Edge current profile measurements of peeling-like modes at high $\left \langle j_{edge} \bigl/ B \right \rangle$ in {\sc Pegasus}

Large-scale, coherent, high-$m$ filamentary edge instabilities are routinely observed under conditions of high $\left \langle j_{edge}\bigl/B\right \rangle$ in {\sc Pegasus}. These ELM-like filaments are characterized with high-speed imaging, as well as scanning magnetic and Langmuir probes. Their properties include: low- to intermediate-$n$; a coherent electromagnetic signature; large poloidal coherence lengths; rotation with the bulk plasma; and explosive detachment from the edge with outboard radial propagation. Stability is sensitive to $j_{edge}$, with mode drive or suppression dependent on the sign of $\dot{I}_{p}$. The extremely low $\mathbf{B}$ $\left(B_{t,0}\leq0.1\mbox{ T}\right)$ and high $ j_{edge} \approx 0.1 \mbox{ MA/m}^2$ in {\sc Pegasus} lead to high peeling instability drive, proportional to $\left \langle j_{edge}/ B\right \rangle$, comparable to that achieved in H-mode on larger experiments. However, in {\sc Pegasus} $j_{edge}$ is driven by large $\dot{I}_{p}$ ($\leq$ 50 MA/s) and associated skin currents as opposed to a localized region of high bootstrap current in an H-mode pedestal. A new radial array of Hall-effect sensors measures internal $B_{\theta,edge}(R)$ directly with high spatial and temporal resolution to provide strong experimental constraint on $j_{edge}(\psi)$ in equilibrium reconstructions. Such equilibria may be used to uniquely test predictions of peeling-ballooning stability theory.