Bounce averaged Fokker–Planck theory of non-Maxwellian tail particles

Abstract

To take into account highly non‐Maxwellian tail distributions expected in fusion and/or auxiliary heated plasmas, a self‐consistent scheme of separating the non‐Maxwellian tail particles from the Maxwellian bulk in the quasilinear Fokker–Planck equation is proposed. The resulting equation for tail particles is the same as that for a minority species, but with a different boundary condition at low energies. Transport fluxes of energetic particles can then be calculated as a minority species that can be easily added onto existing transporttheory for the bulk species. Expressions for neoclassical fluxes of tail particles in the banana regime are obtained in terms of the solution of a steady‐state minority tail distribution which takes the place of the Maxwell distribution of a bulk species. The existence of a solution is demonstrated, and simple model analytic solutions are given.