A δ f particle method for gyrokinetic simulations with kinetic electrons and electromagnetic perturbations

A δf particle simulation method is developed for solving the gyrokinetic-Maxwell system of equations that describes turbulence and anomalous transport in toroidally confined plasmas. A generalized split-weight scheme is used to overcome the constraint on the time step due to fast parallel motion of the electrons. The inaccuracy problem at high plasma β is solved by using the same marker particle distribution as is used for δf to evaluate the βmi/meA|| term in Ampere's equation, which is solved iteratively. The algorithm is implemented in three-dimensional toroidal geometry using field-line-following coordinates. Also discussed is the implementation of electron-ion collisional effects which are important when kinetic electron physics is included. Linear benchmarks in toroidal geometry are presented for moderate β, that is, β ≪ 1, but βmi/mc ≫ 1. Nonlinear simulation results with moderate β are also presented.

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