Observations and Models of Scrape-Off-Layer Current (SOLC) Dynamics During Edge Kink Instabilities in HBT-EP

Scrape-off-layer currents (SOLC) are detected in HBT-EP during kink instabilities, resonant magnetic perturbations (RMPs), and disruptions\footnote{Levesque, \textit{et al.}, \textit{Nuc Fusion}, \textbf{57}, 086035 (2017).} These currents are associated with helical ``filaments'' and ``bubbles'' at the plasma edge\footnote{Angelini, \textit{et al.}, \textit{Plasma Phys Contr Fusion}, \textbf{57}, 045008 (2015).} that become very large during disruptions. SOLC are correlated with the poloidal and toroidal structure of magnetic perturbations. The magnitude of SOLC increase with increasing magnetic perturbations; they can appear with constant amplitude and typically rotate in the electron drift direction. Like ELM filaments, 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.'' These SOLC are like large-sized versions of ELM filaments\footnote{Vianello, \textit{et al.}, \textit{Phys Rev Lett}, \textbf{106}, 125002 (2011).} and blobs. This motivates discussion of SOLC models used elsewhere to help on-going investigations of scrape-off layer (SOL) currents during kink instabilities and disruptions in HBT-EP.