Tungsten Planar Wire Arrays On Michigan’s Ltd Generator

Since the first wire-array tungsten (W) experiments on Z at SNL, where the record x-ray power of 200 TW and x-ray yield of nearly 2 MJ were achieved
¹
, such arrays were actively studied and considered for various applications including inertial confinement fusion (ICF)
²
. More recently, W Double Planar Wire Arrays (DPWAs) were suggested and tested for indirect drive ICF
³
. DPWA consists of two parallel planes of wires of the same (uniform) or different (mixed) wire materials. W DPWAs have previously demonstrated the highest (among PWAs) radiation yield (up to 30 kJ), compact size (few mm), and strong electron beams at the Universityscale high-impedance generator
³
. During the last few years we have reported on the outcome of the experiments with uniform and mixed Al and stainless steel DPWAs on the University of Michigan’s low-impedance Linear Transformer Driver (LTD) MAIZE generator. Here we present the results of the most recent campaign with W and W/Al DPWAs recorded using filtered x-ray diodes, x-ray spectrometers and pinhole cameras, and a twelve frame shadowgraphy system. For the first time, implosion of W wire arrays on LTD generator in USA was demonstrated and analyzed. In particular, uniform W and mixed W/Al DPWAs with a mass up to 87 μg arranged in various configurations were successfully imploded at the current of 0.5 MA during $\sim 210$ns. The most interesting results were obtained with W/Al DPWAs where a long-term standing shock wave was consistently formed at the W side, which was also observed at the high-impedance Zebra generator at UNR. In addition, soft (4-7 Å) and hard (1-2.4 Å) line radiation was substantially suppressed by including the Al plane.