Toroidicity effects on the absorption of IC waves by electrons

Abstract

The poloidal modulation of the parallel velocity of charged particles in the tokamak magnetic field modifies the strength of electron absorption of the compressional wave in the Ion Cyclotron (IC) range of frequencies. We have developed a model of this effect which is sufficiently simple to be numerically tractable, and we have implemented it in the TORIC full-wave code, which solves the wave equation in toroidal axisymmetric geometry. We find that the effect is normally negligible in present-day devices, but its importance increases with the dimensions and the temperature of the plasma, and should be taken into account when estimating the competition between electron and ion heating and the efficiency of current drive in future reactor-grade plasmas.

An alternative method to mimic mode conversion for ion cyclotron resonance heating

“…In order to effectively solve the full-wave equation in hot plasmas, Fourier decomposition of the wave fields is necessary. For example, the TORIC code employs spectral representation of the wave fields in the poloidal and toroidal directions while applying the finite element method (FEM) in the radial direction [10][11][12][13]. The AORSA code applies the Fourier collocation method in three directions (horizontal, vertical and toroidal) [14].…”