/torsatrons, (c) heliacs (see Fig. 1).
Indicated are also the experimental devices, smaller
ones for addressing more basic plasma physics questions
and bigger ones with direct relevance for reactor extrapolation.
The classical stellarator combines planar coils
to generate a toroidal magnetic field and sets of helical
coils with counter-directed currents to create rotational
transform. Torsatrons and heliotrons use helical coils
with co-directed currents to produce a twisted toroidal
magnetic field. A vertical magnetic field is generated as
well and must be compensated with additional vertical
field coils. In contrast to stellarators and heliotrons/torsatrons,
the magnetic axis in a heliac follows a helical
path to form a toroidal helix with twisted magnetic field
lines. The vertical positions of the planar toroidal field
coils follow the helical path and a central conductor
further enhances the twisting of the toroidal magnetic
field. Again, vertical magnetic field coils are required
for compensation.
.FIG. 1: Overview
diagram of
helical magnetic
confinement concepts
and the associated
devices. The
stellarator line has
split up into different
branches after the
concept of modular
coils was introduced.
EPN 47/5&6 35
FEATURES
The Wendelstein 7-X Stellarator
c FIG. 2:
View into the torus
hall during assembly.
Tools for stiffening
and handling have a
yellow colour. Clearly
seen on the left is the
(last) magnet module
that is inserted
into the torus.
A different approach is based on modular three-dimensionally
shaped magnetic field coils. These coils allow
shaping the magnetic field within a wider range, based
on specific physics criteria. This iterative process is called
“optimization” and the magnetic field of the modular
stellarator Wendelstein 7-X was shaped to satisfy the
following criteria [3]:
1. nested magnetic flux surfaces with sufficiently small
magnetic islands
2. good plasma equilibrium at high average beta � 4% 1
3. good magnetohydrodynamic stability at average beta
� 4%
4. small neoclassical transport in the relevant collisionless
regime
5. minimized bootstrap current in the relevant collisionless
regime
6. improved confinement of fast particles
7. feasible modular magnetic field coils
The predecessor device of Wendelstein 7-X, the Wendelstein
7-AS, was only partially optimized and is denoted
as “advanced” in comparison to classical stellarators.
Wendelstein 7-AS has already shown improved plasma
properties due to physics-based shaping of the magnetic
field. Another sub-group are the quasisymmetric stellarators,
i.e., non-axisymmetric configurations in which
the magnetic field strength depends only on one angular
coordinate within the magnetic flux surfaces. Quasisymmetric
stellarators meet optimization criteria as well but
not necessarily the same as above. The three types of
quasi-symmetry are: quasi-helical, quasi-poloidal, and
quasi-axisymmetric. It should be emphasized that optimization
of the magnetic field is a promising path to
bring stellarators to maturity, i.e., to allow for integrated
high-performance plasma scenarios that are comparable
to those of tokamaks of the same plasma volume.
The construction
of Wendelstein 7-X in brief
The project Wendelstein 7-X was officially started in 1996.
The initial phase of the project was dominated by design,
specification and tendering of the major components of
the device, i.e. about 60 km length of niobium-titanium
superconductor, the 80 m³ volume and 33 t heavy plasma
vessel, the 525 m³ volume and 170 t heavy outer vessel,
the 254 ports, the 72 t heavy central support ring, and the
manufacturing of the 20 planar and 50 non-planar superconducting
coils. At the same time, the development of
10 gyrotrons with 140 GHz frequency and 1 MW output
power for 30 min duration was started. The assembly of
the device started in 2004 and was completed 10 years later,
with more than one million assembly hours spent. The
assembly work was challenging because of (a) three-dimensional
geometry and high precision requirements,
(b) difficult access situations especially in the cryostat
and for the in-vessel components, and (c) the extremely
crowded space situation in the torus hall. This leads
to unusually high work density and strong sensitivity
against perturbations in the work flow. Intense project
management on the daily level was required, based on
strict industry-proven rules and well defined processes,
in particular systematic quality management, change
management, and risk management.
1
<β> is the average ratio of plasma pressure to external magnetic
field pressure
36 EPN 47/5&6
The Wendelstein 7-X Stellarator
FEATURES
The assembly can be described in 17 major assembly
steps (roughly in sequence): (1) Assembly of the thermal
insulation on a half-module of the plasma vessel, (2) threatening
of five non-planar and two planar superconducting
coils over the plasma vessel half-module, (3) bolting the
coils to a segment of the central support ring, (4) welding
of the additional inter-coil support elements, (5) joining
two pre-assembled magnet half-modules to a module, (6)
installation of the superconducting bus bars and the joints
to interconnect the coils, (7) installation and welding of the
helium distribution pipework, (8) assembly of the thermal
insulation on the inner side of the outer vessel module, (9)
insertation of the magnet module into the lower half-shell,
(10) installation of the vertical supports and cryo feet, (11)
welding of the outer vessel upper half-shell on the lower-half
shell, (12) assembly of the thermal insulation on the
ports, (13) installation of the 254 ports and their welding
on the plasma vessel and the outer vessel, (14) joining the
5 modules by bolting the central ring modules, welding the
vessels and connecting the pipes and bus bars, (15) assembly
of the 14 current leads, (16) assembly of the in-vessel
components, (17) assembly of the device periphery. Fig. 2
shows a view into the torus hall during the installation of
the last of the five pre-assembled magnet modules.
The island divertor concept
For the development of the stellarator reactor line, it is of
utmost importance to qualify a viable divertor concept. Different
from a tokamak, the divertor in a stellarator cannot
be toroidally symmetric. One approach is a divertor with
helical shape as installed in the heliotron “Large Helical Device”
in Japan. For the Wendelstein 7-X optimized stellarator
a different solution was found, the island divertor (Fig. 3).
The magnetic field of Wendelstein 7-X is five-fold periodic
with a strong variation of the cross-section from triangular
to bean-shape and exhibits natural magnetic islands at the
edge where the rotational transform has a resonance 2 close
2
At a resonance the twisting magnetic field line closes upon itself.
to unity. On each magnetic field period, one pair of island
divertor modules is installed where the cross-section of the
magnetic field is predominately bean shaped. The natural
magnetic islands intersect the target and partially baffle
plates. In this way, a well-defined flow of particles from the
plasma edge (outside the confinement volume) to the wall
is ensured and the interaction between the plasma and the
wall is decoupled from the core plasma region. The target
plates of the island divertor have to withstand a heat flux
of up to 10 MW/m 2 , which is close to the technical limits,
especially under steady-state conditions. Wendelstein 7-X
follows a staged approach with inertially cooled limiters in
the first stage of operation, an inertially cooled divertor in
the second stage, and a water-cooled divertor in the third
stage. In addition to the divertor and the baffles, the remaining
wall surfaces are covered either with water-cooled steel
panels (surface area 62 m 2 ) or with water-cooled graphite
heat shields (surface area 47 m 2 ). The steady-state operation
requirements of Wendelstein 7-X imply that there is no
uncooled plasma facing component allowed, which means
considerable efforts in design, engineering and assembly.
First results
from Wendelstein 7-X operation
The assembly of Wendelstein 7-X was officially completed
on 20 th of May 2014. The commissioning process
of the device consisted of six major steps, i.e., (1)
pump-down of the cryostat volume to high-vacuum
conditions, (2) cool-down of the magnet system to 3.4 K,
(3) test of all normal-conducting control and trim coils,
(4) pump-down of the plasma vessel to ultrahigh-vacuum
conditions, (5) ramp-up of the superconducting
magnet system to achieve 2.5 T magnetic induction on
axis, (6) preparation for plasma operation, in particular
plasma vessel baking, wall conditioning, test of gas inlets
and device control. After commissioning step (5), the
magnetic field geometry was confirmed with an electron-beam
mapping technique. Wendelstein 7-X has
started operation on the 10 th of December 2015 with
b FIG. 3:
Schematic drawing of
the island
divertor (left
diagram). Ten
modules (five top
and five bottom)
are placed at the
toroidal position with
bean-shaped cross
section. The target
plates of the divertor,
indicated by red bars,
intersect the natural
magnetic islands
located at the edge
(right diagram). The
blue bars indicate
the baffle plates.
EPN 47/5&6 37
FEATURES
The Wendelstein 7-X Stellarator
. FIG. 4:
Overview over the
plasma parameters
achieved during
the first operation
campaign of
Wendelstein 7-X.
The doubling of the
injected ECRH energy
from 2 MJ to 4 MJ
has considerably
improved the plasma
performance.
helium as filling gas (Fig. 4). The maximum injected
electron cyclotron resonance heating (ECRH) energy
was limited to 2 MJ to protect the five inboard limiters
from thermal overload. After wall conditioning with repetitive
low-power ECRH pulses, the impurity level has
dropped to acceptable values and the plasma parameters
as well as the pulse duration have significantly improved.
The maximum available ECRH power was 4.3 MW.
On the 3 rd of February 2016 the operation with
hydrogen as filling gas had started. The heat loads on
the limiters allowed to double the maximum injected
ECRH energy up to 4 MJ. This has improved the plasma
performance considerably and both higher-power
1 s duration and lower-power 6 s duration discharges
could be operated routinely. During the 10 weeks of
operation about 1000 experiments could be conducted
with the about 30 diagnostic systems in operation. The
first operation stage of Wendelstein 7-X has exceeded
all expectations with regard to reliability and availability
of the device, plasma performance parameters, and
validity of the obtained data. Already a large variety of
physics programs could be conducted, including the
investigation of the central electron root [6], plasma
rotation, influence of external trim coils on wall loads,
and first impurity transport studies. The analysis of the
data is in progress and valuable experience for the next
operation stage has been gained. Also the formation of
the scientific and the operation team was successful, in
particular the international cooperation in the framework
of the EUROfusion consortium (see article by T.
Donné) and a strong cooperation with U.S. American
research laboratories and universities.
The path to steady-state operation
of fusion relevant plasmas
Steady state operation of plasmas with fusion-relevant parameters
is one of the grand challenges in fusion research. The
fusion triple product n∙T∙τ E usually deteriorates for longer
plasma discharges, either due to lack of long-pulse heating
and current drive performance or heat load limits of plasma
facing components. The stellarator concept without net
plasma current is inherently steady-state. However, a large
number of measures must be taken to make a fusion device
– including stellarators – steady-state capable: (a) The magnet
system must be superconducting. (b) A steady-state heating
system must be developed for the operation of the experimental
devices. Here ECRH is a most promising path, since
the gyrotron development has made enormous progress
during the past 10 years. The 1 MW 140 GHz gyrotrons for
Wendelstein 7-X have proven 30 min of operation without
any loss of performance. Using water-cooled mirrors and
diamond windows, the ECRH beam can be quasi-optically
directed into the plasma. (c) All plasma-facing components
must be actively (water) cooled. (d) Plasma diagnostic systems
must be prepared to cope with steady-state conditions.
(e) The requirements on control and data acquisition of a
steady-state fusion device are much higher than for any
short-pulse machine. The sheer amount of data, the necessity
of highly-available systems, and continuous control of
the plasma make dedicated developments indispensable. In
summary, a steady-state device with fusion-relevant plasma
parameters is not only a physics program (predominately aspects
of plasma-wall interaction) but requires also a dedicated
engineering and development program and Wendelstein 7-X
will make a serious contribution.
Reactor concepts for stellarators
- the way forward
Wendelstein 7-X is clearly the key device for the qualification
of optimized modular stellarators as possible
candidates for a fusion power plant. A burning-plasma
power plant study based on stellarator optimization using
non-planar coils is the HELIAS 5-B (helical-axis advanced
stellarator) with the following design parameters
[4]: plasma volume 1400 m -3 , number of non-planar coils
50, major radius 22 m, overall diameter 60 m, average
magnetic induction on axis 5.9 T, magnetic energy 160 GJ.
To go directly from Wendelstein 7-X to such a device
would be too large a step and an intermediate device
is most likely needed to study the physics of a burning
stellarator plasma and to develop the related technologies,
in particular blanket modules that match the stellarator
geometry and the associated remote handling technologies.
Prior to that step, Wendelstein 7-X has to fulfill its
missions to demonstrate: (1) constructability, (2) plasma
performance, (3) divertor operation, (4) steady-state
operation. The forthcoming two operation phases, that
extend until mid 2025, will be decisive for making major
progress towards achievement of these milestones. n
References
[1] A.H. Boozer, Physics of Plasmas 5(5), 1647 (1998)
[2] M. Wakatani, Stellarator and Heliotron Devices, Oxford University
Press (1989)
[3] J. Nührenberg and R. Zille, Phys. Lett. A 129, 113 (1988)
[4] F. Warmer et al. Plasma Physics and Controlled Fusion 58,
074006 (2016)
38 EPN 47/5&6
FEATURES
LOW TEMPERATURE PLASMA
APPLICATIONS IN MEDICINE
llK.-D. Weltmann 1 , H.-R. Metelmann 2 , Th. von Woedtke 1 – DOI: http://dx.doi.org/10.1051/epn/2016507
ll
1 Leibniz Institute for Plasma Science and Technology (INP Greifswald), Greifswald, Germany
ll
2 Greifswald University Medicine, Greifswald, Germany
The main field of plasma medicine is the direct application of cold atmospheric plasma
(CAP) on or in the human body for therapeutic purposes. CAP is effective both to
inactivate a broad spectrum of microorganisms including multiple drug resistant ones
and to stimulate proliferation of mammalian cells. Clinical application has started in the
field of wound healing and treatment of infective skin diseases.
Cold atmospheric plasma (CAP)
sources for medical application
A well-established field of atmospheric plasma application
is electro surgery where thermal plasma effects are
used above all for coagulation and tissue cutting. In contrast,
plasma medicine is focused actually on low temperature
plasmas (< 40°C) to avoid thermal effects on living
structures. Cold atmospheric plasma (CAP) sources for
medical application have to meet particular requirements.
Such devices have to guarantee manageable, stable, reliable,
and reproducible operation at low temperature and
open atmospheres. Besides a comprehensive characterization
of qualitative and quantitative plasma parameters
and “macroscopic” characteristics especially a meaningful
knowledge of biological performance is an essential prerequisite
for both effective and safe medical application.
During recent years, mainly three basic types of CAP
devices were tested and partially applied for medical purposes
(Fig. 1) [1,2,3].
In the volume dielectric barrier discharge (DBD) plasma
is ignited in the gap between an isolated high voltage
electrode and the target to be treated, i.e. in medical application
human tissue (e.g. skin or wound surface) is part
of the discharge electrode configuration. In the surface
DBD, plasma is ignited around an individually designed
electrode structure (e.g. circular or grid-like) which is
isolated from a counter electrode. Both electrodes can
serve either as high voltage or ground electrodes. For
treatment of living tissue, the plasma has to be brought in
close vicinity of the target to be treated. With both DBD
configurations, atmospheric air is usually the working gas.
In a plasma jet device, the electrode setup for plasma
generation is located usually in a capillary or tube-like
arrangement in most cases inside a pen-like device. Diverse
electrode configurations can be used, e.g. pin electrodes,
ring electrodes, plate electrodes etc. A working gas
is flowing through the tube. The plasma is ignited inside
the device. The effluent is blown out along the gas flow
and can be brought into direct contact with the target
to be treated. Several plasma jet devices are using noble
gases like helium or argon, but air or gas mixtures are
also useful as working gases.
Independent on the basic principle of plasma generation,
all these atmospheric pressure plasmas are small
scale and filamentary and are generated inside small
discharge gaps (p*d-scaling of breakdown voltage). The
plasmas are non-uniform and constricted and consist
of micro discharges or filaments, i.e. these are transient,
short lived plasmas.
Biologically active plasma components
and basic mechanisms of action
In general, cold atmospheric pressure plasma is a mixture
of reactive components including charged species (ions
and electrons), excited neutral species mainly from the
working gas, reactive oxygen and nitrogen species, visible,
ultraviolet (UV) and infrared (IR) radiation and other
electromagnetic fields (Fig. 2). Dependent on the individual
configuration of the plasma source, composition,
relationship and quantity of these plasma compounds
may vary significantly.
Based on a huge number of basic research using cultivated
microorganisms and human cells [3], two main
basic principles of biological plasma action have been
identified recently:
1. Biological plasma effects are significantly caused by
plasma induced changes of the liquid environment
of cells.
2. Reactive oxygen and nitrogen species (ROS, RNS) generated
in or transferred into liquid phases by plasma
treatment play a dominating role in biological plasma
activity.
EPN 47/5&6 39
FEATURES
Low TEMPERATURE plasma applications in medicine
According to the actual knowledge, UV part of CAP
has low or no direct biological effects because typically
low doses are emitted by plasma devices designated for
medical use. However, its supporting role in reactive species
generation by photochemical activity has to be taken
into consideration.
Electrical fields or current, respectively, reaching living
tissue is strongly dependent on type of discharge and
therefore might have varying direct biological effects. In
this field, much more research is needed to finally enlighten
the role of this plasma compound for its direct part
in biological and medically relevant plasma action but
also for its role in the generation or support of action of
other plasma compounds, above all of reactive species [4].
However, the dominating role of ROS and RNS is established
and demonstrated by several experimental setups
independent on the specific plasma device used [5,6]. Generation
of ROS and RNS is mainly referable to atmospheric
oxygen and nitrogen which are part of the working gas in
air-based plasma sources but is also admixed into the plasma
in the case of noble gas-based plasma sources if they
are working at open atmospheric conditions. According
to the actual state of knowledge, differences of biological
performance between plasma sources are mainly referred
to quantities of ROS and RNS or its proportion of mixture
in the respective plasma. However, possible role of UV
radiation or electric fields has to be kept in mind.
The fundamental insight of the dominating role of
ROS and RNS was highly valuable because the large and
well established field of redox biology now can serve as a
sound scientific basis to explain biological effects of CAP.
ROS and RNS regularly occur in cell biological processes
(e.g. superoxide O 2- •, hydrogen peroxide H 2 O 2 , hydroxyl
radical •OH, singlet oxygen 1 O 2 , nitric oxide •NO, nitrogen
dioxide •NO 2 und peroxynitrite ONOO - ). Therefore,
mammalian cells have protective mechanisms to
save from reactive species concentrations going beyond
physiological levels. Such so-called oxidative stress might
have severe consequences, e.g. genotoxic DNA changes.
However, detailed investigations using well-established
experimental procedures could demonstrate repeatedly
that detrimental plasma effects on cells in general and
particularly on DNA result either in cellular repair processes
or in induction of programmed cell death (apoptosis)
as a direct consequence. It has been demonstrated
that application of cold atmospheric plasma does not
cause increased risk for genotoxic effects [7,8].
Three general biological plasma effects have been
described repeatedly that are most relevant for medical
application [3]:
••
its potential to inactivate a broad spectrum of microorganisms
including multidrug resistant ones
••
its potential to stimulate cell proliferation and consequently
to promote tissue regeneration
m FIG. 1: Basic
principles of cold
atmospheric
plasma (CAP)
for biomedical
research and
medical application
40 EPN 47/5&6
Low TEMPERATURE plasma applications in medicine
FEATURES
••
its ability to inactivate mammalian cells and especially
cancer cells by initialization of the programmed cell
death (apoptosis)
Medical application of CAP
Since 2013, first CAP sources got CE certification as medical
devices. One of it is the argon-driven cold atmospheric
plasma jet kINPen MED (neoplas tools GmbH,
Greifswald, Germany), which is based on comprehensive
physical, biological, pre-clinical and clinical characterization
[9,10]. Two other well-investigated medical CAP
devices are the jet-like microwave-driven Ar-plasma
torch MicroPlasSter (ADTEC, Hunslow, UK) and the
PlasmaDerm device (CINOGY GmbH Duderstadt, Germany)
which is based on a volume DBD working with
atmospheric air [11].
These plasma sources are certified mainly for the treatment
of chronic wounds as well as pathogen-based skin
diseases. The integrated concept of plasma-supported
wound healing combines antimicrobial (antiseptic) plasma
activity with a direct stimulation of tissue regeneration
(Fig. 2). With these devices, routine application in
medical practice in first clinics and doctor’s offices above
all in Germany has started. In the treatment of long-lasting
chronic and infected wounds promising results are
reported particularly in cases where conventional treatment
fails. According to the feedback of the doctors that
use it, a re-start or acceleration of wound healing process
up to complete wound closure is reported in more than
80 % of the patients as a preliminary result. Additionally,
clinical users emphasize the CAP effectivity to eradicate
multiple drug resistant bacteria (e.g. MRSA).
A highly topical field of basic and preclinical research
is CAP application in cancer therapy due to the fact that
CAP can inactivate cancer cells by induction of the
programmed cell death (apoptosis). Because these cells
seem to be much more sensitive for CAP treatment compared
to non-malignant cells it opens up new options of
supportive CAP application e.g. in surgical or radiative
cancer eradication as well as in palliative cancer therapies
[12,13,14].
Possibilities of plasma application in dentistry include
disinfection of tooth root canal, treatment of dental implants
both for biofilm removal and improvement of bone
cell adherence and therapy of intraoral infections and
also wounds [15].
Besides these large fields of basic, pre-clinical and clinical
research in plasma medicine, further fields of medical
plasma use, such as ophthalmology, cardiology, pneumology
or plastic and aesthetic surgery are investigated.
Actual challenges and further
prospects
Despite the fact that first clinical application of CAP devices
have already been realized, there are several needs
to further improve and optimize this innovative plasma
technology in medicine. There are both physical and
technological but also biological and medical challenges.
Two main points have to be addressed in the next future:
••
adaptation of plasma devices for specific medical applications
with regard to manageability under ergonomic
and application site-related aspects;
••
adaptation of plasma with regard to its composition to
realize specific and selective biological effects.
m FIG. 2: With cold
atmospheric plasma
(CAP) a mixture of
reactive components
dominated by
reactive oxygen and
nitrogen species
(ROS, RNS) is working
on living tissue, e.g.
a wound. Wound
healing by plasma
is a combination
of inactivation
of bacteria and
stimulation of tissue
regeneration.
EPN 47/5&6 41
FEATURES
Low TEMPERATURE plasma applications in medicine
For application-adapted plasma devices, several physical
and technical concepts are existing for flat DBD-based
plasma devices and plasma jet arrangements for large-area
treatment, catheter-like plasma devices for endoscopic
application as well as plasma devices to reach difficult
to access areas in cavities e.g. for dental applications
[2,16,17].
For the adaptation of plasma composition to specific
biological effects and subsequently to specific and selective
medical applications, much more interdisciplinary
research about detailed mechanisms of biological plasma
effects and the specific role of the different plasma
components, above all of the reactive species is needed.
Furthermore, it is not known in detail how and in which
extent the individual state of health of the patient influences
the success of plasma therapy, which has to be taken
into account to define individual treatment parameters.
Finally, perhaps the greatest challenge for the next
future is to find or define a specific parameter or set of
parameters for a device-independent control and monitoring
of plasma treatment similar to the common “dose”
in mainly irradiation-based physical therapies like laserand
radiotherapy.
“The main field of plasma medicine is the direct application
of cold atmospheric plasma (CAP) on or in the human body
for therapeutic purposes. CAP is effective both to inactivate
a broad spectrum of microorganisms including multiple drug
resistant ones and to stimulate proliferation of mammalian
cells. Clinical application has started in the field of wound
healing and treatment of infective skin diseases.
”
Unique advantages of plasma application for therapeutic
purposes are:
1. Active components are generated locally and only for
the required duration of the application on-site primarily
by a physical process.
2. Biologically active plasma components (above all reactive
oxygen and nitrogen species) are the same as occur
in regular physiological and biochemical processes in
the body but cannot be supported adequately by drugs.
3. Because of its localized and short-term generation by
local plasma treatment these substances can be detoxified
by processes of regular cell metabolism, i.e. there
is no increased risk of plasma application.
It can be expected that plasma medicine will become
an independent and successful part of modern medicine
within the next years. To attain this objective, more systematic
clinical trials are essential to meet the demands
of evidence based medicine. n
Acknowledgement
The authors gratefully acknowledge the substantial financial
support provided by the German Federal Ministry
of Education and Research, the Ministry of Education,
Science and Culture and the Ministry of Economics, Construction
and Tourism of the State of Mecklenburg-Western
Pomerania (Germany) as well as the European Union,
European Social Fund.
About the authors
Klaus-Dieter Weltmann and Thomas
von Woedtke are from Leibniz Institute
for Plasma Science and Technology
(INP), Greifswald, Germany.
Klaus-Dieter Weltmann is Chairman
of the Bord of INP and Head of the
Research Division Plasmas for Environment
and Health. He held a Professorship
for Experimental Physics at
Greifswald University and a Visiting
Professorship at New York University.
Thomas von Woedtke is Program
Manager Plasma Medicine at INP
and Professor for Plasma Medicine
at Greifswald University Medicine.
Hans-Robert Metelmann (M.D.,
D.M.D., Ph.D.) is Professor and Head
of Department of Oral and Maxillofacial
Surgery/Plastic Surgery at Greifswald University
Medicine, Greifswald, Germany.
References
[1] K.-D. Weltmann et al., Pure Appl. Chem. 82, 1223 (2010)
[2] G.Y. Park et al., Plasma Sources Sci Technol 21, 043001 (2012)
[3] Th. von Woedtke et al., Phys. Rep. 530, 291 (2013)
[4] T. Darny et al., 2015 IEEE International Conference on Plasma
Sciences (ICOPS); DOI: 10.1109/PLASMA.2015.7179640
[5] D.B. Graves, J. Phys. D: Appl. Phys. 45, 263001 (2012)
[6] D.B. Graves, Clin. Plasma Med. 2, 38 (2014)
[7] K. Wende et al., Cell Biol. Int. 38, 412 (2014)
[8] K. Wende et al., Mutat. Res. Genet. Toxicol. Environ. Mutagen.
798, 48 (2016)
[9] K.-D. Weltmann et al., Contrib. Plasma Phys. 49, 631 (2009)
[10] S. Bekeschus et al., Clin. Plasma Med. 4, 19 (2016)
[11] G. Isbary et al., Expert Rev. Med. Devices 10, 367 (2013)
[12] A.M. Hirst et al., Tumor Biol. 27, 7021 (2016)
[13] M. Keidar, Plasma Sources Sci. Technol. 24, 033001 (2015)
[14] M. Schuster et al., J. Cranio Maxill. Surg. (2016); DOI: 10.1016/j.
jcms.2016.07.001
[15] S. Cha and Y.-S. Park, Clin. Plasma Med. 2, 4 (2014)
[16] K.-D. Weltmann et al., Contrib. Plasma Phys. 54, 104 (2012)
[17] K.-D. Weltmann et al., IEEE Trans. Plasma Sci. 40, 2963 (2012)
42 EPN 47/5&6
Iwant to draw your attention on
the WTC failure issue.
As Structural Engineer, specialized
with Eladio Dieste in
Stability of Structures, the explanation
of the article on WTC is absurd. I have
worked by twenty years in Intelligent
Structures stability, and one structure
was nominated for fib 2010 Outstanding
Structure Awards.
I have studied the WTC failure by two
stability investigation methods: 1) energy
flow minimisation and 2) monitoring displacements
vs. efforts convergence.
The structure of the WTC was held
by the bracing of the exterior columns
by the floor steel joist at each floor level.
The weakest point is the union column-steel
joist, and although it was fully
protected with fire-resistant foam, it is a
[Letter to the Editors]
Dear Editors,
union without redundancy. Redundancy
of joints is a must for live loads.
Structural stability is a subject beyond
the mechanical strength; a temperature of
800 ° F (measured indirectly by the colour
of steel), which does not affect the strength
of steel, caused differential deflections that
were enough to disconnect the junctions
steel joist- pillar. The joints, which were
welded for construction speed, were not
redundant and failed. When the joints
failed, the steel joists fell and the pillars
buckled for lack of horizontal bracing.
The fire affected the floors above of
the impact floor, just the failing of only
two connections trigger a displacement
mechanism, floor by floor, exactly as seen
in the videos.
A study by two researchers at MIT,
Prof. Oral Buyukozturk and Dr. Oguz
Gunes, by other roads leads to the same
result as listed above (see The Collapse of
Twin Towers: Causes and Effects, Keynote
Lecture, EFCA 2004 CONFERENCE,
May 22-May 25, 2004 Istanbul, Turkey).
Without these failings the towers would
not have fallen. They recommend increasing
the redundancy of connections
onwards. This failure mechanism is consistent
with the final NIST report 2008
in http://ws680.nist.gov/publication/
get_pdf.cfm?pub_id=861610
Modern high-rise structures use other
structural systems, including e.g. high
performance concrete.
The structural engineering requires
faithful adherence to the laws of physics,
and good engineering judgement. People’s
lives depend on us. n
José Zorrilla - Uruguay
Thoughts from a Former NIST Employee
Iwas a member of the NIST technical
staff during the period 1997-
2011. I initially joined the High
Performance Systems and Services
Division and later became a member of
what was, at the time, the Mathematical
and Computational Sciences Division of
the Information Technology Laboratory.
My fellow NIST employees were among
the finest and most intelligent people
with whom I have ever worked.
I did not contribute to the NIST WTC
investigation or reports. But in August of
this year, I began to read some of those
reports. As I then watched several documentaries
challenging the findings of
the NIST investigation, I quickly became
furious. First, I was furious with myself.
How could I have worked at NIST all
those years and not have noticed this
before? Second, I was furious with NIST.
The NIST I knew was intellectually open,
non-defensive, and willing to consider
competing explanations.
The more I investigated, the more apparent
it became that NIST had reached
a predetermined conclusion by ignoring,
dismissing, and denying the evidence.
Among the most egregious examples is
the explanation for the collapse of WTC 7
as an elaborate sequence of unlikely events
culminating in the almost symmetrical total
collapse of a steel-frame building into
its own footprint at free-fall acceleration.
I could list all the reasons why the
NIST WTC reports don't add up, but
others have already done so in extensive
detail and there is little that I could add.
What I can do, however, is share some
thoughts based on common sense and
experience from my fourteen years
at NIST.
First, if NIST truly believes in the veracity
of its WTC investigation, then it
should openly share all evidence, data,
models, computations, and other relevant
information unless specific and
compelling reasons are otherwise provided.
For example, would the release
of all files and calculations associated
with the ANSYS collapse initiation model
jeopardize public safety to an extent
that outweighs the competing need
for accountability?
Second, in its reports, NIST makes a
great show of details leading to collapse
initiation and then stops short just when
it becomes interesting. The remainder of
the explanation is a perfunctory statement
that total collapse is inevitable and obvious.
It is easy to see through this tactic as avoidance
of inconvenient evidence. In response
to any challenges, NIST has provided curt
explanations from its Public Affairs Office.
There were many contributors to the
NIST WTC investigation: Why not let them
openly answer questions in their own voice
with the depth of knowledge and level of
detail that follows from the nuts and bolts
of their research?
Lastly, awareness is growing of the disconnect
between the NIST WTC reports
and logical reasoning. The level of interest
in "15 years later" is a good example.
Due to the nature of communication in
today's world, that awareness may increase
approximately exponentially. Why
not NIST blow the whistle on itself now
while there is still time?
Truth is where our healing lies. n
Peter Michael Ketcham, USA
EPN 47/5&6 43
[Letter to the Editors]
The Editors respond
It is the policy of EPN to publish by invitation. Prospective
authors are suggested by members of our
Editorial Advisory Board, who cover various disciplines
and come from different countries.
This particular Feature article 'On the physics of highrise
buildings collapses', related to the attack on the WTC,
followed the same route. We expected this topic to be of
wide interest to our readers and thus invited the suggested
authors to submit their manuscript. EPN does
not have a formal review/rejection policy for invited
contributions.
In the present case we realized that the final manuscript
contained some speculations and had a rather controversial
conclusion. Therefore a 'Note from the editors' was added,
stressing that the content is the sole responsibility of the authors
and does not represent an official position of EPN.
Since some controversy remains, even among more competent
people in the field, we considered that the correct
scientific way to settle this debate was to publish the manuscript
and possibly trigger an open discussion leading to an
undisputable truth based on solid arguments. Therefore we
asked NIST, as principal investigator of the WTC collapse, to
send us a reaction to the article. Their response can be found
elsewhere on these pages.
It is shocking that the published article is being used
to support conspiracy theories related to the attacks on
the WTC buildings. The Editors of EPN do not endorse
or support these views.
In future, prospective authors will be asked to provide an
abstract of the proposed article, as well as an indication of
other related publications to allow the editors to better assess
the content of the invited articles. n
NIST position on the WTC investigation
T
he NIST WTC investigation
team members feel
that since our study of the
World Trade Center building
(WTC 1, 2 and 7) collapses ended in
2008, there has been no new evidence
presented that would change our findings
and conclusions, and therefore,
nothing new that we can contribute to
the discussion.
NIST firmly stands behind its investigation
results, and that the body of
evidence still overwhelmingly leads to
the following scenarios:
• The WTC Towers collapsed because
aircraft impact damage and debris
dislodged fireproofing from critical
steel components, jet fuel-initiated
fires burned very hot for long duration
when fed by debris and office
materials, and the heat eventually
weakened the exposed steel until it
lost integrity and led to a global failure;
and
• WTC 7 collapsed because damage
caused by debris from the falling WTC
1 ignited fires on multiple floors, the
heat expanded and dislodged a beam
connecting a key perimeter column to
both a long-span central beam and a
critical internal support column, and
the column’s failure set off a chain reaction
of failures across the building’s
steel infrastructure.
Our comprehensive website, http://
wtc.nist.gov, covers all aspects of the
WTC investigation and provides three
sets of “frequently asked questions”
(on the overall investigation, the WTC
towers and WTC 7) that address—
based solely on our findings—many
of the claims made by those holding
alternative views as to how the three
WTC buildings collapsed.
The NIST investigation into the collapses
of WTC Buildings 1, 2 and 7 was
the most detailed examination of structural
failure ever conducted. Based on
the recommendations from this investigation,
two sets of major and far-reaching
building and fire code changes have
been adopted by the International Code
Council (ICC) into the ICC’s I-Codes
(specifically the International Building
Code, or IBC, and the International Fire
Code, or IFC). The 40 code changes
were adopted less than five years from
the release of the final report on WTC 1
and 2, and less than two years following
the release of the final report on WTC
7. This is an extraordinarily rapid pace
in the code making and approval process—a
solid affirmation by the ICC
that the work done by the NIST WTC
investigation team was of the highest
quality and critical to ensuring that
future buildings—especially tall structures—will
be increasingly resistant to
fire, more easily evacuated in emergencies,
more accessible to first responders
when needed, and most importantly,
safer overall.
Thank you for your interest in the
NIST WTC investigation. n
Michael E. Newman,
Senior Communications Officer,
Public Affairs Office
National Institute
of Standards and Technology
100 Bureau Drive, Stop 1070
Gaithersburg, MD 20899-1070
44 EPN 47/5&6
OPINION
Opinion: Die Energiewende
Adelbert Goede is adviser of the Dutch Institute for Fundamental
Energy Research, member of the Kopernikus Science Advisory
Board and Fellow of the European Physical Society.
Around 2012, Germany embarked
on an ambitious
Renewable Energy programme
aimed at phasing out fossil
and nuclear power and replacing it by
renewable energy, the so-called Energiewende
or Energy Transition. Its
long-term goal is to generate at least
80% of its electricity from renewables
by 2050. To date the counter has hit
30% renewable electricity with about
45 GW installed wind farm capacity,
a remarkable feat only surpassed by
China and the USA. In solar power it
ranks second to China only.
The share of renewables in Germany,
now at around 30%, is an average.
On a sunny and windy day, like May
8 th , this may go up to 90%. On the other
hand, on a calm and cloudy day like
October 25 th , fossil coal, lignite and gas
fired power plants are scrambled to
cover demand. This not only makes
stability control of the electricity grid
ever more challenging, it also increases
carbon dioxide emissions, its reduction
being one of the main objectives
of the Energiewende. From the outset,
these objectives were a clean, affordable
and reliable energy supply. As it
happens none of these objectives are
currently met.
To bring about the Energiewende,
the main instrument is subsidies. Investors
are guaranteed a fixed high
price for 20 years for their renewable
electricity and this electricity has priority
over other generators fed into
the grid. Total cost exceeds B€ 20/yr,
to be paid by customers through their
electricity bill. As a consequence, electricity
prices in Germany are one of
the highest in Europe. A reform is
now being drafted based on auctions,
similar to the US. Being a step in the
right direction, this is not the ideal
solution either, as optimal energy use
is not achieved by setting market prices
on generating capacity, but requires
a system approach where generation,
transmission and distribution to end
users are consistently managed.
A system approach not only considers
the energy source but also
includes energy storage. To develop
energy storage, basic research needs
to be stepped up. It requires a consistent
long-term approach leading from
basic research to pilot and demonstration.
Recently, Germany did just
that through the BMBF Kopernikus
programme. Research Institutes and
Industry collaborate in a ten year project
called Power to X (P2X), aimed
at converting intermittent supply of
electricity into other forms of energy,
like gaseous or liquid fuel or chemicals.
These fuels are made from water
and air (CO 2 and N 2 ) by splitting the
molecules and recycling the CO 2 after
use by recapturing it from the air. Fuels
may then be stored in conventional
way in large quantities for extended
periods of time at high energy density
to cover the mismatch between supply
and demand characteristic of intermittent
renewables. It couples the electricity
grid to the existing gas network
and to the oil infrastructure as well as
powering the chemical industry.
After completion of the Kopernikus
Programme, the Energiewende
may well look different, its initial
troubles likely dismissed as teething
troubles. A ground swell of public
opinion now steers energy policy
Do not focus
on the energy
source alone,
take a system
view and
include the
waste recycling,
storage
and public
acceptance
in your
thinking
away from fossil and nuclear power
into renewables. If P2X is successful,
duly integrated in 10 years’ time, renewables
will look cheap as prices of
wind farms and solar panels continue
to tumble, whilst the cost of decommissioning,
waste disposal and climate
change will have to be factored into the
cost of nuclear and fossil power. For
now, the message seems clear; do not
focus on the energy source alone, take
a system view and include the waste
recycling, storage and public acceptance
in your thinking. n
COMING EPS EVENTS
••
The 6 th International Topical
Meeting on Nanophotonics
and Metamaterials
- NANOMETA
04 » 07 january 2017
Seefeld - Tirol, Austria
www.nanometa.org
••
1 st Biology for Physics
Conference: Is there new
Physics in Living Matter?
15 » 18 january 2017
Barcelona, Spain
www.bioforphys.org
••
Breakdown of ergodicity
in quantum systems: from
solids to synthetic matter
06 » 07 february 2017
London, UK
https://royalsociety.org/
science-events-andlectures/2017/02/ergodicityin-quantum-systems/
• • MORE ON:
www.eps.org
EPN 47/5&6 45
ANNUAL INDEX
ANNUAL INDEX VOLUME 47 - 2016
AUTHOR INDEX
»»
A
Angot T. See Le Lay G.
Asplund M. See José J.
»»
B
Balogh A. Summer School Alpbach 2015:
A pilgrimage to Erwin Schrödinger’s grave •
47/1 • p.08
Bagnoli F. Everyday physics: delicious
ice cream, why does salt thaw ice? • 47/2 •
p.26 | Everyday physics: we shoot a bullet
vertically. Where will it land? • 47/4 • p.27
Beijerinck H. Opinion: an oral history •
47/2 • p.31
Bender C.M. PT symmetry in quantum
physics • 47/2 • p.17
Benedek G. EPL for the IYL 2015 • 47/2 • p.21
Brogueira P. See Trindade A.C.
»»
C
Campbell D.J.
The first fusion reactor: ITER
• 47/5&6 • p.28
Charbonel C. See José J.
Cherchneff I. See José J.
Clanet C. See Cohen C.
Cohen C. Physics of ball sports • 47/3 • p.13
»»
D
Diehl R. See José J.
Di Virgilio A. First direct detection of
gravitational waves • 47/2 • p.09
Donné T. Challenges on the road towards
fusion electricity • 47/5&6 • p.20
Dudley J. See Rivero González J.
»»
E
Emmerich R.
Historic sites: former Institute
of Physics,Würzburg University • 47/5&6 • p.04
»»
F
Falkner A. See Balogh A.
Ferrero M. Letter to the editors: the world
is better than it has ever been • 47/3 • p.31
Fleck B. 20 Years of SOHO • 47/4 • p.27
Forterre Y. Physics of rapid movements in
plants • 47/1 • p.27
Fraxedas J. ECOSS 31 (Barcelona 2015) •
47/1 • p.07
»»
G
Godinho M.H. See Trindade A.C.
Goede A. Letter: the need for Basic Energy
Research • 47/2 • p.25 | CO 2 -Neutral Fuels •
47/3 • p.22 | Die Energiewende • 47/5&6 • p.46
Giuntini L. See Macková A.
»»
H
Hermans L.J.F. (Jo) Physics in daily life:
disappearing iron • 47/3 • p.26
Hertel I. Obituary: Wolfgang Sandner
(1949-2015) • 47/1 • p.11
Hidalgo C. Opinion: Globalization,
Development and Inequality • 47/1 • p.31
Horton L.D. JET, The Largest Tokamak on
the eve of DT Operation • 47/5&6 • p.25
Huber M.C.E. Opinion: announcing breakthroughs
and "Science Etiquette"
• 47/4 • p.30
»»
I
Imboden D.M.
Opinion: excellent universities:
how do we foster them? • 47/3 • p.32
»»
J
Jones S. 15 years later: on the physics of
high-rise building collapses• 47/4 • p.21
José J. On the origin of the cosmic elements and
the nuclear history of the universe • 47/4 • p.15
»»
K
Ketcham P.M. Letter: thoughts from a
Former NIST Employee • 47/5&6 • p.44
Klein T. Physics in daily life: confessions of a
deuteranope • 47/5&6 • p.16
Klinger T. A newcomer: the Wendelstein
7-X Stellarator • 47/5&6 • p.35
Korn A. See José J.
Korol R. See Jones S.
Kundt W. Letter to the editors• 47/3 • p.21
»»
L
Lee D. EPS Council 2016• 47/3 • p.06 |
Rüdiger Voss is the next EPS President-elect
• 47/5&6 • p.08
Le Lay G. Silicene: silicon conquers the 2D
world • 47/1 • p.17
López-Valverde M.A.
Project UPWARDS:
Rethinking Planet Mars in preparation for
ExoMars • 47/1 • p.10
»»
M
Macková A. Discovering new information
from historical artefacts • 47/3 • P.17
Marino A. See Salvador Balaguer E.
Marmottant P. See Forterre Y.
Metelmann H.-R. See Weltmann K.-D
Millington A. European Science TV and New
Media Festival and Awards 2015 • 47/1 • p.06
Mlynář J. Historic sites: Ernst Mach house •
47/2 • p.04
Müller D. See Fleck B.
»»
N
Newman M.E.
Letter: NIST position on the
WTC investigation 47/5&6 • p.44
Nienhuis B. Physics Nobel Prizes 2016:
topology in condensed matter physics •
47/5&6 • p.07
Noblin X. See Forterre Y.
»»
O
Ongena J.
• 47/1 • p.04
»»
P
Patrício P.
Historic sites: Hotel Metropole
See Trindade A.C.
Petit-Jean Genaz C.
2016 Asian Committee
for Future Accelerators (ACFA)/IPAC’16
Accelerator Prizes • 47/2 • p.08
»»
Q
Quilliet C. See Forterre Y.
»»
R
Rivero González J. Inspired by light:
close of the International Year of Light • 47/2
• p.06
Rossel C. Editorial: a new year in focus •
47/1 • p.03 | Editorial: EPS and Open Science
Policy • 47/3 • p.03 | Statement by C. Rossel,
President of the EPS, after UK's decision to
leave the EU • 47/4 • p.04 | News and views
from the former EPS presidents • 47/4 • p.05
| Science denial • 47/5&6 • p.03
Ruivo Martins D. See Simões C.
»»
S
Salomon E. See Le Lay G.
Salvador Balaguer E. Turning point
for Young Minds • 47/4 • p.07
van de Sanden R. See Goede A.
Schoutens K. See Nienhuis B.
Simões C. Historic sites: Cabinet of Physics,
University of Coimbra, Portugal • 47/3 • p.04
Šmit Ž. See Macková A.
Szamboti A. See Jones S.
»»
T
Tamayo A. See López-Valverde M.A.
Teixeira P.I.C. See Trindade A.C.
Thielemann F.-K. See José J.
Trindade A.C. Soft Janus, wrinkles and all •
47/1 • p.22
»»
V
Velasco V.R. Editorial: big challenges and
international collaboration • 47/2 • p.03 |
New EPN Science Editor • 47/5&6 • p.05
Verhoeven J. Letter: in defence of basic
research • 47/1 • p.21
»»
W
de Waele A.T.A.M. Fascinating optics in a
glass of water • 47/2 • p.28
Wagner F. Foreword on the special issue on
Nuclear Fusion and Plasma Physics • 47/5&6 • p.19
Walter T. See Jones S.
Ward D.J. Fusion as a Future Energy Source
• 47/5&6 • p.32
Watt G. See Benedek G.
Weltmann K.-D. Low temperature plasma
applications in medicine • 47/5&6 • p.39
von Woedtke Th. See Weltmann K.-D.
»»
Z
Zamfir N.-V. Large-Scale Research
Infrastructures: essential framework of
today’s physics research • 47/4 • p.03
Zorrilla J. Letter to the Editors • 47/5&6 • p.43
46 EPN 47/5&6
volume 47 - 2016
ANNUAL INDEX
»»
Annual index
Volume 47 - 2016 • 47/5&6 • p.46
»»
Editorials
A New Year in Focus Rossel C.
Big challenges and international
collaboration Velasco V.R.
EPS and Open Science Policy Rossel C.
Large-Scale Research Infrastructures:
essential framework of today’s physics
research Zamfir N.-V.
Science denial Rossel C.
»»
Event
European Science TV and New Media Festival
and Awards 2015 Millington A.
»»
Everyday physics
Delicious ice cream, why does salt
thaw ice? Bagnoli F.
We shoot a bullet vertically. Where will
it land? Bagnoli F.
»»
Historic sites
Cabinet of Physics, University
of Coimbra, Portugal Simões C. and
Ruivo Martins D.
Ernst Mach house, Ovocny trh 7, Prague,
Czech Republic Mlynář J.
Former Institute of Physics, Würzburg
University Emmerich R.
Hotel Metropole, Place de Brouckère 31,
Brussels, Belgium Ongena J.
»»
Highlights
47/1 • 12 summaries • p. 12-16
47/2 • 12 summaries • p. 11-16
47/3 • 10 summaries • p. 09-12
47/4 • 14 summaries • p. 08-14
47/5&6 • 15 summaries • p. 09-15
»»
Features
15 years later: on the physics of high-rise
building collapses Jones S., Korol R.,
Szamboti A. and Walter T.
20 Years of SOHO Fleck B. and Müller D.
A newcomer: the Wendelstein 7-X
Stellarator Klinger T.
Challenges on the road towards fusion
electricity Donné T.
CO 2 -Neutral Fuels Goede A. and
van de Sanden R.
Discovering new information from historical
artefacts Macková A., Šmit Ž. and
Giuntini L.
EPL for the IYL 2015 Benedek G. and
Watt G.
Fascinating optics in a glass of water
de Waele A.T.A.M.
Fusion as a Future Energy Source Ward D.J.
Foreword on the special issue on Nuclear
Fusion and Plasma Physics Wagner F.
JET, The Largest Tokamak on the eve of DT
Operation Horton L.D. and the JET
Contributors
Low temperature plasma applications in
medicine Weltmann K.-D., Metelmann
H.-R., von Woedtke Th.
On the origin of the cosmic elements and the
nuclear history of the universe José J.,
Asplund M., Charbonel C., Cherchneff I.,
Diehl R., Korn A. and Thielemann F.-K.
Physics of ball sports Cohen C. and
Clanet C.
Physics of rapid movements in
plants Forterre Y., Marmottant P.,
Quilliet C. and Noblin X.
PT symmetry in quantum physics
Bender C.M.
Silicene: silicon conquers the 2D world
Le Lay G., Salomon E. and Angot T.
Soft Janus, wrinkles and all Trindade A.C.,
Patrício P. , Teixeira P.I.C., Brogueira P. and
Godinho M.H.
The first fusion reactor: ITER Campbell D.J.
Letters to the editors
»»
Inside EPS
EPS Council 2016 Lee D.
EPS directory • 47/4 • p.31
New EPN Science Editor Velasco V.R.
News and views from the former EPS
presidents Rossel C.
Statement by C. Rossel, President of the EPS, after
UK's decision to leave the EU Rossel C.
Turning point for Young Minds
Salvador Balaguer E. and Marino A.
Rüdiger Voss is the next EPS Presidentelect
Lee D.
»»
Letter
MATTER INDEX
In defence of basic research Verhoeven J.
Letter to the Editors Kundt W.
Letter to the Editors Zorrilla J.
NIST Position on the WTC
investigation Newman M.E.
The need for Basic Energy Research Goede A.
The world is better than it has ever
been Ferrero M.
Thoughts from a Former NIST
Employee Ketcham P.M.
»»
Obituary
Wolfgang Sandner (1949-2015) Hertel I.
»»
Opinion
An oral history Beijerinck H.
Announcing breakthroughs and
"Science Etiquette" Huber M.C.E.
Die Energiewende Goede A.
Excellent universities: how do we
foster them? Imboden D.M.
Globalization, Development and
Inequality Hidalgo C.
»»
Physics in daily life
Confessions of a deuteranope Klein T.
Disappearing iron Hermans L.J.F. (Jo)
»»
Prizes - Awards - Medals
2016 Asian Committee for Future Accelerators
(ACFA)/IPAC’16 Accelerator Prizes
Petit-Jean Genaz C.
2016 Lise Meitner Prize MacGregor D.
The EPS Edison Volta Prize 2016 awarded to
Michel Orrit • 47/5&6 • p.06
Physics Nobel Prizes 2016: topology in
condensed matter physics Nienhuis B.
and Schoutens K.
»»
Report
ECOSS 31 (Barcelona 2015) Fraxedas J.
Inspired by light: close of the International
Year of Light Rivero González J. and
Dudley J.
Project UPWARDS: Rethinking Planet
Mars in preparation for ExoMars
López-Valverde M.A.
Summer School Alpbach 2015: A pilgrimage
to Erwin Schrödinger’s grave Balogh A.
New DPG president • 47/3 • p.05
»»
Research
First direct detection of gravitational
waves Di Virgilio A.
Wendelstein 7-X fusion device
produces its first hydrogen plasmay
• 47/2 • p.07
EPN 47/5&6 47
