Kinetic modelling of the ECRH power deposition in W7-AS

Abstract

Kinetic effects are important in low-density high-power ECRH discharges, and the electron distribution function can significantly deviate from Maxwellian. The ECRH power deposition is analysed for perpendicular on-axis heating in W7-AS, with different magnetic configurations characterized by either a minimum or a maximum of B on the plasma axis in the RF injection plane. The different heating scenarios are modelled by means of a new bounce-averaged Fokker - Planck code, well suited for the magnetic field geometry close to the plasma axis of W7-AS.