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U.S. Burning Plasma Organization eNews
February 18, 2010 (Issue 41)

CONTENTS

Director's Corner
Jim Van Dam
USBPO Topical Group Highlights new  
Plasma Profile Prediction using TGYRO/GYRO/NEO
by Jeff Candy
Reports
Meeting of the ITPA Divertor/SOL Group
by Bruce Lipschultz, Emmanuelle Tsitrone, and Richard Pitts
Upcoming Burning Plasma-related Events
2010 Events
2011 Events

 

Dear Burning Plasma Aficionados:

This newsletter provides a short update on U.S. Burning Plasma Organization activities. Comments on articles in the newsletter may be sent to the editor (Tom Rognlien trognlien at llnl.gov) or assistant editor (Rita Wilkinson ritaw at mail.utexas.edu).

Thank you for your interest in Burning Plasma research in the U.S.!

 

Director's Corner by J. W. Van Dam

Research Highlights in eNews
Beginning with this issue, eNews plans to feature brief research highlight articles each month. The topics will be solicited from the leaders and members of the USBPO Topical Groups (http://burningplasma.org/groups.html), as well as through individual submissions to the editor. The first such research highlight write-up, which appears in this issue, was contributed by the Modeling and Simulation Topical Group. Please contact Tom Rognlien, eNews editor, if you have recommendations for future research highlight summaries.

Burning Plasma Papers for the IAEA Fusion Energy Conference
Instructions about submitting abstracts and synopses for burning plasma and ITER-related papers for the IAEA Fusion Energy Conference (October 11-15, 2010, Daejeon, Korea) have come both from the US Paper Selection Committee and the ITER Organization. For papers with US scientists as primary authors, here is a quick summary.

  • Burning plasma papers: The two-page extended synopses and short abstracts for such papers were supposed to have been submitted to the U.S. Paper Selection Committee by February 8. Dr. John Mandrekas at the Office of Fusion Energy Sciences is the chair of this committee.

  • ITER-related papers: Synopses and abstracts for U.S. papers describing ITER-related research should also have been sent to the U.S. Paper Selection Committee by this date. The committee will send a list of the papers that are specifically related to ITER physics and technology to the US ITER Project Office, to be forwarded to the ITER Organization, which has set up its own Paper Review Committee.

  • ITPA papers: These papers are to be submitted directly to the ITER Organization by February 21. However, the US Paper Selection Committee has asked to receive copies of the abstracts and synopses for such papers by February 19, for the sake of information.

The US Paper Selection Committee will meet on February 22-23 in the Washington, DC area.

The ITER Paper Review Committee consists of ITER staff scientists and representatives of the seven ITER domestic agencies. The chair of the committee is Valery Chuyanov (ITER). The domestic agency representatives are Yuntao Song (China), Paul Thomas (European Union), Indranil Bandyopadhyay (India), Yoshinori Kusama (Japan), Hyeon Gon Lee (Korea), Aleksandr V. Zvonkov (Russian Federation), and Nermin Uckan (US). This committee will recommend papers for the ITER session at the Fusion Energy Conference, as well as papers for the Introductory, Overview, and Poster sessions. The recommendations will be issued by March 11.

Instructions for all authors can be found at the Fusion Energy Conference web site
(http://wwwpub.iaea.org/MTCD/Meetings/Announcements.asp?ConfID=38091); in particular, see the files entitled Annex A and Annex B. Synopses and abstracts of papers either selected by the US Paper Selection Committee or recommended by the ITER Paper Review Committee are to be submitted to the conference web site by April 2.

4th International ITER Summer School
The University of Texas at Austin will host the 4th International ITER Summer School on campus at the AT&T Conference Center, May 31-June 4, 2010. The theme of this year’s Summer School is“Magnetohydrodynamics and Plasma Control in Magnetic Fusion Devices.”

iiss2010

This weeklong Summer School typically attracts about 100 graduate student students and 20 lecturers from Europe, Japan, USA, China, Korea, India, and Russian Federation. The School’s purpose is to train young researchers in the physics of burning plasmas and prepare them to contribute to the ITER scientific program. Sponsors of the 2010 ITER Summer School will be the US Burning Plasma Organization, National Instruments Corporation, University of Provence, and the American Physical Society. The Institute for Fusion Studies of The University of Texas at Austin is coordinating the School. Past ITER Summer Schools have been held at Cadarache, France (2007), Kyushu, Japan (2008), and again at Cadarache (2009). For more information, contact the summer school joint director, Professor Wendell Horton (ritaw@mail.utexs.edu) or visit the summer school web site (http://w3fusion.ph.utexas.edu/ifs/iiss2010/). Participants are asked to register online for the ITER Summer School by April 30.

Leadership Changes at US ITER Project Office
Recently there have been some personnel changes at the USIPO. John Miller, manager for Magnet Systems, retired at the end of January; Wayne Reiersen, USIPO Systems Engineering, will replace him on an ad interim basis. Another Wayne, namely, Wayne Steffey, has been promoted to Project Controls Director; he succeeded Suzanne Herron, who had been named Deputy Project Director in October 2009, after Carl Strawbridge retired from that position.

Upcoming ITER Meetings
Here is a short list of some important ITER meetings that are coming up this year:

  • Heads of Delegation Meeting (February 23-24, Paris)

  • Special Management Advisory Committee Meeting (tentatively March 10-11, Cadarache)

  • Workshop on TBM Impact on ITER Plasma Physics and Potential Countermeasures (April 13-15, Cadarache)

  • Science and Technology Advisory Committee Meeting (May 19-21, Cadarache)

  • Management Advisory Committee Meeting (May 25-26, Cadarache)

  • ITER Council Meeting (June 16-17, Suzhou, China)

  • Integrated Modeling Expert Group Meeting (week of September 13, exact dates to be determined)

Last Reminder: ITER Booth at AAAS Meeting
The US ITER Project Office will have a display booth at the AAAS Meeting (18-22 February, San Diego, http://www.aaas.org/meetings/2010/). If any of you plan to be at the meeting and could spare a few hours to help staff the ITER display booth, please contact Bonnie Hebert at the USIPO (865-574-8381, hebertb@ornl.gov). She will set up the schedule and provide any instructions.

Fusion on YouTube
A recent note from the Fusion Power Association recommended the following YouTube links for an“informative, entertaining, and educational look at the story of fusion in six parts”:

Note, too, that many videos about ITER are available on the ITER Media Page web site (http://www.iter.org/org/team/odg/comm/Pages/Video.aspx).

USBPO Topical Group Highlights

The Modeling and Simulation Topical Group ( Leaders, Don Batchelor and Dylan Brennan) seeks to facilitate U.S. efforts in large-scale computations that are relevant to multiple topical groups within the BPO and to coordinate those efforts with ITPA and ITER Integrated Modeling Expert Group (IMEG) activities. The following research highlight from Jeff Candy is an example of recent progress in just such an area.

Plasma Profile Prediction using TGYRO/GYRO/NEO
by Jeff Candy (General Atomics)

Hundreds of massively parallel gyrokinetic and neoclassical simulations are coordinated to predict steady-state plasma temperature and density.

The confinement of tokamak plasma is known to be limited by the presence of transport driven by fine-scale turbulence. For roughly a decade, gyrokinetic codes have existed which can simulate the evolution of this turbulence by direct numerical simulation. These codes, however, are restricted insofar as they take plasma profiles of temperature and density as given, and evolve the turbulent system for a very short time (typically less than a millisecond). While these studies have shed light on both generic features of the turbulence as well as the parametric scaling of transport with plasma parameters, they are not predictive. That is, after a period of time on the order of seconds, the plasma profiles evolve to a self-organized state in which heat loss from transport will balance the heat input from external heating sources (or from thermonuclear reactions in the case of a reactor). Simulating this approach to the steady state, and determining the steady-state plasma profiles, has heretofore only been possible with reduced models, which often make severe approximations and neglect key features of the problem in order to maintain computational tractability.

torus

Direct numerical simulation of turbulent density fluctuations by the General Atomics GYRO code. Hundreds of such simulations are necessary to determine the self-consistent plasma profiles.

Using the newly developed TGYRO code, which integrates GYRO gyrokinetic simulations and NEO neoclassical simulations, researchers at General Atomics have been able to address the problem of profile prediction from first-principles. To do this, one must be able to execute hundreds (or perhaps thousands) of independent direct simulations to accurately home in on the physically-important steady-state solution. This approach to the problem is now possible as a result of significant algorithmic advances in the General Atomics turbulence code, GYRO, combined with access to ever-expanding computational resources. The result of some recent simulations, which took the experimental heating power as an input, showed satisfying agreement with the experimentally-measured temperature profiles. The simulations took nearly 30 hours of wall clock time using around 1500 cores, mounting to tens of thousands of CPU hours to predict the steady state. These results were presented at the American Physical Society Division of Plasma Physics annual conference, in Atlanta, Georgia, November 2009.

chart

Simulation results (red) versus experimental data (blue) for ion temperature (top), electron temperature (middle) and electron density (bottom) and electron (right) for DIII-D L-mode discharge 128913. The TGYRO solutions in red represent a steady-state.

Work is presently underway to include a prediction of the electron plasma density as well as the plasma rotation rate. When this capability has been perfected, researchers will turn their attention to the problem of profile prediction in envisioned energy-producing reactor plasmas like the ITER device scheduled to begin operation 8+ years from now.

Work supported by the U.S. Department of Energy under DE-FG03-95ER54309 and DE- FG02-07ER54917, and used the resources of the NCCS at ORNL under contract number DE-AC05-00OR22725.

Reports

Meeting of the ITPA Divertor/SOL Group
Contributed by Bruce Lipshultz (Massachusetts Institute of Technology), Emmanuelle Tsitrone (Commissariat à l'Energie Atomique et aux Energies Alternatives), Richard Pitts (ITER Organization)

The 13th meeting of the ITPA Divertor/Scrape-Off-Layer (Div/SOL) Group was held December 14-17, 2009, in San Diego with over 50 participants. The technical sessions can be roughly divided into two main areas: (1) material response to incident plasma and (2) edge/SOL plasma characteristics that determine those fluxes—though some overlap both areas. For the material response area, an overview some of the main results presented and discussed follows:

  • The impact of the substrate temperature on both fuel (deuterium/tritium [D/T]) retention in co-deposits and their removal is a key question, with retention issues being the subject of previous meetings and removal issues the subject of this meeting. When one examines hydrogen/beryllium (H/Be) co-deposition with low carbon (C) fractions (below a few percent) the co-deposits act like pure Be in that ~90% of the H can be desorbed at bakes of 350° C. However, for higher C concentrations in the co-deposits, carbides form, which means both that there is less initial retention in the co-deposit and almost none of the retained H is removed up to 1000° C. Oxygen-radicals produced by electron cyclotron resonance discharges were reported to be efficient at removing C from gaps.

  • Presentations reviewed information in Be erosion in tokamaks and laboratory devices. The results were not in good agreement with one another, meaning that predicting the lifetime of the Be wall in ITER, and its role in co-deposition, has very large uncertainties. It was agreed that further laboratory studies are needed together with upcoming work for the JET ITER-like wall (ILW) experiments. An informal (non-Div/SOL) collaboration was initiated between UCSD, Sandia-Livermore, and FOM to investigate Be (and possible Be surrogate materials such as Al and Mg) erosion mechanisms. In addition, the experiments planned for the EAST tokamak in China should help bring new information on material migration to benchmark code calculations.

  • The ITER IO has decided that a tungsten (W) divertor will be utilized in that device before the DT phase. Because W will then be in the region where the magnetic separatrix intersects the divertor plate, the plasma power exhaust will be concentrated here. Thus, W melting is very likely, and understanding the processes is receiving more emphasis. A model of the observed dynamics of melted W surfaces in TEXTOR is consistent with thermal emission current crossed with the magnetic field moving the melted W up the tile against gravity. The re-solidified W exhibits a porous structure, and laboratory analysis of neutron-irradiated W and C can show degraded material performance. Initial experiments of a divertor-localized W source in ASDEX-Upgrade show minimal impact on the core plasma. A number of new W materials (alloys or specially prepared W) were discussed and more work is needed in this area. The W nano-structures (“fuzz”) seen in laboratory plasmas are being investigated in tokamaks where their growth may be prevented by ion erosion, deposition of low-Z wall materials, or high plasma pressure.

  • Dust formation and entry into the plasma are topics that bridge the materials/SOL areas. The ITPA Div/SOL joint tokamak experiment activity here is referred to as DSOL-21. Very similar dust injections have been performed on a number of tokamaks (e.g., MAST, DIII-D, TEXTOR) and the results indicate a dependence of the trajectory on the mass/nuclear-charge of the material. For modeling comparison, more effort is needed to understand the initial velocity/direction of the particles because results are sensitive to this feature. Understanding the mechanisms for dust generation is still in an infant state due to lack of diagnostics, though gridded analyzers and quartz micro-balances for dust under tile gaps have some promise.

Some of the main results for the edge/SOL plasma area are as follows:

  • Power flow during disruptions was reviewed. While several tokamaks have added main chamber infrared (IR) views of material surfaces, the results are sparse. The variation can be large; DIII-D reported a range of x1000 for divertor power loads during the thermal quench (TQ) for different kinds of disruptions, with plasma-beta limit disruptions being the worst. The new IR system on JET indicates that first-wall energy deposition during a disruption can approach that at the divertor. Here coordination with the MHD group would enhance the information available.

  • Experiments on disruption mitigation benefited from a significant enhancement of diagnostic capability over the last year, resulting in observations of toroidal and poloidal asymmetries in the induced radiation following massive gas injection (MGI). Although there are some small discrepancies between the experiments, there is an overall agreement that MGI gives a significant reduction of localized, conducted heat loads to the first wall and divertor. AUG, JET, and DIII-D all report that the injected impurities are swept by poloidal drifts over the top (crown) of the plasma toward the inner wall. This observation raises the concern that a repeatable "hot spot" may form. However, results from C-Mod show that the toroidal asymmetry of the thermal quench radiation flash is quite variable, suggesting that repeated radiation flash heating of a single wall location during the TQ is unlikely. Overall, there was a consensus that more and better timeresolved bolometry of MGI shots should be done. Also, experiments with simultaneous MGI at two different toroidal locations were recommended, thus helping to verify that ITER radiation flash heat loads can be broadened by use of multiple MGI ports.

  • The study of the effect of RMP on heat loads and the SOL profiles is only in its infancy. The little information we have garnered so far seems to indicate the SOL is not strongly affected, though the SOL profiles appear to revert to being L-mode-like. More data is needed from the various experiments.

  • The current dataset for limiter plasma SOL profiles was reviewed. While the data is consistent with models, the consistency seems poor—the implication being that either a first-principles model is needed, or better data from a range of tokamaks. Certainly, better measurements of ion temperature are needed to understand the ion power flow channel. With regard to the question of the effect of species (H, D, He) on SOL profiles, the answer is minimal with some plasma profile broadening reported for JET helium (He) plasmas. Lastly, the scaling of ELM power flows to main chamber walls was examined in JET as a function of ΔW/W, the fractional energy lost during an ELM. Since larger ELMs carried a bigger fraction of their energy to the outer SOL, data is needed from multiple machines, together with better modeling, to determine how this effect scales to ITER.

The next ITPA Div/SOL meeting is planned to be near the time of the IAEA Fusion Energy Conference in October 2010.

Announcements

Submit BPO-related announcements for next month’s eNews to Tom Rognlien at trognlien at llnl.gov.

 

Upcoming Burning Plasma Events

 
2010 Events
 
February 16-19
Innovative Confinement Concepts Workshop (ICC 2010)
(abstracts due Dec. 4)
Princeton, New Jersey USA
 
March 8-12
ITPA MHD Topical Group Meeting
NIFS, Japan
 
Week of 22 March
ITPA Transport & Confinement Topical Group Meeting
Oxfordshire, UK
 
April 12-15
16th Joint Workshop on Electron Cyclotron Emission and Electron Cyclotron Resonance Heating
Sanya, China
 
April 13-15
ITER "Workshop on TBM Impact on ITER Plasma Physics and Potential Countermeasures"
Contributors contact: Joseph.Snipes@iter.org and Luciano.Giancarli@iter.org by Jan. 22
Cadarache, France
 
April 13-16updatedNOTE DATE CORRECTION
U.S. Transport Task Force Workshop
(abstracts due Feb. 19)
Annapolis, Maryland USA
 
April 13-16
International Conference on Plasma Diagnostics
Pont-à-Mousson, France
 
April 19-21
Sherwood Fusion Theory Conference
(abstracts due Feb. 16)
Seattle, Washington USA
 
April 20-23
Integrated Operational Scenarios ITPA Meeting
Princeton, New Jersey USA
 
April 21-23
ITPA Pedestal Topical Group Meeting
Naka, Japan
 
May 10-14
18th ITPA Diagnostics Topical Group Meeting
Oak Ridge, Tennessee USA
 
May 16-20
18th HTPD Topical Group Meetings
Wildwood, New Jersey USA
 
May 19-21
STAC-8
Cadarache, France
 
May 24-28
19th International Plasma Surface Interactions Conference
(abstracts due Nov. 20)
San Diego, California, USA
 
May 31-June 4
4th ITER International Summer School
(abstracts due April 30)
Austin, Texas USA
 
June 20-24updatedNOTE DATE CORRECTION
37th IEEE International Conference on Plasma Science (ICPOS 2010)
(abstract submission extended to Jan. 23)
Norfolk, VA USA
 
June 21-25
37th European Physical Society Conference on Plasma Physics
(abstracts due Feb. 27)
Dublin, Ireland
 
Aug 30-Sept 3
Theory of Fusion Plasmas Joint Varenna-Lausanne International Workshop
(abstracts due June 18)
Varenna, Italy
 
Sept 27-Oct 1
26th Symposium on Fusion Technology (SOFT2010)
Porto, Portugal
 
Oct 11-16
23rd IAEA Fusion Energy Conference
(U.S. synopsis due Feb. 8)
Daejeon, Korea
 
Oct 24-29
9th International Conference on Tritium Science and Technology
Nara, Japan
 
Nov 7-11
19th Topical Meeting on the Technology of Fusion Energy (TOFE 2010)
(embedded with 2010 ANS Winter Meeting)
Las Vegas, NV
 
Fall
ITPA Transport and Confinement Topical Group Meeting
(following IAEA)
South Korea
 
Fall
ITPA IOC Topical Group Meeting
(following IAEA)
South Korea
 
Fall
ITPA Diagnostics Topical Group Meeting
(following IAEA)
Japan
 
2011 Events
 
Spring
ITPA Transport & Confinement Topical Group Meeting
(following US/EU TIF)
San Diego, California USA

Click here to visit a Directory of Other Plasma Events

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