Characteristic Effects of Pulsed Power Generators of Different Architecture on the Implosion Dynamics of Mid-Atomic-Number Double Planar Wire Arrays

Abstract

Planar wire arrays (PWAs) have been studied on both the University of Michigan’s (UM’s) low-impedance linear transformer driver (LTD), MAIZE ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.1 \Omega $ </tex-math></inline-formula> , 0.5–1 MA, and 100–250 ns), and the University of Nevada, Reno’s (UNR’s) high-impedance Marx bank generator, Zebra ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.9 \Omega $ </tex-math></inline-formula> , 1 MA, and 100 ns). Results with aluminum (low-atomic-number) and tungsten (high-atomic-number) double PWAs (DPWAs) were compared previously; thus, DPWAs made of brass (an alloy of mid-atomic-number elements copper and zinc) were recently selected for study to get a more complete understanding of low-to-high atomic number DPWA implosions on MAIZE. As the LTD is a relatively new pulsed power architecture, comparing results from traditional generators (such as Marx banks) will help us to better understand both technologies. Experimental diagnostics included an absolutely calibrated filtered polycrystalline diamond detector (PCD), filtered Si-diodes, X-ray pinhole cameras, spectrometers, and optical shadowgraphy systems. Time-dependent inductance modeling on the MAIZE LTD was derived from the measured current trace. Radiative and implosion dynamics of brass DPWAs on the MAIZE LTD are presented and compared with previous results on the Zebra Marx generator. Implosions on the MAIZE LTD featured a longer than expected current rise time that was heavily dependent upon the load inductance, as well as a longer pinching process and X-ray emission time than comparable DPWA implosions on Zebra; however, implosions on MAIZE produced L-shell plasmas comparable in characteristics with previous studies on Zebra.