Time Diffusion Method For Gyrokinetic Simulation Of Electrostatic Turbulence With Kinetic Electrons (Vol 269, 108114, 2021)

A new method based on a time diffusion technique is developed to mitigate the numerical instability induced by the high frequency electrostatic shear Alfven wave (omega(H) mode) in the gyrokinetic simulation of electrostatic turbulence. It can preserve fully drift-kinetic electron effects and can be incorporated efficiently with explicit time integration scheme. This method has been implemented in the semi-Lagrangian gyrokinetic code NLT (Lei Ye, et al. (2016) [25]) and applied successfully to linear and nonlinear ITG/TEM turbulence simulation. Numerical results show that this time diffusion method can greatly enlarge time step size and improve numerical stability for electrostatic turbulence simulation in tokamaks. (C) 2021 Elsevier B.V. All rights reserved.