April 15-17

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Author: HONGYU WANG
Requested Type: Poster
Submitted: 2019-02-22 13:24:12

Co-authors: I. Holod, Z. Lin, J. Bao, L. Shi, S. Taimourzadeh

Contact Info:
UCI
4172 Frederick Reines Hall Irv
Irvine, California   92697
United States

Abstract Text:
We report gyrokinetic particle simulation of ion temperature gradient (ITG) turbulence in Wendelstein7-X (W7-X) and Large Helical Device (LHD) stellarators by using Gyrokinetic Toroidal Code (GTC). Linear simulations of ITG instabilities are first carried out in partial torus by taking advantage of the toroidal periodicity of stellarators. The turbulence mesh in parallel direction and equilibrium mesh in toroidal direction are separated in simulations of stellarators in GTC, and growth rate and frequency convergence are achieved for those two kinds of meshes. The 2D spectra, toroidal and poloidal spectra have been studied to investigate the dominant mode and unstable mode range in stellarators. Electrostatic potential is presented in 3D space, on flux surface, and on poloidal plane. The mode structure in W7-X is localized in the toroidal direction, while in LHD it is more extended in the toroidal direction and tokamak-like. The verification of linear simulations of ITG of both LHD and W7-X have been done using GTC and EUTERPE, and good agreement are achieved in growth rates, frequencies, spectra, and mode structures. Initial nonlinear simulation results of ITG instability saturation and thermal ion transport in stellarators, as well as comparisons between turbulent and neoclassical transport in W7-X will be presented.

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