Ray tracing study of the electron cyclotron current drive in DIII-D using 60 GHz

The efficiency of the electron-cyclotron current drive using 60-GHz sources in the DIII-D tokamak is numerically investigated for the following cases: The inside-launched fundamental extraordinary mode, the outside-launched fundamental ordinary mode, and the outside-launched second-harmonic extraordinary mode. In the limit-weak ECH power and for plasma parameters relevant for experiments, illumination of the plasma with inside-launched fundamental extraordinary mode is found to have the highest efficiency