Current Profile, MHD Activity and Transport Properties of Optimized Shear Plasmas in JET
High fusion performance has been achieved in optimized shear discharges in JET with early appearance of internal Transport Barriers in the high power phase in both DD and DT plasma. An ITB has been produced in a large variety of conditions, including Lower Hybrid Current Drive only, Ion Cyclotron Resonance Heating only, Neutral Beam Injection only and NBI+ICRH with LHCD preheat. An ITB may coexist with the edge barrier. High pressure gradient produced by ICRH combined with high power NBI heating starting in low density plasma with q(0)=1.5-2 is the main prerequisite of an efficient ITB in high performance discharges. Strong coupling between q profiles, MHD activity, energy confinement and fusion yield has been observed. Transition from L to H mode can be triggered by MHD events. The transition is accompanied by significant momentary changes in the density fluctuation spectrum in the peripheral plasma. The ITB may persist for some time in both ELM free and ELMy H-mode.
Bibliographic Reference: Article: JET-P(98)72
Record Number: 199910840 / Last updated on: 1999-06-11
Original language: en
Available languages: en