Boundary-induced effect on the spoke-like activity in E × B plasma
Abstract
The spoke instability in an E × B Penning discharge is shown to be strongly affected by the boundary that is perpendicular to B field lines. The instability is the strongest when bounded by dielectric walls. With a conducting wall, biased to collect electron current from the plasma, the spoke becomes faster, less coherent, and localized closer to the axis. The corresponding anomalous cross-field transport is assessed via simultaneous time-resolved measurements of plasma potential and density. This shows a dominant large-scale E × B anomalous character of the electron cross-field current for dielectric walls reaching 40%–100% of the discharge current, with an effective Hall parameter βeff ∼ 10. The anomalous current is greatly reduced with the conducting boundary (characterized by βeff ∼ 102). These experimental measurements are shown to be qualitatively consistent with the decrease in the E field that triggers the collisionless Simon-Hoh instability.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 01, 2019
- Source ID
- 10.1063/1.5092702
Entities
People
- A. I. Smolyakov
- A. Powis
- Eduardo Rodríguez
- Igor Kaganovich
- Valentin Skoutnev
- Yevgeny Raitses
Organizations
- Air Force Office of Scientific Research
- Princeton Plasma Physics Laboratory