Quiet direct simulation of Coulomb collisions

Quiet direct simulation Monte Carlo (QDSMC) is a new particle simulation technique that is applicable to a broad range of applications where the underlying system dynamics obey Fokker Planck equations. These include hydrodynamics, radiation transport, magnetohydrodynamics, diffusion, and collisional kinetic plasmas. At the beginning of each time step in QDSMC, the weights and abscissas of Gaussian-Hermite quadrature are used to deterministically create particles to sample the random process. At the end of the time step, particles are gathered to the computational mesh to obtain updated distributions of conserved quantities on the mesh and then the particles are destroyed. The creation and destruction of particles allows arbitrary dynamical range to be accessed quiescently with only a small number of particles per computational cell. The application of QDSMC to the simulation of Coulomb collisions is considered in this report, and the method is demonstrated on problems involving the collisional relaxation of non-Maxwellian distributions.