1999 Volume 75 Issue 2 Pages 131-142
A new gyrokinetic particle simulation method using the orbit averaged electron drift-kinetic equation has been developed in a three dimensional slab geometry. Using the large discrepancy between the time scale of the low frequency fluctuations and the Courant-Friedlichs-Lewy condition determined by the electron ballistic mode, the transit time ordering, ω/ωtrθ(ε), is introduced. The motion of the high energy transit electron is averaged over the periodic unperturbed orbit by means of the action-variational Lie perturbation method. In a new gyrokinetic Vlasov-Maxwell system, the drift-kinetic equation for the high energy part of the electron distribution function reduces to a two dimensional problem, which involves only the E×B nonlinearity, and the adiabatic response to the low frequency fluctuation is renormalized in the field equation. The ballistic mode arising from the high energy transit electron is removed and a longer simulation time step is enabled.