Application of the gyrokinetic velocity moment theory in finite beta plasma

Abstract

The calculation of the velocity moment in the gyrokinetic theory is investigated in the finite beta plasma. According to the scalar invariance property in the Lie-transform method, the particle velocity in terms of the gyrocenter coordinates is derived, where the drift velocity driven by the second-order Hamiltonian is illustrated. The parallel component of particle velocity is found to be the same as that from the pull-back transformation of the parallel velocity variable v¯∥. The parallel and perpendicular velocity moments are systematically calculated according to the parallel and perpendicular components of particle velocity. The poloidal Reynolds stress (PRS) driven by the electromagnetic fluctuation is illustrated. By considering the magnetic drift resonance in the quasilinear analysis, the PRS contains two parts: one is related to the electrostatic fluctuation and the other is related to the parallel magnetic vector fluctuation; compared to the case with the electrostatic fluctuation, the PRS in the case with the electromagnetic fluctuation is enhanced by the electromagnetic effects, which may be beneficial for the enhancement of zonal flows and the reduction of turbulent transport.