Observation of a Resistive Wall and Ferritic Wall Modes in a Line-tied, Screw Pinch Experiment

Full text: We report an overview of theoretical and experimental results from research on the Rotating Wall Experiment, a linear screw pinch experiment at the University of Wisconsin. The overall goal of the work is to test the hypothesis that moving metal walls can stabilize the resistive wall mode (RWM) in the simplified (relative to a torus) geometry of a cylinder where spinning, conducting walls can be used instead of flowing liquid metals. The resistive wall mode has been clearly identified in the experiment; thin, thick, and ferritic shells have been used and an external kink mode has been observed whose growth rate scales inversely with the shell time. A Mumetal shell (in addition to the thick copper shell) was shown to be destabilizing - the plasma is stable without the Mumetal and destabilized with it. Finally, clear evidence for magnetic reconnection is observed in two ways, (1) in the merging of seven individual current carrying columns into a single current channel, and (2) in discrete current relaxation events which periodically flatten the current profile. (author)