Neoclassical transport of isotropic fast ions

Abstract

A study of radial gradient-driven neoclassical transport of fast ions, produced by an isotropic source in an axisymmetric toroidal system, is presented. The governing equation is a flux surface averaged Fokker–Planck equation that retains both the effects of the pitch angle scattering and drag. It is solved by utilizing an eigenfunction technique in conjunction with a rigorous numerical treatment. The results, which are valid for finite inverse-aspect-ratio ε, are found to fall between the previous limiting calculations [Nucl. Fusion 15, 359 (1975); Phys. Rev. Lett. 60, 1954 (1988)] for most of the relevant parameter regimes.