Current advance method and cyclic leapfrog for 2D multispecies hybrid plasma simulations (Q1323802)

The procedure introduced and described here is a new algorithm for hybrid plasma simulations. Its physical basis is the hybrid plasma model where ions are massive particles, but the electrons are represented by a massless fluid. In contrast with previous methods, this one is distinguished by four features: (1) it is capable of treating multiple ion species -- with only one pass through the particle data tables; (2) it advances the ionic current density, whereas the moment method advances fluid velocity; (3) it collects ``free streaming'' currents, and by this it avoids the treatment of the advective and ionic stress tensor terms in the moment method; (4) it is an application of the modified midpoint method to magnetic field evolution. The procedure is tested whether it models physics acceptably or not. The tests show e.g. that a quiet plasma remains quiet and stable with the energy conserved to within 5\% over about hundred gyrotime of ions. The MHD waves propagate at the correct speeds in the non-dispersive limit. Ion beams show a known instability, fast MHD pulse shows the importance of a care of the choice of cell sizes to avoid distortion of physics.