Introduction of kinetic effects to fluid simulation by a particle model

Fluid simulations are mainly used for SOL/divertor plasma modeling, but there are some discrepancies between simulated and experimental results. It is thought that one of the reasons is that fluid simulations cannot sufficiently treat kinetic effects. Particularly, in edge plasma when collisionality is weak, the velocity distributions of electrons and ions are distorted from Maxwellian distribution, and kinetic effects become important. Then, in this study, we have tried to introduce kinetic effects to fluid simulation by combining with particle simulation. The particle simulation can correctly treat kinetic effects in the non-Maxwellian region, but it is difficult to apply the particle simulation to a large system and in a long time scale due to its high cost. In order to overcome this obstacle, we do not calculate the self-consistent electric field but just adopt the sheath boundary condition model. Plasma parameters obtained by a fluid simulation are converted into velocity distributions for electrons and ions, and these data are taken as initial values of particles. By calculating the trajectories considering collision for a short time scale, we have successfully introduced the particle simulation results, which correctly consider kinetic effects, into the fluid simulation.