Magnetic Surface Visualizations in the Columbia

Visualizations of magnetic surfaces are a valuable diagnostic in the Columbia Non-neutral Torus (CNT). CNT is a compact stellarator, which is currently being used to study non-neutral plasmas confined on magnetic surfaces. The full three-dimensional shapes of magnetic surfaces created by CNT's simple four circular coil geometry are readily visualized using an electron beam and neutral gas. These visualizations are useful for probe alignment, confirmation of the magnetic surface topology, and were necessary for the recent installation of a conducting boundary conforming to the last closed magnetic surface. Index Terms—non-neutral, stellarator, magnetic surfaces, vi- sualization