H-mode studies on TUMAN-3 and TUMAN-3M

Abstract

The focus of the TUMAN-3 and TUMAN-3M tokamaks programme is on issues of improved confinement. The transition from an ordinary ohmic regime into improved confinement mode has been found in circular limiter configuration in a vessel with all-metallic walls and limiters. The signatures of the H-mode in auxiliary heated tokamaks have been observed in this regime. The crucial role of the radial electric field was found in experiments with internal probe biasing. Other techniques were demonstrated to trigger H-mode: short increase of the working gas puffing rate, minor radius magnetic compression and pellet injection.