Boltzmann-Fokker-Planck Kinetic Solver with Adaptive Mesh in Phase Space.

We describe the implementation of kinetic solvers in 1d2v phase space using adaptive Cartesian mesh. Spherical coordinates in velocity space are used to simplify the Lorentz and Fokker-Planck collisional operators. The key capabilities of the new solvers are illustrated for electron elastic scattering, acceleration, continuous energy loss in collisions, and ionization processes in weakly-ionized plasma. We have also implemented two-stream approach to reduce computational cost for studies of gas breakdown dynamics in the presence of runaway electrons. The benefits and limitations of the nonsplit- phase-space method for kinetic solvers with adaptive mesh in phase space are discussed. [ABSTRACT FROM AUTHOR]