Toroidal Plasma Current Startup and Sustainment by rf in the WT-2 Tokamak

By injecting the lower hybrid wave into the microwave discharge plasma at the electron-cyclotron resonance in the WT-2 toroidal device, the toroidal plasma current is generated, started up to ${I}_{p}\ensuremath{\simeq}5$ kA, and sustained by rf power alone, without the Ohmic heating power (rf tokamak). This lower-hybrid-wave-driven current is produced only when high-energy tail electrons, which interact resonantly with the lower hybrid wave, are present in the initial electron-cyclotron resonance plasma.