Simulation of Fusion Plasmas: Current Status and Future Direction
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Plasma Science and Technology, Vol.9, No.3, Jun. 2007 Simulation of Fusion Plasmas: Current Status and Future Direction D.A. Batchelor1,M.Beck2, A. Becoulet3,R.V.Budny4, C.S. Chang5, P.H. Diamond6,J.Q.Dong7,G.Y.Fu∗4, A. Fukuyama8,T.S.Hahm4, D.E. Keyes9,Y.Kishimoto10,S.Klasky1,L.L.Lao11,K.Li12,Z.Lin∗13, B. Ludaescher14,J.Manickam4,N.Nakajima15, T. Ozeki16,N.Podhorszki14, W.M. Tang4,M.A.Vouk17,R.E.Waltz11,S.J.Wang18, H.R. Wilson19,X.Q.Xu20, M. Yagi21,F.Zonca22 1 Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 2 1122 Volunteer Blvd, Suite 203, Knoxville, TN 37996-3450, USA 3 Association EURATOM-CEA sur la Fusion Contrˆol´ee, CEA Cadarache, 13108 Saint Paul lez Durance Cedex, France 4 Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543, USA 5 Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, NY 10012, USA 6 University of California at San Diego, Dept. of Physics and Center for Astrophysics and Space Sciences, La Jolla, CA 92093, USA 7 Southwestern Institute of Physics, Chengdu 610041, China 8 Department of Nuclear Engineering, Kyoto University, Kyoto 606-8501, Japan 9 Columbia University, Department of Applied Physics and Applied Mathematics, MC 4701, New York, NY 10027, USA 10 Department of Fundamental Energy Science, Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan 11 General Atomics, P.O. Box 85608, San Diego, CA 92186, USA 12 Department of Computer Science, Princeton University Princeton, NJ 08544, USA 13 Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA 14 Department of Computer Science University of California, Davis, CA, 95616, USA 15 National Institute for Fusion Science, Toki, Gifu 509-5292, Japan 16 Japan Atomic Energy Agency, Naka Fusion Research Establishment, Naka-machi, Ibaraki-ken, Japan 17 Department of Computer Science, North Carolina State University, Raleigh, NC 27695, USA 18 Department of Physics, Fudan University, 200433 Shanghai, China 19 Department of Physics, University of York, Heslington, York YO10 5DD UK 20 Lawrence Livermore National Laboratory, Livermore, CA 94550, USA 21 Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan 22 Associazione Euratom-ENEA sulla fusione, CR Frascati, Casella Postale 65-00044, Frascati, Italy To whom correspondence should be addressed. E-mail: [email protected]; [email protected] Batchelor D.A. et al.: Simulation of Fusion Plasmas: Current Status and Future Direction I. Introduction (Z. Lin, G. Y. Fu, J. Q. Dong) II. Role of theory and simulation in fusion sciences 1. The Impact of theory and simulation on tokomak experiments (H.R.Wilson,T.S.HahmandF.Zonca) 2. Tokomak Transport Physics for the Era of ITER: Issues for Simulations (P.H. Diamond and T.S. Hahm) III. Status of fusion simulation and modeling 1. Nonlinear Governing Equations for Plasma Simulations (T. S. Hahm) 2. Equilibrium and stability (L.L. Lao, J. Manickam) 3. Transport modeling (R.E. Waltz) 4. Nonlinear MHD (G.Y. Fu) 5. Turbulence (Z. Lin and R.E. Waltz) 6. RF heating and current drive (D.A. Batchelor) 7. Edge physics Simulations (X.Q. Xu and C.S. Chang) 8. Energetic particle physics (F. Zonca, G.Y. Fu and S.J. Wang) 9. Time-dependent Integrated Modeling (R.V. Budny) 10. Validation and verification (J. Manickam) IV. Major initiatives on fusion simulation 1. US Scientific Discory through Advanced Computing (SciDAC) Program & Fusion Energy Science (W. Tang) 2. EU Integrated Tokamak Modelling (ITM) Task Force (A. Becoulet) 3. Fusion Simulations Activities in Japan (A. Fukuyama, N. Nakajima, Y. Kishimoto, T. Ozeki, and M. Yagi) V. Cross-disciplinary research in fusion simulation 1. Applied mathematics: Models, Discretizations, and Solvers (D.E. Keyes) 2. Computational Science (K. Li) 3. Scientific Data and Workflow Management (S. Klasky, M. Beck, B. Ludaescher, N. Podhorszki, M.A. Vouk) 4. Collaborative tools (J. Manickam) 313 Plasma Science and Technology, Vol.9, No.3, Jun. 2007 I Introduction sults, and constructing physics models. (Z.Lin,G.Y.Fu,J.Q.Dong) ITER simulations focus on the extension of cur- rent simulation capabilities into the burning plasma After half a century of intense pursuit, magnetic fu- regime and on integrated simulations addressing simul- sion has made tremendous progress toward the goal as taneously multiple scales and multiple processes in fu- an attractive energy solution for the world’s increas- sion plasmas. A central theme is the predictive sim- ingly critical energy problem. The key obstacle for ulation integrating both modeling and physics simula- reaching the ignition has been the lack of fundamental tion codes for the purpose of benchmarking on existing understanding, and thus the limited ability to control tokamak experiments, with the ultimate goal of pro- the complex, nonlinear, and dynamical system char- viding a comprehensive simulation package for ITER acteristic of high temperature plasma in fusion toka- plasmas. Major initiatives toward integrated simula- mak experiments. Renewed optimism in magnetic con- tion with predictive capability have been launched by finement has come from recent progress marked by the several ITER partners. In US, large scale fusion sim- strong coupling between experiment, theory, and sim- ulation projects including nonlinear MHD, turbulent ulation. In particular, large-scale simulations enabled transport, RF-heating, and other areas are currently by the ever increasing power of modern computers are supported as part of the Scientific Discovery through rapidly advancing fusion energy science. Numerical Advanced Computing (SciDAC) initiative funded by simulations, in tandem with analytic theories and ex- the Department of Energy (DOE). Each project typ- perimental measurements, have helped to discover fun- ically involves 15-30 researchers in 5-10 institutions. In damental physics in fusion plasmas, to understand toka- addition to addressing key science area, fusion SciDAC mak experimental results, to guide the design and in- supports three prototype centers for a fusion simula- stallation of advanced tokamak diagnostics, to control tion project (FSP) targeting integrative simulation of plasma behavior, and to optimize tokamak operation burning plasmas. The burning Plasma Simulation Ini- regimes. tiative (BPSI) organized as joint university group, the The International Thermonuclear Experimental Re- Numerical Experiment of Tokamak (NEXT) organized actor (ITER) experiment is the crucial next step in the by JAEA, and the multi-scale fusion plasma simulation quest for fusion energy. Theory and simulation will organized by the NIFS group, have been proposed in play an even bigger role in the ITER project as we ex- Japan, which may play a central role for the ITER sim- plore the new regime of burning plasma physics. First- ulation center for fusion science. The European Union principles simulations could directly address the param- (EU) has launched an Integrated Tokamak Modeling eter regimes inaccessible by conventional experimental (ITM) initiative in Europe for ITER. and analytic techniques. Predictive simulation tools Addressing the dynamical processes in fusion plas- could enhance the efficiency of the utilization and opti- mas characterized by a large number of degree of free- mize operation configurations for ITER, and could aid dom and disparate spatial-temporal scales, fusion sim- the physics design of DEMO, the successor to ITER for ulation is a grand challenge from both the physics the engineering demonstration of a fusion power plant. and computing points of view. Consequently, cross- Fusion simulations fall broadly into two categories. disciplinary collaboration has become a clearly visible The first type, referred to as “modeling” in this pa- trend in fusion simulations, which often involve com- per, is a reduced model incorporating all known physics putational and analytical plasma physicists, applied and empirical scaling for unknown physics. Examples mathematicians, computational and computer scien- include the re-construction of magnetohydrodynamic tists. Therefore, it is crucial to carefully plan the co- equilibrium and transport modeling. Modeling is the ordination and collaboration across the boundaries of essential tool for assisting experimental operations and disciplines and institutions. Another important obser- data interpretation, and for projecting the performance vation is that fusion simulation is one of the key applica- of future burning plasma experiments. These areas are tions driving the hardware and software developments relatively mature thanks to research efforts over the for high performance computers. Large-scale physics past three decades. The second type, referred to as simulations can effectively utilize the computing power “physics simulation”, is a direct numerical simulation of thousands of processors using the most powerful mas- using first-principles equations. The goal is to identify sively parallel computers. and discover the fundamental physics in fusion plas- Recognizing the importance of theory and simulation mas, and to provide a physics basis for innovative con- in fusion research and the collaborative nature of ITER finement approaches and advanced operation regimes. simulation, a Workshop on ITER Simulation sponsored Such physics simulations provide the building blocks for by the ITER-China participation team (ITER-CN-PT) modeling and are the current focus in the world fusion was held in Beijing, May 15-19, 2006. The meeting