Preliminary thermal analyses of the beamline components in JT-60SA neutral beam injection system

Komata, Masao; Mogaki, Kazuhiko; Kazawa, Minoru; Hanada, Masaya; Ikeda, Yoshitaka

In JT-60 Super Advanced (JT-60 SA) where the first plasma will be in 2014, D beams of 10 MW are designed to be injected for 100 s. The negative-ion-based neutral beam injection (N-NBI) system in JT-60U will be upgraded from existing JT-60U N-NBI system while the modification of existing components should be minimized. The feasibility on the further long pulse operation of the existing beamline components in the JT-60U N-NBI system, which has successfully injected 3.2 MW for 21 s, has been studied. The thermal characteristic of the beamline components during long pulse operation was estimated by a three-dimension analysis code (AMPS). As the result, it is found that most of the beamline components except for the 4th beam limiter without water cooling and a plasma grid and acceleration grids in the negative ion source are to be available without modification in the JT-60 SA N-NBI system. For the 4th beam limiter, the water cooling is required to withstand the power loading. For the acceleration grids, the power loading of the grounded grid should be reduced to a half of the present value to realize a 10 MW injection for 100 s.