An alternative method for calculating the RF plasma dielectric response in ICRH simulations

A new procedure for computing the plasma dielectric response in the ion-cyclotron range of frequencies (ICRF) is proposed. It is based on a coordinate system in which the parallel component of the wave-vector k _∥(m,n) of each wave mode is constant on magnetic surfaces. This representation allows drastic simplifications in the evaluation of the plasma dielectric response, and is very attractive both analytically and numerically. In the case of Maxwellian plasma distributions, the computations are significantly faster than in standard coordinates whereas for non-Maxwellian plasmas, further analytical developments become possible. We illustrate the new approach by simulating IC minority heating with the CYRANO full-wave code in the case of Maxwellian particle distributions. The results obtained with constant-k _∥ coordinates are benchmarked against the standard coordinates results, and speed and performance comparisons are presented. Besides performing substantially faster than the standard coordinates, the new coordinates allow the easy tabulation of the plasma dielectric response at the beginning of the computations and its subsequent interpolation according to the k _∥(m,n) spectrum required by each toroidal mode (n) in 3D simulations.