Two-dimensional time-dependent solution of Stix's equation for the distribution function of minority ions during ion cyclotron resonant heating
The flux-surface-averaged Fokker-Planck equation for the distribution of minority ions during Ion Cyclotron Resonant Heating (ICRH) introduced by Stix in a classic paper is solved keeping two dimensions in velocity space (speed and pitch-angle) plus time. An approximation to the distribution function f is developed by means of an expansion in Legendre polynomials of the pitch-angle, and its convergence is studied both by successively increasing the number of retained terms and by comparison with the solution obtained solving the equation numerically on a two-dimensional grid. A steady-state is achieved typically within three Spitzer slowing-down times. A good approximation to the pitch-angle average of f is obtained already with two terms kept in the expansion, for a wide range of heating parameters including the ones typical of the Joint European Torus (JET).
Bibliographic Reference: Report: JET-P(96)56 EN (1996) 18pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (GB)
Record Number: 199710054 / Last updated on: 1997-02-26
Original language: en
Available languages: en