Abstract Details

Overview of Physics Advances in MST

Author: Darren Craig
Submitted: 2005-12-20 14:09:17

Co-authors: and MST Team

Contact Info:
University of Wisconsin - Madison
1150 University Ave.
Madison, WI   53706
USA

Abstract Text:
MST continues to be a fruitful device for plasma physics, particularly for studies of magnetic fluctuations and their effect on transport, the current profile, and ion heating. Multi-point Thomson scattering measurements of the electron temperature profile highlight the dramatic improvement in electron energy confinement during periods of reduced fluctuations with current profile control and the equally dramatic degradation of confinement during increased fluctuations at a sawtooth crash. In quasi-single helicity plasmas (where one magnetic mode dominates the spectrum) double filter SXR tomography has been used to infer temperature profiles and observe an enhancement of the temperature inside the dominant island. Hard X-Ray measurements also show evidence for generation of a confined high energy electron population when a large island is present. The current profile is strongly modified by both single and two-fluid effects arising from the magnetic fluctuations. Fast Charge Exchange Recombination Spectroscopy measurements of velocity fluctuations yield information on the MHD dynamo and fast FIR Faraday rotation measurements of current density fluctuations yield information on the Hall dynamo /en. Both are important in balancing Ohm’s law. The current density fluctuations also induce a significant non-ambipolar charge flux during reconnection events. Ion heating accompanies bursts of magnetic fluctuations and is measured to be a global effect, present at all radii during a sawtooth crash. Spatially non-uniform features can exist, however, when edge resonant modes burst during periods of improved confinement. Here, a more edge localized heating is measured. Magnetic fluctuations which grow in time cause magnetic reconnection in MST. Measurements have also been made of the origin of impulsive reconnection, particularly from m=0 modes, and the importance of multi-site reconnection for obtaining the strongest effects of fluctuations on the plasma.

This work is supported by U.S.D.O.E. and the N.S.F.

Characterization: E5,E6

Comments:
Group with other MST posters