Ion cyclotron resonance frequency heating of deuterium plasmas in the Joint European Torus: Modeling of the resonant minority ion distribution function

Experiments were carried out in JET, the Joint European Torus [J. Wesson, Tokamaks (Clarendon, Oxford, 1997), pp. 581–603], to heat deuterium plasmas using ion cyclotron resonance frequency (ICRF) heating at fundamental hydrogen and second harmonic deuterium frequencies. These plasmas contained two minority resonant ion species, protons, and nonthermal deuterons due to neutral beam injection (NBI). To determine the resonant ion energy distribution functions in such plasmas, an iterative method for solving the hot-plasma dispersion relation was developed using a complex perpendicular wave number in cylindrical geometry. The distribution function of ICRF-heated ions is strongly anisotropic and significantly hotter than that of nonresonating particles. Therefore thermal and overlapping cyclotron harmonics effects were considered in computing wave dispersion and absorption. The formal solution of the lowest-order Fokker–Planck equation is derived for the slowing-down NBI deuterons. In a companion paper these results are applied to interpretation of measurements of distribution functions of ICRF-heated ions in the JET.