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5 most important scientific results over the 3 years: (not in order of importance). Physics of the current hole phenomena
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5 most important scientific results over the 3 years:(not in order of importance) Physics of the current hole phenomena B.C. Stratton, J.A. Breslau, R.V. Budny, et al, “The Role of axisymmetric Reconnection Events in JET Discharges with Extreme Shear Reversal”, Plasma Phys. Control. Fusion, 44,1127 (2002) J. A. Breslau, S. C. Jardin, and W. Park, “Simulation Studies of the Role of Reconnection in the “Current Hole” experiments in JET”, Phys. Plasmas, 10, 1665 (2003) W. Park, J. A. Breslau, J. Chen, et al, “Nonlinear Simulation Studies of Tokamaks and STs”, Nuclear Fusion, 43, 483 (2003) Suppression of the Richtmyer-Meshkov instability by a magnetic field R. Samtaney, “Suppression of the Richtmyer-Meshkov Instability in the Presence of a Magnetic Field”, Phys. Fluids, 15, L53-L56 (2003) Diamagnetic stabilization of MHD modes and enhanced reconnection in stellarators H. Strauss, G. Fu, W. Park, et al, “Nonlinear MHD and Energetic Particle Modes in Stellarators”, IAEA-CN-94/TH/P2-12 (19th IAEA Fusion Energy Conf. Lyon, France) L. E. Sugiyama, H. R. Strauss, W. Park, G.Y. Fu, et al, “Two-fluid limits on stellarator performance” Explanation of three stellarator puzzles and comparison to axisymmetric plasmas, “submitted to IAEA 2004 First-principles calculation of a tokamak thermal quench S. E. Kruger, D. D. Schnack, D. P. Brennan, T. A. Gianakon, and C. R. Sovinec, “Nonlinear MHD dynamics of tokamak plasmas on multiple time scales”, submitted to Nuclear Fusion E. D. Held, J. D. Callen, C. C. Hegna, et al, “Non-local closures for plasma fluid simulations”, Phys. Plasmas 11 2419 (2004) MHD and energy transport in SSPX R. H. Cohen, H. L. Berk, B. I. Cohen, et al, “Theoretical investigation of field-line quality in a driven spheromak”, Nuclear Fusion, 43, 1220 (2002) G. A. Cone and C.R. Sovinec, “Controlled ramp-down of decaying spheromak plasmas”, Bull. Am. Phys. Soc. 48, 152 (2003)
What is the role of Advanced Computing? • All of the projects in our center make use of advanced computing • The CEMM center used over 6,000,000 NERSC node-hours in FY2003 • mp288, mp21, mp94, mp290, m127, m275
What have we learned from the ISICs? • It has been confirmed that high order (3-5th) finite elements are a big win for fusion MHD: • a must for highly anisotropic heat conduction • leads to smaller matrices for same accuracy, making an implicit time advance feasible • Adaptive Mesh Refinement is a powerful tool for some transient problems with a range of space scales, • but it’s usefulness for slow-growing MHD modes has not been demonstrated. • It is valuable to have multiple, interoperable linear solvers available. • this is especially true now that the Cray-X1 is in the mix of architectures available to us
Is progress limited by computing power or by algorithms? • All of our new applications will be resource limited. • The resources available determine the allowed resolution, • This in turn determines what range of physical parameters can be realistically modeled. • However, our model extension activities require better algorithms.