A gyrokinetic ion zero electron inertia fluid electron model for turbulence simulations

This paper describes the formulation of a hybrid model with fully gyrokinetic ions and a zero-inertia fluid model for the electrons. The electron fluid equations are derived from moments of the drift kinetic equation, taking the small mass ratio limit, but with finite electron temperature. This model eliminates the inertial Alfven wave and any physics relating to electron transit motion, making it useful for studying low frequency, high beta (beta much greater thanm(e)/m(i)) electromagnetic turbulence as well as kinetic magnetohydradynamics (MHD) physics including kinetic ballooning and toroidal Alfven eigenmodes. Electromagnetic effects (deltaB(perpendicular to)) are included through the parallel ion and electron current. A predictor-corrector scheme for the fluid part that is consistent with the gyrokinetic ion part has been developed. Here we derive the model equations, derive the linear kinetic-fluid theory in a three-dimensional shearless slab, and compare the simulation results with the linear theory. (C) 2001 American Institute of Physics.