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Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Department of Energy.
Published by Fusion Energy Division, Oak Ridge National Laboratory
Building 5700 P.O. Box 2008 Oak Ridge, TN 37831-6169, USA
Editor: James A. Rome Issue 122 Octobert 2009
E-Mail: jar@ornl.gov Phone (865) 482-5643
On the Web at http://www.ornl.gov/sci/fed/stelnews
Introduction of the Coordinated
Working Group Meeting
for Stellarator/Heliotron
Studies
The Coordinated Working Group Meeting (CWGM) for
Stellarator/Heliotron Studies has been active since its first
meeting in Kyoto in September 2006. The main long-term
goals of CWGM activity are to identify critical issues for
helical systems, to perform thorough and critical assessment
of data, and to define a database for system/reactor
studies. These goals can be achieved by obtaining comprehensive,
complementary, and deductive perspectives that
can provide highly reliable extrapolations. Helical system
research, by exploiting the diversity of the three-dimensional
(3D) nature of magnetic configurations, provides
the best opportunity to achieve this through joint comparative
studies. The CWGM offers an appropriate forum to
accomplish these goals. As shown in Fig. 1, CWGM meetings
have typically been held in between the major international
conferences, such as the IAEA fusion energy
conference (IAEA-FEC) and the international stellarator/
heliotron workshop (ISHW), to facilitate collaborative
research documented in joint papers. More than 10 joint
papers originating from CWGM activity have been presented
at such conferences, and seven joint papers will be
presented at the 17th ISHW in Princeton, NJ, USA. (For
reference, the joint papers presented at IAEA-FEC are
listed at the end of this article.)
The CWGM activity is briefly introduced here with the
hope of getting more researchers interested and involved,
resulting in the broadening of the activity and the expansion
of the database for future development.
Helical system research has a long history of programmatic
international collaborations. One of the formalisms
supporting such collaborations is the IEA Implementing
Agreement for Cooperation in the Development of the
Stellarator Concept, concluded by the Stellarator Executive
Committee (SEC) on 2 October, 1992.
Extensive collaborations based on the body of data arising
from multiple devices have led to what may be regarded as
a landmark achievement, the International Stellarator Scal-
Fig. 1. Evolution of the CWGM activity.
In this issue . . .
Introduction of the Coordinated Working Group
Meeting for Stellarator/Heliotron Studies
The Coordinated Working Group Meeting (CWGM) for
Stellarator/Heliotron Studies has been active since its
first meeting in Kyoto in September 2006. The main
long-term goals of CWGM activity are to identify critical
issues for helical systems, to perform thorough
and critical assessment of data, and to define a database
for system/reactor studies. ............................. 1
Announcements
Itoh Project Prize in Plasma Turbulence 2009 awarded
to Tim Happel (EURATOM-CIEMAT). ..................... 4
Fusion wiki at CIEMAT. ........................................... 4
U.S. Stellarator Engineering Metrics peer review
posted. .................................................................... 4
Stellarator News -2- Octobert 2009
ing 1995 (ISS95) [1]. The International Stellarator/Heliotron
Confinement DataBase (ISH-CDB) activity acquired
the “official” auspices of the above agreement in 2002.
Since new helical devices such as Heliotron J, HSX, LHD,
and TJ-II (in alphabetical order) came into operation after
the derivation of the ISS95, a second phase of ISH-CDB
activity was launched, to be able to explore a wider range
of configurations and plasma parameter space. The effective
helicity, as the configuration-dependent quantity, was
introduced to produce the ISS04 [2]. The trend, of better
energy confinement in the case of smaller effective helicity,
is recognized through intermachine comparison and
even in configuration scan experiments in one device.
As detailed profile information about plasma parameters
has become routinely available, qualitative upgrade of the
database activity to include profile information is possible
and expected. More physics-based discussions can be
anticipated with this upgrade. One particular example was
selected as its prototype project: plasmas having a peculiarly
steep electron-temperature gradient in the core
region, commonly obtained in CHS, LHD, TJ-II and W7-
AS (in alphabetical order) with centrally focused electron
cyclotron heating (ECH). The significance of the electron
root of the radial electric field in the core region was recognized
through comparative studies. This is a physics
mechanism peculiar to helical systems, and not the case in
tokamaks. Based on this clarification, those plasmas were
denoted as core electron-root confinement (CERC) [3],
highlighting their physics background. After this project’s
presentation at the 15th International Stellarator Workshop
(Madrid, 2005), discussions among interested volunteers
[coordinated mainly by Prof. H. Yamada (NIFS) and Dr.
A. Dinklage (IPP-Greifswald)] led to an agreement to
launch a programmatic collaboration on profile database
activity, the International Stellarator/Heliotron Profile
DataBase (ISH-PDB]). Meanwhile it was agreed to initiate
“working-basis” meetings as the supporting body of
ISH-C/P DB activities and to facilitate joint collaborations.
This is the origin of the CWGM.
Five CWGMs have been held to date (the sixth one will be
held in Princeton on 16 October 2009), as shown in Fig. 1.
In Table 1, some facts along with the topics discussed are
summarized. Although detailed discussion of each topic is
not described here, presentation materials can be obtained
through the NIFS web site, http://www.nifs.ac.jp/en/
index_cat04.html [DATABASE → International Stellarator/
Heliotron Confinement/Profile Database (ISH-C/P
DB)]. Based on the voluntary nature of contributions, not
all the topics have been continuously discussed, and the
contributors may vary from time to time. However, the
CWGM has evolved by identifying a person in charge
from each device/institution on each possible topic, to support
steady progress towards completeness.
Along with the progress of individual topics related to critical
issues in helical systems (and for tokamaks in many
cases), issues on reactor scenarios (such as HSR [4] and
FFHR [5]) and collaborations in technology fields were
also discussed at the fourth meeting, to develop concrete
action plans for system/reactor studies. Agreement was
reached to launch physics assessments of reactor scenarios
utilizing the ISH-C/P DB.
One of the advanced capabilities of the stellarator/heliotron
community, computational tools that deal rigorously
with the 3D nature of magnetic configurations, can be also
extensively applied to critical issues in the tokamak community.
One example would be the quantitative understanding
of the impacts of induced ergodization of the
edge field structure on edge-localized mode (ELM) behavior
[6]. The CWGM has provided suitable opportunities to
Table 1. Some topics of previous CWGM meetings.
1 On-site/video participants may not be counted.
# Place Date
# attendants
(on record)1
Remarks: Topics discussed etc.
(alphabetical order unless underlined)
1
Kyoto University 19–22, September
2006
41 ISS04(CDB)􀃆PDB, possible topics on collaborations, Joint
Meeting with Kinetic Theory in Stellarators
2
IPP-Greifswald 4–6, June 2007 26 Edge/3D divertor, high beta, impurity, iota/shear, momentum
transport, neoclassical (NC) transport
3
NIFS 23–24, October
2007
34 Current drive (CD), edge/3D divertor, flow/momentum transport,
high beta, high performance, impurity, iota/shear, NC,
technical issues of DB, transport codes
4
CIEMAT 20–22, October
2008
29 Reactor, collaboration on technology, 3D effects,
CD, data access, edge/3D divertor, high beta, impurity, iota/
shear, transport codes,
turbulent transport codes (􀃆 passed to discussions in
expert group)
5
Stuttgart Univ. 6–8, July 2009 29 H mode and ELM, turbulence studies (experiment), usage
of PDB, data access, high beta, iota/shear, 3D effects
Stellarator News -3- Octobert 2009
discuss strategic ways to reach out to the tokamak community,
and to deepen the understanding of helical systems as
an essential element of toroidal confinement.
Possible linkages to the International Tokamak Physics
Activity (ITPA) were also discussed at the 5th CWGM.
(For details, see for example http://itpa.ipp.mpg.de/.) Due
to a kind of “top-down” selection of issues in the case of
ITPA, it was pointed out that programmatic linkage of
CWGM to ITPA might not be plausible, at least at this
moment. However, people working on helical systems
who want to contribute to the ITPA can utilize the CWGM
to verify their results in a more comprehensive manner
(i.e., not device-specific) to increase the impact of their
results. For this purpose, inputs from the ITPA members
appointed from the stellarator community (to each topical
group) to CWGM are highly appreciated to provide crossfertilization
in both meetings.
The collection of profile data has been extended to construct
the profile database (PDB). The PDB has been
jointly hosted by IPP and NIFS, in a similar manner to the
confinement database (CDB). The web site is http://xanthippe.
ipp-hgw.mpg.de/ISS/public/index.html (IPP) and
http://ishpdb.nifs.ac.jp/index.html (NIFS). Currently, the
data are stored according to the physics topics, such as
CERC, high beta, high performance, and H mode. The
time trace of the shot, profile information (in figures as
well as in Ufiles [7], which are compatible with the international
multi-tokamak profile database [8]), and some
key profiles [e.g., radial electric field (measurement/calculations)
for CERC cases] are stored. In principle, published
data are stored for public use. The number of profile
data sets has been gradually increased to make it more
comprehensive. Anyone wishing to contribute data may
contact Dr. A. Kus (IPP-Greifswald) and/or H. Funaba
(NIFS), who are in charge of managing the database.
Meanwhile, associated configuration (equilibrium) data
are now intended to be stored, so that people who are
interested in applying their computational codes to experimental
profiles can do so. So far, only a few examples
have been provided [e.g., high-beta shots from W7-AS, by
Dr. J. Geiger (IPP-Greifswald)]. Those who voluntarily
check the database availability and send comments are
encouraged in order to realize a user-friendly database.
The registered profiles on ISH-PDB can also be utilized as
a test bed, similar to the Cyclone DIII-D base case [9],
with the equilibrium information commonly used by a
number of different computational codes.
A poster introducing the CWGM and associated database
activity will be presented at the 17th ISHW in Princeton.
You all are very welcome to join the activity to make it
more extensive and comprehensive to achieve its longterm
goals.
These activities are partly supported by NIFS (National
Institute for Fusion Science) and NINS (National Institutes
of Natural Sciences) under the project “Formation of International
Network for Scientific Collaborations.” We
appreciate the sincere efforts of Dr. B. Peterson (NIFS) at
proofreading the English.
References
[1] U. Stroth et al., Nucl. Fusion 36 (1996) 1063.
[2] H. Yamada et al., Nucl. Fusion 45 (2005) 1684.
[3] M.Yokoyama et al., Fusion Sci. Technol. 50 (2006)
327.
[4] H. Wobig et al., Nucl. Fusion 43 (2003) 889.
[5] A.Sagara et al., Fusion Eng. Design 81 (2006) 2703.
[6] See e.g., T. E. Evans et al., Nucl. Fusion 48 (2008)
024002.
[7] See e.g., http://w3.pppl.gov/~pshare/help/
ufiles_manual_toc.html
[8] The ITER 1D Modelling Working Group, Nucl. Fusion
40 (2000) 1955.
[9] A. M. Dimits et al., Phys. Plasmas 7 (2000) 969.
Joint papers presented at IAEA-FEC from the CWGM
activity:
20th IAEA-FEC (2004)
H.Yamada et al., Nucl. Fusion 45 (2005) 1684.
21st IAEA-FEC (2006)
M. Yokoyama et al., Nucl. Fusion 47 (2007) 1213.
A. Dinklage et al., Nucl. Fusion 47 (2007) 1265.
22nd IAEA-FEC (2008)
Y. Feng et al., Nucl. Fusion 49 (2009) 095002.
R. Burhenn et al., Nucl. Fusion 49 (2009) 065005.
A. Weller et al., Nucl. Fusion 49 (2009) 065016.
M. Yokoyama, on behalf of the collaborators in CWGM activity
National Institute for Fusion Science
322-6 Oroshi, Toki 509-5292, Japan
E-mail: yokoyama@LHD.nifs.ac.jp
Stellarator News -4- Octobert 2009
Itoh Project Prize in Plasma
Turbulence 2009 awarded to
Tim Happel
(EURATOM-CIEMAT)
At the 36th European Physical Society (EPS) Conference
on Plasma Physics (Sofia, Bulgaria, 29 June–3 July 2009),
the Itoh Project Prize in Plasma Turbulence 2009 was
awarded to Tim Happel (EURATOM-CIEMAT) for his
work on “Perpendicular plasma velocity and radial electric
field profiles measured by Doppler reflectometry in the
stellarator TJ-II.”
This was the fifth time that Professor Sanae-I. Itoh, in
agreement with the conference organizers and with the
help of Plasma Physics and Controlled Fusion (PCCF,
published by the Institute of Physics), has offered the Itoh
Project Prize in Plasma Turbulence to students presenting
a poster at the conference. (Please visit the PPCF web site
for previous winners.) The winner is given the chance to
visit Kyushu University in Japan for one week, including
flights and living expenses.
The competition was very successful with many excellent
candidates. Each candidate had to make a presentation of
at least 15 minutes and the final choice was very difficult.
After enthusiastic discussion, the selection committee for
2009 (S.-I. Itoh, G. Bonhomme, S. Chapman, K. Itoh, U.
Stroth) chose T. Happel as the winner.
Two students also received high commendations from the
judges:
Alessandro Casati, EURATOM-CEA Cadarache, “Turbulence
in Tore-Supra plasmas: measurements and validation
of nonlinear simulations”
Christian Theiler, EPFL, “Study of filament motion and
their active control.”
Congratulations to these students and thank you to all
entrants.
Fusion wiki at CIEMAT
A new Fusion Wiki has started at:
http://www-fusion.ciemat.es/fusionwiki/
The goals of the wiki are described in some detail in the
“About FusionWiki” section; however, in the spirit of a
wiki, these are open to discussion, as is any of the material
included.
The TJ-II page is at:
http://www-fusion.ciemat.es/fusionwiki/index.php/TJ-II
For more information, contact
Boudewijn van Milligen
E-mail: boudewijn.vanmilligen@ciemat.es
U.S. Stellarator Engineering
Metrics peer review posted
The U.S. stellarator R&D program has the following milestone:
“Issue report on engineering metrics for stellarator
complexity, for use in targeting simpler designs, September,
2009.” Here “metrics” is interpreted to include design
criteria, guidelines, limits, constraints, etc., as long as they
are specific enough to be incorporated into stellarator
design tools and processes. In fiscal year 2009, the first
year of the study, the goal was to make progress in documenting
metrics that could be tested in design studies the
following year. Tom Brown leads the effort to achieve this
milestone. The purpose of this peer review was to communicate
progress and utilize the technical expertise of a
broader group before finalizing the milestone report. The
report is posted at
http://nsdr.pppl.gov/meetings/aug20PeerRev/
Stel_MetricsRev.pdf
Fig. 1. Tim Happel (left) is announced as the winner by
Prof. Sanae-I. Itoh.

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