Experimental studies of electron cyclotron heating in a stellarator plasma have been carried out by injecting 40 kW of 35.5 GHz microwave power. Electron cyclotron heating 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 average electron density of 6 × 1012 cm−3. Efficient heating by the extraordinary mode in the presence of the cyclotron cut-off is interpreted to be achieved by the penetration of scattered waves from high- and low-field sides, polarization being disturbed by microwave reflection from the vacuum chamber wall.
Electron cyclotron wave propagation and absorption in the Compact Ignition Tokamak