Selective Electron-Cyclotron Heating at Down-Shifted Frequency in the Lower-Hybrid-Current-Driven Plasma on the JFT-2M Tokamak

It is observed that the extraordinary mode near the second harmonic effectively couples to electrons at largely down-shifted frequencies. From measurements of soft-x-ray radiation and third-harmonic electron-cyclotron emission, selective heating of electrons with an energy satisfying the relativistic cyclotron resonance condition is deduced. It is demonstrated that the selective electron-cyclotron heating of 70 kW produces a 65-kA/sec rampup of the lower-hybrid-driven plasma current.