Observations of the Moving Plasma Edge during Magnetic Perturbations and Instabilities in HBT-EP

Magnetic perturbations move the boundary of toroidally-confined plasma, which can be detected by local probes, optical videography\footnote{Angelini, \textit{et al.}, \textit{Plasma Phys Contr Fusion}, \textbf{57}, 045008 (2015).}, x-ray emmision, and scrape-off-layer currents (SOLC)\footnote{Levesque, \textit{et al.}, \textit{Nuc Fusion}, \textbf{57}, 086035 (2017).}. This poster summarizes these observations in the HBT-EP device caused by kink and tearing instabilities, resonant magnetic perturbations (RMPs), and disruptions. Particular attention is given to the physical structure of the helical ``filaments'' and ``bubbles'' associated with time-varying magnetic perturbations and the relationship of these structures to the strength and orientation of the magnetic perturbation. A linear relationship appears between the plasma's $n = 1$ helical displacement and the current flowing into the surrounding chamber$^3$, and these currents and plasma edge motion becomes very large during disruptions. As observed elsewhere, the SOLC in HBT-EP are primarily co-aligned with the plasma current and exhibit temporal distortion, consistent with an elevated electron temperature within the ``filament.'' This motivates calculations of the 3D magnetic field-line structure and comparison of this