Turbulent transport in collisionless plasmas: eddy mixing or wave-particle decorrelation? Z. Lin Y. Nishimura, I. Holod, W. L. Zhang, Y. Xiao, L. Chen University of California, Irvine, California 92697, USA P. H. Diamond University of California, San Diego, California 92093, USA T. S. Hahm, S. Ethier, G. Rewoldt PPPL, Princeton University, Princeton, New Jersey 08543, USA F. Zonca Associazione EURATOM-ENEA sulla Fusione, Frascati, Italy S. Klasky Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA Supported by US DOE SciDAC GPS Center
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Turbulent transport in collisionless plasmas: eddy mixing or wave-particle decorrelation? Z. Lin
Turbulent transport in collisionless plasmas: eddy mixing or wave-particle decorrelation? Z. Lin Y. Nishimura, I. Holod, W. L. Zhang, Y. Xiao, L. Chen University of California, Irvine, California 92697, USA P. H. Diamond University of California, San Diego, California 92093, USA - PowerPoint PPT Presentation
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Turbulent transport in collisionless plasmas: eddy mixing or wave-particle decorrelation?
Z. LinY. Nishimura, I. Holod, W. L. Zhang, Y. Xiao, L. ChenUniversity of California, Irvine, California 92697, USA
P. H. DiamondUniversity of California, San Diego, California 92093, USA
T. S. Hahm, S. Ethier, G. RewoldtPPPL, Princeton University, Princeton, New Jersey 08543, USA
F. ZoncaAssociazione EURATOM-ENEA sulla Fusione, Frascati, Italy
S. KlaskyOak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
Supported by US DOE SciDAC GPS Center
• ITG: isotropic eddies
• ETG: radial streamers
• Fluid picture: eddy mixing
• Kinetic process: wave-particle decorelation
Turbulence Structure & Transport in Tokamak
• To understand physical mechanism of electron heat transport in tokamak driven by driftwave turbulence Eddy mixing or wave-particle decorrelation? Resonant vs. non-resonant transport? Accuracy of mixing length estimate? Choice of time scales in transport models? Relation between instability drive, nonlinear saturation and
turbulent transport?
• Gyrokinetic particle simulation of microturbulence Systematic measurement of nonlinear spatial & temporal scales Quantitative test of quasilinear theory in tokamak geometry
Motivation: electron heat transport in tokamak
• Case studies of electron heat transport mechanism in tokamak
Comparative studies of CTEM, ITG, & ETG
• GTC simulations: while saturation can be understood in context of fluid processes, kinetic processes related to instability drive often responsible for transport
Transport: eddy mixing or wave-particle decorrelation?
Instability Electron temperature gradient (ETG)
Ion temperature gradient (ITG)
Collisionless trapped electron mode (CTEM)
Electron drive Parallel resonance Non-resonance Precessional resonance
Saturation Nonlinear toroidal coupling
Zonal flows Zonal flows
Electron heat Transport
Wave-particle decorrelation
Nonlinear mode scattering off trapped electron?
Processional resonance de-tuning? Avalanche?
GTC global gyrokinetic particle simulation
• GTC [Lin et al, Science1998] global field-aligned mesh: reduces computation by a/~100 Twisted across flux surfaces by magnetic shear # of spatial grids N~(a/)2
Respect physical periodicity Radial variations of equilibrium quantities
• Gyrokinetic particle-in-cell approach Efficient sampling of 5D phase space
• Massively parallel computing Resources made available by US SciDAC GTC selected for early applications of 250TF ORNL computer
• Object-oriented GTC for collaborative code development and for integrating kinetic electron, electromagnetic, multiple ion species, and MHD equilibrium
GTC nonlinear convergence in ETG simulation• Convergence from 400 to 2000 particles per cell