Thirty-Minute Plasma Sustainment by ICRF, EC and NBI Heating in the Large Helical Device

Steady-state plasma heating was successfully performed and sustained for more than 30 min in the LHD. By using ICRF heating and additional EC and NBI heating, a total input energy of 1.3 GJ was achieved. The average input power was 680 kW and the plasma duration was 31 min 45 sec. The hardware of the ICRF and divertor plates was much improved and the position of the ICRF antenna was optimized. The heat load to the divertor plates was effectively dispersed by the magnetic axis swing technique, which caused large changes in the heat load distribution along the divertor leg traces.