Plasma Expansion from a Pulsed Power Electrode Surface

The status of measurements of plasma expansion from a current-carrying electrode surface in a pulsed power feed will be discussed. Experiments on COBRA at Cornell show slow expansion while current is rising, and rapid expansion coincident with driving voltage reversal and the beginning of current reduction. Interferometry of the expanding plasma density, visible light spectroscopy to give plasma temperature, and magnetic field measurements by Bdot probes and polarization Zeeman technique will be shown. The possible importance of inverse skin effects in driving the rapid expansion withvoltage reversal will be discussed.