The Influence of Trapping Effects on the Fusion Reactivity in NBI Heated Tokamak Plasmas
Fast computer codes for evaluating non-thermal velocity distributions are needed in order to carry out routine analysis of neutron signals in plasmas heated by neutral beam injection (NBI). By neglecting the magnetic field inhomogeneity along a field line (ie neglecting trapped particle effects), calculations of the velocity distribution can be made relatively fast. In this comment, we investigate under which circumstances such an approximation is justified. We solve the bounce-averaged Fokker-Planck equation, which includes particle trapping, by expressing the solution in terms of a series of appropriate eigenfunctions of the pitch-angle scattering operator. The eigenfunctions, eigenvalues and time-dependent coefficient functions are calculated numerically. We use the solution for calculating the effect of particle trapping on the fusion reactivity.
Bibliographic Reference: Report: JET-P(95)71 EN (1995) 8pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (GB)
Record Number: 199610509 / Last updated on: 1996-05-13
Original language: en
Available languages: en