Particle versus density models for negative streamer fronts

Particle versus density models and hybrid computations for ionization fronts To understand ionization fronts and the growth of streamer channels, both density and particle models have been developed. The streamer channel consists of an ionized interior with many charged particles that is efficiently approximated by continuous particle densities, and a pulled ionization front where the statistics of few single particles can create velocity fluctuation and might trigger inherent instabilities. The goal of the project is therefore to develop a computation scheme that is hybrid in space. We explain concepts and implementations of the kinetic Monte Carlo model and of the spatially coupled one-dimensional hybrid model. We compare results for planar ionization fronts which have been carried out within the PDE model, the Monte Carlo model, and the hybrid model.