Time-implicit simulation of particle-fluid systems

This paper presents one-dimensional particle-fluid hybrid simulations in which the strongly collisional components of the plasma (e.g., ions and thermal electrons with ν_cfΔt > 1) are treated as fluids and the weakly collisional components (e.g., energetic electrons with ν_cpΔt ≪ 1) are treated as particles. Here ν_cf denotes the fluid ion and electron collision frequencies, ν_cp is the energetic particle collision frequency and Δt is the time step. Collisions between particle and fluid components are treated by a Monte-Carlo method and mass transfers between the particle and fluid electron components are governed by collision frequency thresholds. The field is computed implicitly to allow time steps with Ω_p Δt > 1 (Ω_p: plasma frequency).