Global Mode Structure of Curvature and Rotation Driven Interchange
Abstract
A study of global mode structures of interchange modes driven by pressure and centrifugal forces created in a laboratory magnetic dipole is presented. Measurements and comparisons of radial, azimuthal and field-aligned mode structures are of interest. The mode structures are determined using a correlation analysis of movable floating potential probes located at various positions within the plasma. Hot electron interchange (HEI) instabilities are driven by a population of energetic, deeply trapped particles with a steep outward pressure profile produced by ECRH. Centrifugally driven Rayleigh Taylor instabilities are excited by the creation of radial electric fields which cause bulk azimuthal plasma ExB rotation. Electric fields are created with an equatorial hot-filament bias control system which alters the plasmas electrostatic potential by biasing inner flux tubes with respect to the outer chamber wall. The tungsten filament array enables axisymmetric as well as nonaxisymmetric radial fields and plasma convection. In addition, a new diagnostic 96-point gridded energy analyzer has been installed which diagnoses polar particle flux and is able to reconstruct 'movies' of the plasma flows. Finally, a self-consistent numerical simulation offers comparison with experimental observations of mode structure, plasma flows and instability growth and saturation.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..DPPGP1165L