Experimental Post-Hole Convolute Plasma Studies on a 1-MA Linear Transformer Driver (LTD)*

Post-hole convolutes are used to combine current from several parallel transmission lines, such that there is a low-inductance path to a single anode-cathode gap at the load. Experimental observations of the post-hole convolute are difficult to make on large systems, such as the Z-Machine at Sandia National Laboratories. A single post-hole convolute has been designed as the load for the 1 MA LTD at U. of Michigan. The geometry of the design allows diagnostic access to the post-hole region. The goal of these experiments is to monitor plasma formation in the convolute and to measure the current losses as a result of that plasma. Diagnostics under development for this experiment include B-dots for current measurement, optical spectroscopy for plasma composition, temperature and density measurements, and pinhole and laser diagnostics for imaging plasma dynamics. Experimental results will be compared to Particle-In-Cell simulations of this system using MAGIC PIC.* Research supported by Sandia National Labs subcontacts to UM. MRG sponsored by SSGF through NNSA and JZ sponsored by NPSC through DOE. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US DOE's NNSA under contract DE-AC04-94AL85000.