Collisionality studies of supersonic plasma jets on a 500 kA, 160 ns Linear Transformer Driver

Astrophysical objects such as Herbig-Haro and supernova remnants can produce supersonic plasma outflows. These objects can generate plasma jets through radiative cooling and collisionless shocks. To study plasma jet dynamics, experiments were conducted on CESZAR (Compact Experimental System for Z-pinch and Ablation Research), a >500 kA peak current and 160 ns rise-time Linear Transformer Driver (LTD). Counter-propagating supersonic plasma jets with varying degrees of collisionality were produced by driving two conical wire arrays of different materials; from carbon to tungsten. Collision rates and radiative cooling parameters were measured along with jet velocity and Mach number to investigate how collisionality impacts plasma jet formation. In agreement with previous results [1] obtained in a lower current LTD (GenASIS: 200 kA, 150 ns), it was found that plasma flows from low Z materials produce smooth, temporary stable collisional shocks and high Z materials produce strong, thin, and inconsistent short-lived collisionless shocks. These findings will inform scaling of future experiments to study jet dynamics in larger current systems.