Ev. Belova et al., HYBRID SIMULATIONS OF THE EFFECTS OF ENERGETIC PARTICLES ON LOW-FREQUENCY MHD WAVES, Journal of computational physics, 136(2), 1997, pp. 324-336
A hybrid MHD-gyrokinetic simulation model is presented which is suitab
le for self-consistent study of the interaction of energetic particles
with low-frequency MHD waves. Fully electromagnetic gyrokinetic equat
ions are used to describe the energetic particles, while the cold back
ground plasma is treated as a fluid, using nonlinear one-fluid MHD equ
ations. Based on this model a hybrid MHD-gyrokinetic particle code has
been developed. A delta f algorithm has been implemented in the code
for beta similar to 1 electromagnetic perturbations. The gyrokinetic d
escription enables us to remove the restriction on the particle time s
tep dictated by the gyromotion, while the delta f algorithm strongly r
educes the simulation numerical noise level. Therefore, considerably l
arger time steps and a smaller number of particles can be used in the
simulations as compared to conventional methods. The conservation prop
erties of the model and corresponding delta f scheme have been investi
gated. Representative two-dimensional simulations of the mirror instab
ility and the temperature gradient driven instability of the compressi
onal mode were performed, and the simulation results are in very good
agreement with linear theory. (C) 1997 Academic Press.