Effect of pitch angle scattering on the distribution function of fast fusion products in a tokamak plasma

The results of a three dimensional (3-D) (in constants of motion space) Fokker-Planck simulation of the steady state collisional behaviour of fusion alphas in an axisymmetric TFTR-like tokamak plasma are presented. The distribution function of confined fusion products is shown to be strongly anisotropic and non-uniform in the radial co-ordinate. The influence of pitch angle scattering on distribution function anisotropy is investigated. It is shown that the distribution function of fast ions in the range where the cosine of the pitch angle is small is strongly influenced by this scattering. A qualitative comparison of numerical results and predictions of alpha particle distributions from previous studies is presented. (author). 21 refs, 5 figs