Vlasov-Fokker-Planck plasma simulation using the BLOB technique

Summary form only given, as follows. Particle-in-cell (PIC) methods are well-assessed tools in Vlasov plasma simulation. The model can be generalized to include collisions by employing Monte-Carlo techniques for simulating close interactions. This introduces extra numerical noise due to the random numbers used in modeling collisions. Recently, the BLOB technique has been introduced as a generalization of PIC modeling. The method employs particles having variable shape in phase-space. Each particle is associated with a shape function, depending on a number of parameters (in 1D simulations, x variance, v variance, and x-v cross correlation is a physically consistent choice). Due to its ability in describing the phase-space distribution better than PIC codes, the BLOB technique allows one to reduce greatly the number of computational particles. In the present work, the method is generalized in an easy and natural way to include Fokker-Planck collisions by simply adding a suitable term to the equation governing the evolution of the velocity variance. This term introduces a broadening in the velocity width of each particle in a fully deterministic way. Numerical tests show the effectiveness of the proposed technique in terms of noise reduction and computational effort.