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Various steady-state non-inductive plasmas, with strong electron heating and significant modification of the current density profile, have been routinely obtained on Tore Supra in either lower hybrid current drive or fast wave electron heating experiments. In those dominant electron heating discharges, the dependence of electron heat diffusivity (chi(e)) on the electron temperature gradient, the magnetic shear (s) and the safety factor (q) has been investigated. The increase of chi(e) with electron temperature gradient indicates the existence of a critical temperature gradient. Moreover, the current density profile effect on the global confinement and the local transport is clearly observed. The electron heat flux (q(e) is found to be roughly proportional to q{2}. The effect of magnetic shear on chi(e) is studied in the improved confinement discharges obtained by modifying of the current profile. chi(e) decreases when the magnetic shear increases in the confinement zone and/or when it vanishes in the plasma center. When s becomes negative a decrease in chi(e) by two orders of magnitude is observed. The effect of the current profile is also observed in the saturated ohmic regime. Comparisons between experimental chi(e) and well known local transport models (Taroni, and Rebut-Lallia-Watkins) are reported.

Additional information

Authors: HOANG GT ET AL, CEA, CEN Cadarache, Saint-Paul-lez-Durance (FR);BUDNY RV, Princeton Plasma Physics Laboratory (US)
Bibliographic Reference: Article: CEN Cadarache Laboratory Report (1996) EUR-CEA-FC-1582
Record Number: 199611238 / Last updated on: 1996-11-11
Original language: en
Available languages: en
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