Regime of improved confinement in neutral-beam<i>–</i>heated limiter discharges of a tokamak

Abstract

A new operational regime has been observed in neutral-beam--heated JFT-2M limiter discharges. This regime is characterized by confinement times close to those of Ohmic and divertor H-mode (good confinement mode) discharges. The properties of these discharges are similar to the divertor H mode. The incremental energy-confinement time due to the heating is found to be independent of the plasma density up to the maximum density.