Operational limits for high edge density H-mode tokamak operation
Operational regime boundaries for High confinement mode (H-mode) plasmas with high edge density are investigated on the ASDEX Upgrade tokamak. In addition to the MHD stability boundary imposed by Edge Localized Modes (ELMs) and the H-mode threshold, the onset of complete divertor detachment limits the accessible separatrix density. At the H-mode density limit, a transport enhancement is observed that reduces the temperature gradient in the edge of the main plasma and can lead to a disruption by loss of H-mode and subsequent radiation and resistive MHD instability. This 'transport limit' occurs parallel to full divertor detachment at high edge collisionalities. A possible origin is drift-Alfven-balloning turbulence driven by the pressure gradient at high collisionallity.
Bibliographic Reference: Article: Journal of Nuclear Materials, 266-269, (1999), 118-123
Record Number: 199910715 / Last updated on: 1999-05-14
Original language: en
Available languages: en