Energetic particle distribution in a toroidal plasma with neutral injection heating

The energetic ion distribution resulting from the injection of high-energy neutrals into a toroidal plasma has been derived. An appropriate kinetic equation which contains the angular scattering, friction, and diffusion of the energetic ions by the background particles, charge exchange on the background neutrals, and acceleration of the ions by the electric field has been solved analytically by use of the WKBJ method. Collisions of the energetic ions with the faster moving electrons results in some of the ions increasing their energy above the injection energy. The width of this ``high-energy tail'' is shown to depend upon the electron temperature and the electric field. An estimate of the effect upon the width of this tail of collisions between the energetic ions themselves is also given. Finally, illustrated examples of the various significant physical processes are presented.