JT-60 operation results after its modification for higher plasma current with single null open divertor

The hardware performance of the JT-60U (JAERI Tokamak-60 Upgrade) tokamak machine was investigated in several aspects. The experimental operation has advanced to record D-D fusion power as high as 17 kW. The displacement of the toroidal field coil was measured, and the effect of reinforcement was confirmed. The dynamic displacement of the vessel was found to be a vibration with amplitude within 0.3 mm and relatively slow dumping. Regarding the first wall, the divertor suffered from the heat flow with the width of 4 to 5 cm that was close to the design value. The divertor armor was found to rise 500 degrees C at most for the neutral-beam heating of 20 MW for 2 s, and it is still operated with nitrogen gas circulation cooling. The power flow to the divertor is low due to large radiations of the main and divertor plasmas, while the purity of plasma was largely improved by introduction of glow discharge cleaning of 300 V*1 A.<
>