PARTICLE-FLUID HYBRID SIMULATIONS FOR WEAK BEAM-PLASMA INTERACTIONS

A particle simulation usually suffers from a high level of unphysical noise unless a large number of particles are used. To improve this situation, a hybrid scheme is used, replacing the general particle mover by a linearized fluid mover for those species of ions and electrons which do not undergo large amplitude perturbations and keeping the fully nonlinear particle mover for those species which experience more violent changes. The structures of these hybrid codes (electrostatic and electromagnetic) are shown with applications, which produce excellent agreement with linear and nonlinear theories plus substantial reduction in the noise level and the computing cost.