Collisional Effects on Drift Wave Microturbulence in Tokamak Plasmas
Wei Hu1,2,3**, Hong-Ying Feng4, Chao Dong2,3
1Department of Modern Physics, University of Science and Technology of China, Hefei 230026 2Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 3University of Chinese Academy of Sciences, Beijing 100049 4College of Mechanical and Power Engineering, China Three Gorges University, Yichang 443002
Abstract：Collisional effects on the microturbulence, excited by the electrostatic drift-wave instability, are investigated through first-principle large scale gyrokinetic particle simulations using the realistic discharge parameters of the DIII–D Tokamak. In the linear simulations, the growth rates of the drift waves are decreased by the collisions compared to the collisionless simulations in the lower and higher $T_{\rm e}$ plasmas. In the lower $T_{\rm e}$ plasma, the collisions can promote the transition of the drift wave regime from the TEM-dominant instability to the ITG-dominant instability. The zonal flows are excited by the microturbulence and work as a modulation mechanism for the microturbulence in the nonlinear simulations. Microturbulence can excite high frequency zonal flows in the collisionless plasmas, which is in agreement with the theoretical work. In the lower $T_{\rm e}$ plasma, the collisions decrease the microturbulence in the nonlinear saturated stage compared to the collisionless simulations, which are beneficial for the plasma confinement. In the higher $T_{\rm e}$ plasma, the final saturated microturbulence shows a slight change.
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2018, Vol. 35 
