ELECTRON CYCLOTRON HEATING OF STELLARATOR PLASMA WITH THE ORDINARY AND THE EXTRAORDINARY MODES IN JIPP T-II

Abstract

Experimental studies of electron cyclotron heating in stellarator plasma have been carried out by injecting 40 kW of 35.5-GHz microwave power. Electron cyclotron heatings with the ordinary and the extraordinary modes injected from the low field side show almost the same heating efficiency of 2.2 × 1013 eV-cm−3.kW-1 at the averaged electron density of 6 × 1012 cm-3. Efficient heating by the extraordinary mode in the presence of the cyclotron cutoff is interpreted to be achieved by the penetration of scattered waves from high and low field sides, because reflections of microwave at the vacuum chamber scramble the polarization and scatter the microwave power around the torus.