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Abstract

A strong ITB was sustained in a reversed shear discharge in JET during a long time interval after a significant reduction in plasma heating power. The observed ITB evolution is reminiscent of the effect of hysteresis, associated in theory with turbulence suppression due to shear of the plasma rotation. The mechanism of ITB sustainment was analysed. Modelling of the plasma heating and current profile was done using the TRANSP and JETTO transport codes. The resulting q-profile evolution was verified by comparison with the pitch angle delta = B(p)/B(t) deduced from motional Stark effect measurements (where B(p) and B(t) are the poloidal and toroidal magnetic field, respectively). Turbulence stability was analysed using the gyro-kinetic code Kinezero. It was shown that the strong negative magnetic shear produced by LHCD and sustained mainly by the bootstrap current in the plasma core is responsible for the turbulence stabilization. Stabilization due to shear of the plasma rotation and finite beta-stabilization play a complimentary role. The effect of bootstrap and LH driven currents on magnetic shear in JET discharges was analysed.

Additional information

Authors: BARANOV YU F, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);CHALLIS C D, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);GIROUD C, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);HAWKES N C, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);BOURDELLE C, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);JOFFRIN E, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);BOLZONELLA T, Associazione Euratom-ENEA sulla Fusione, Centro.Richerche Energia ENEA-Frascati, Frascati (IT);PERICOLI RIDOLFINI V, Associazione Euratom-ENEA sulla Fusione, Centro.Richerche Energia ENEA-Frascati, Frascati (IT);DE BAAR M, FOM Instituut voor Plasmafyisica Rijnhuizen, Euratom-FOM Association, Trilateral Euregio Cluster, Nieuwegein (NL)
Bibliographic Reference: An article published in: Plasma Physics and Controlled Fusion 47(2005), pp. 975-993
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://dx.doi.org/10.1088/0741-3335/47/7/002
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