Role of magnetic shear and ExB flow shearing rate in JET ITB discharges
Abstract
A database of plasma discharges has been selected in different experimental conditions (with and without an ITB; with positive or negative magnetic shear), to study the role of the magnetic shear and of the shearing rate. In most of the discharges ion and electron temperature profiles exibit identical features concerning the location and the timing of the transport barrier, but sometime the barrier occurs on electrons only. By taking into account the "correct" dependence of the magnetic shear in the linear growth rate evaluation, it is qualitatively possible to explain the radial location, the time of formation and the time evolution of different kinds of transport barriers in terms of the accepted mechanism based on the ExB shear flow suppression of ITG-driven turbulence. This is true for almost all the discharges of the selected database; however in some discharge the picture is not completely clear, either due to experimental errors or to the presence of an additional/alternative mechanism of turbulence suppression. The point will be discussed.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- October 2001
- Bibcode:
- 2001APS..DPPGP1042C