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Abstract

Formation of core regions in Tore Supra and JET tokamaks with reduced transport coefficents is reported. Characteristics of the enhanced confinement regions and the physics process involved in their formation and maintenance should be considered seperately when the electron or ion components are predominately heated.

In Tore Supra and JET, central electron temperature transitions are observed by injecting lower hybrid waves at modest power levels during the current ramp-up phase of the discharges. Transport analyses stress the importance of the low magnetic shear in the core to explain the anomalous electron transport reduction.

With high-power dominant ion heating schemes in JET (neutral beam injection and ion cyclotron resonance heating), internal transport barriers have been obtained in plasmas fuelled with a mixture of deuterium-tritium ions leading to a successful production of fusion power in this regime. Similar additional power levels to those applied in pure deuterium plasmas are required to establish internal transport barriers in D-T plasmas. In D-D and D-T plasmas, ion thermal diffusivities are reduced close to their neoclassical levels in the plasma core and electron thermal diffusivities decrease by one order of magnitude at midplasma radius. The combined role of magnetic shear and E x B velocity shear can explain the formation and evolution of plasma core regions with low energy transport coefficents. ts.

Additional information

Authors: JET JOINT UNDERTAKING, ;ABINGDON (GB), ;CEA CADARACHE (FR), ;CHALMERS UNIVERSITY OF TECHNOLOGY, ;GOTHENBURG (SE), ;HELSINKI UNIVERSITY OF TECHNOLOGY (FI), ;UNIVERSITE DE PROVENCE, ;MARSEILLE (FR),
Bibliographic Reference: Article: Plasma Physics and Controlled Fusion, 41(1999), 733-746
Record Number: 199910751 / Last updated on: 1999-05-21
Category: PUBLICATION
Original language: en
Available languages: en