Particle Simulation of the Neoclassical Plasmas

A 5D Monte Carlo particle simulation method for advancing rotating plasmas in tori is presented. The method exploits the neoclassical radial current balance (quasineutrality condition). Including the ion polarization current gives the time rate of change of the radial electric field and related evolution of the rotation velocity components. A special orbit initialization for a quiescent start and an efficient radial flux solving algorithm with reduced numerical noise are developed. Numerical stability of the method with respect to the strength of the perpendicular viscosity and Mach number of the poloidal rotation is investigated. This new approach enables one to separate the nonambipolar transport characteristics from the ambipolar ones. Because nonambipolar transport can support sheared flows, this model can provide a very efficient tool for studying transport barriers and related neoclassical mechanisms in toroidal plasmas.