ICRH modulation on TEXTOR: Eigenfunctions of the quasilinear Fokker-Planck equation and experimental results

In order to analyze RF amplitude modulation experiments on TEXTOR, the authors have develop a realistic three-species model for the energy transfer during RF heating. They investigate the stationary and the nonstationary behaviour using the quasilinear isotropic Fokker-Planck equation with a global minority confinement time. An important result is that many characteristic times including small ones for the ions' slowing down contribute to the process. The average and the modulated power going to the minority ions are found to be differently distributed among species. They take into account the effect of the sawteeth and of the density modulation in the interpretation of the experimental data obtained on TEXTOR and we apply their model to the analysis of this corrected data. This analysis provides the distribution of power absorption through the minority and mode conversion mechanisms.