Recent Results in Diagnosis of Magnetic Field Distribution in Gas-Puff Z-Pinches Using a Faraday Rotation Diagnostic

Gas-puff Z-pinch implosions are magnetically driven implosions of an annular plasma sheath which is compressed onto the Z-axis. Understanding the distribution of current which generates this driving magnetic field in the imploding plasma sheath is key to understanding its dynamics. Here we present progress in measuring the magnetic field distribution in the imploding plasma using a Faraday Rotation magnetic field diagnostic, from which the current distribution can be calculated. The gas-puff Z-pinches under study are generated on the 1-MA COBRA generator at Cornell University using a triple gas puff nozzle, where outer and inner annular plasma sheaths collapse onto a central target jet, compressing it. These plasmas are generated with current rise times from 100-200ns, with variable gas species and pressures. The Faraday Rotation measurements are supplemented with gated visible-UV light self-emission images, XUV (extreme ultraviolet) quadrant images, PCD (photo-conducting diodes) signals, and interferometry measurements to diagnose the implosion dynamics and the electron density. These diagnostics are combined to calculate the magnetic field distribution during the implosion with high spatial and temporal resolution.