High powers from large diameter wire arrays on the refurbished Z generator

We present results from initial large diameter wire array experiments at the refurbished Z generator. 65mm on 32.5mm nested stainless steel wire arrays were fielded at two different total masses (2.5mg & 5mg). Each array was 20mm tall and had an inner array half the mass of the outer. The experiments were designed to evaluate trends in Fe K-shell power and yield and re-establish previous output, and large diameter tungsten wire arrays are further planned to study total x-ray output. For the 2.5mg nested stainless steel arrays the average total radiated yield measured with Ni bolometers was 1.9MJ. Peak powers of 250TW were inferred using the pulse shape from the Total Energy & Power diagnostic normalized to the bolometer yield. Using x-ray diodes for the pulse shape gave higher peak powers. Over three similar shots, the shot-to- shot variation was 6% in energy and 2.5% in peak power, well within the 30% systematic measurement error. Note that the shots described here were performed at 75% of the potential stored energy of the refurbished Z machine. We will compare the measured total yields and powers to the yields and powers from Stainless Steel and Tungsten arrays at various diameters on the Z generator both before and after the recent refurbishment. K-shell powers and yields were comparable to those from stainless steel experiments prior to the refurbishment, averaging 15TW and 60kJ. Data at 5mg confirmed the expected drop in the total power and K-shell power and yield due to L-shell radiative cooling at increased mass, however the total yield increased by 20% due to improved coupling to the generator.