Pump limiter experiment on the JFT-2M tokamak

Abstract A pump limiter is applied to the JFT-2M tokamak in order to reduce edge gas buildup. About 12% of the effective loss flux is removed by the pump limiter and the fueling efficiency is improved by 30%. In the high density regime, the gas buildup is successfully reduced and edge cooling by cold gas-puffing is prevented by the pump limiter. The pump limiter also improves the density limit and the energy confinement time. Improvement in the nτ value is about 34%. This pump limiter is shown to be compatible with the limiter H-mode.