Effects of finite radial excursion on the slowing-down distribution of toroidally circulating energetic ions produced by tangential neutral beam injection

Abstract

Slowing-down of the toroidally circulating energetic ions produced by tangential neutral beam injection is described by the reduced drift kinetic equation, in terms of three constants of motion (the energy, the magnetic moment and the canonical toroidal momentum), to take into account the effects of finite radial excursion of guiding-centers of the energetic ions. An approximate analytical solution to the slowing-down equation is obtained to describe the equilibrium slowing-down distribution of the toroidally circulating energetic ions in the core region of a large-aspect-ratio tokamak, with the effects of finite radial excursion included.