Modelling of ICRH slow wave propagation and absorption in Wendelstein 7-X stellarator

Abstract

The propagation and absorption of the slow waves (SWs) in the three-ion plasma of the Wendelstein 7-X stellarator have been investigated by ray tracing. The aim of the study is to obtain a qualitative notion of the penetration into the plasma and absorption of the wave excited by the potential difference between the antenna conductors and the antenna box. It has been discovered that the rays propagate along the magnetic field lines over a significant distance, up to 6 m, from the antenna. They weakly, to a depth of 0.1 m, penetrate into the plasma. Absorption of the SWs by electrons does not lead to the generation of the currents capable of affecting the plasma equilibrium. Most of the SWs are absorbed beyond the region of ion–ion hybrid resonance in the zone of cyclotron resonance of ^3 He ions at the periphery of the plasma. The ICRH of the three-ion W 7-X plasma will be used to heat ^3 He ions to high energies and simulate the confinement of alpha particles in an optimized stellarator configuration. The presence of a source of hot ^3 He ions, which are poorly confined, at the periphery of the plasma can affect the experimental results.

Keywords

• ICRF heating
• Wendelstein 7-X
• three-ion plasma
• slow wave