Center for Gyrokinetic Particle
of Turbulent Transport in Burning Plasmas
(for FY2005 - FY2007)
Note: This SciDAC Center is now in process of recompetition by a
new team headed by P. Diamond (UCSD), for FY2008 on.
[A twisted mesh structure is used in the shaped GTC simulation]
[Figure featured on cover of Battelle Annual Report - 2006]
PI's | About the Center | Organizational Chart | Activities
Dr. W. W. Lee, Princeton Plasma Physics Laboratory, Princeton, NJ
Prof. S. E. Parker, University of Colorado, Boulder, CO
Prof. Z. Lin, University of California, Irvine. CA
Dr. V. K. Decyk, University of California, Los Angeles, CA
Prof. D. E. Keyes, Columbia University, New York, NY
Prof. M. Beck, University of Tennessee, Knoxville, TN
Prof. K.-L. Ma, University of California, Davis, CA
Dr. S. Klasky, Princeton Plasma Physics Laboratory, Princeton, NJ
The "Center for Gyrokinetic Particle Simulation for
Turbulent Transport in Burning Plasmas" has recently been selected by the
Department of Energy's program of "Scientific Discovery through Advanced
Computing (SciDAC) – Advanced Simulation of Fusion Plasmas". Dr. W. W.
Lee of the Princeton Plasma Physics Laboratory (PPPL) at Princeton University is
the head of this new national center, which includes strong collaborations with
Columbia University, University of Colorado, University of Tennessee, and the
University of California campuses at Irvine, Los Angeles, and Davis. It is a
program that brings together leading experts in plasma simulation, theory, and
computational sciences to address the grand scientific challenge of achieving
better understanding of turbulent transport in fusion plasmas for: 1) the
parameter regimes relevant to magnetic fusion experiments such as the
International Tokamak Experimental Reactor (ITER), and 2) to lay the groundwork
for an integrated fusion simulation project in the future.
Significant progress in gyrokinetic particle simulation of
turbulent transport has been made since the SciDAC Plasma Microturbulence
Project (PMP) was launched nearly three years. For example, effective
utilization of the full power of the fastest unclassified supercomputers has
enabled first-principles kinetic simulation of the electrostatic ion temperature
gradient (ITG) drift turbulence in a reactor-scale plasma using our global
gyrokinetic toroidal code (GTC), and the development of advanced algorithms has
made possible the implementation of the electron dynamics in the PMP codes.
Nonetheless, many fundamental issues in turbulent transport remain unresolved
and the extrapolation of plasma confinement properties of existing experiments
to the parameter regimes for burning plasmas is not fully justified. At present,
none of the existing gyrokinetic (particle-in-cell or continuum) turbulence
simulation codes in the fusion programs around the world can, as yet, address
adequately and efficiently the scientific challenges critical to the success of
a burning plasma experiment.
The present project will further develop the state-of-the-art
capabilities based on particle-in-cell simulation techniques; i.e., a
global code (GTC) complemented by an electromagnetic flux-tube code (GEM). The
GTC code has been optimized to achieve high efficiency on a single computing
node and nearly perfect scalability on both massively parallel computers (MPP)
such as the IBM SP at the National Energy Research Supercomputing Center (NERSC)
and parallel vector computers such as the Earth Simulator Computer (ESC) in
Japan. Because of its excellent performance and scalability, GTC has been
selected as the fusion code in the NERSC benchmark suite for assessing
performance on advanced computational platforms, including the ESC and the CRAY
X1 at ORNL. At present, it is the only US fusion code that has actually been
used for benchmarking on the Earth Simulator Computer. The scientific challenges
the Center faces are far beyond the usual domain of "plasma microturbulence."
Our research would bring together coupled physics processes, which occur on
disparate spatial and temporal scales (microturbulence vs. MHD, local vs.
global) and in distinctly different regions (core vs. edge) in a fusion reactor.
This work-scope addresses a crucial step toward an integrated fusion
simulation project in the future.
In order to accelerate progress in a timely and
cost-effective way, the basic approach advocated in the original charter for DOE’s
SciDAC Program is an excellent fit for the present project. Specifically, a
multi-disciplinary collaboration involving advanced simulations, analytic
theories, experimental comparisons, applied mathematics, and computer sciences
is necessary to tackle the extraordinary complexity of plasma turbulence. The
Co-PIs of this proposal have all been actively engaged in productive
collaborations with both theorists and experimentalists for formulating physics
models, interpreting simulation results, and guiding experimental measurements.
The simulation code validation will proceed at three levels: 1) code-code
benchmarking; 2) rigorous simulation-analytic theory cross-checks; and 3)
simulation-experimental comparisons with predictive capabilities. The
comparisons between the existing global particle codes such as GTC, GT3D (Japan)
and LORB5 (Switzerland) have been an ongoing and productive process.
Motivated by the fact that the computational grand challenge
of simulating plasma turbulence inevitably pushes the limits for both the
computing hardware and software, the SciDAC Co-PIs of this project have actively
engaged in the applied math and computer sciences community. The capability of
the massively parallel turbulence simulation codes and the ability to extract
physics from large datasets will be greatly enhanced by effectively leveraging
the expertise and resources from leading applied mathematicians and computer
scientists. Accordingly, our Co-PIs in the Scientific Application Partnership
Program (SAPP) are leading experts in applied mathematics, visualization, and
data management. Their participation will undoubtedly keep this project at the
forefront of fusion research.
At the 2004 APS/DPP meeting, two invited papers, which are expected to have
significant influence on future directions in research on plasma turbulence,
will be presented by members from the Center. The talks will focus on new
results obtained from applications of the Global Gyrokinetic Toroidal Code (GTC)
on the IBM SP Seaborg computer at the National Energy Research Supercomputing
Center (NERSC) in Berkeley, California. Prof. Z. Lin [paper NI1.003] of UC
Irvine will address a subject of very active current interest -- the question of
whether electron temperature gradient (ETG) driven turbulence can contribute
strongly to the anomalously large levels of transport observed in toroidal
plasma experiments. Recent results from applications of the GTC code together
with newly-developed nonlinear gyrokinetic theory indicate that the ETG
instability saturates at low levels via a nonlinear toroidal coupling. As
illustrated in the figure,
it is found that while the lengths of the extended eddy structures
("streamers"), which characterize the ETG turbulence, scale with the
device size, the actual radial distance of the electron excursions is found to
be much smaller and diffusive. Both the fluctuation intensity and associated
transport level are thus independent of the size of the streamers. When compared
to earlier radially-local ("flux tube") simulation results, the
present finding is that the electron heat conductivity from ETG turbulence is
much smaller and is therefore not likely to be responsible for the large
anomalous electron thermal transport in toroidal devices.
Dr. W. W. Lee [paper FI1B.003] of PPPL will report on important recent
results dealing with the physics of steady state transport produced from the ion
temperature gradient (ITG) driven instabilities. The key finding here is that
appropriate treatment of the parallel acceleration dynamics produces much faster
access to the steady state of the ITG turbulence when compared with conventional simulations. These more careful studies now
include the velocity space nonlinearity, which apparently acts in concert with
the zonal flow in the evolution of steady state turbulence. The resulting
perturbed potentials for the case without the parallel velocity space
nonlinearity is on the left and that with the nonlinearity is on the right.
GPS Center Activities:Talks | Meetings | Exchanges | Publications | Links | Other
PSACI PAC 2007 Oral Talk - W.W. Lee
IAEA 2006 Oral Talk - W.W. Lee
IAEA 2006 Oral Talk - W.X. Wang
SciDAC 2006 Oral Talk - W.W. Lee
IAEA 2004 Oral Talk - Z. Lin (Power Point)
IAEA 2004 Oral Paper - T.S. Hahm (PDF)
APS/DPP 2004 Invited Talk - Z. Lin (Power Point)
APS/DPP 2004 Invited Talk - W.W. Lee (PDF)
Center for Gyrokinetic Particle
Simulation (PSACI PAC 2004 presentation) - W.W. Lee
Numerical Methods for Plasma Astrophysics: From Particle Kinetics to MHD (PICSciE04 October 25-27, 2004 presentation) - W.W. Lee
The third GPSC meeting associated with the 2006
APS Meeting took place in Philadelphia, PA, and
here is the agenda.
The second semi-annual meeting associated with the 2006
Sherwood conference was held in Dallas, Texas on April 21, 2006. An agenda
The second GPSC meeting associated with the annual APS
meeting took place in Denver, CO and
here is the speaker's list.
The first semi-annual meeting took place the week
of February 21, 2005 in Irvine, CA. Prof. Zhihong Lin of UC-Irvine was the local Chairman.
The meeting consisted of one day of tutorial talks, two days of contributed
talks and two days of working sessions, with nearly fifty people in attendance.
Click here for the meeting agenda.
The first get-together for the GPS center took place during the APS/DPP meeting on Wednesday, Nov. 17, 2004 from 5:00 - 7:00 pm
the Riverscape Room, the Westin Savannah Harbor Golf Resort and Spa, Savannah,
GA. Click here to view the meeting minutes.
Dr. Viktor Decyk of UCLA visited PPPL from 2/2 - 2/3/05
to discuss team-coding with PPPL's members of the GPS Center.
Dr. Yasutaro Nishimura, visited PPPL from 10/24/04 to
11/5/04 to work with with Mark Adams and
others in the GPSC/PPPL group.
Publication list for FY2005-FY2007 (currently 67 publications):
GPSC Bibliography (2004 - 2007) (PDF)
Phys. Plasmas 2007 paper - Y. Nishimura et al (PDF)
Phys. Plasmas 2006 paper - I. Holod & Z. Lin (PDF)
Phys. Plasmas 2006 paper - T.G. Jenkins & W.W. Lee (PDF)
IAEA 2004 paper - Z. Lin et al. (PDF)
For additional U.C.-Irvine papers go to:
UCI Plasma Theory
GPSC/UCI Theory Homepage
GPSC/Columbia Theory Homepage
UCSD Fusion/Plasma Theory Group
"The Gyrokinetic Particle Simulation Center Project: Simulating Star Power", SciDAC Review 1, 40-49 (Spring 2006)
New Insight for Plasma Turbulence (Virtual Pressroom for 2004 APS/DPP Conference)
This website is maintained by Jennifer Jones.