Pulsed power produced counter-propagating plasma flows and the study of shock wave formation for laboratory astrophysical phenomena

We report on counter-propagating plasma flows produced by two vertically opposing conical wire arrays using a compact, low inductance Linear Transformer Driver (LTD) “GenASIS” capable of producing 250 kA in about 150 ns. Laser interferometry and laser schlieren were performed with the use of a Nd:YAG 532 nm laser, with a pulse width of 5 ns. A shock wave formed by jet interaction was clearly observed and remained stationary for at least 50 ns. Interferometry data showed that the ion density of the jets prior to collision was of the order of 2×10¹⁷cm^-3 and a jump in density of ~ 5 was observed at the shock wave region. A lower limit of ~ 100 km/s has been measured for the jet velocity. The ion mean free path has been estimated to be ~ 12 mm, which is larger than the shock wave scale ~ 5 mm, and hence the shock wave approaches the collisionless regime. Magnetic field advection, which can drastically modify the conditions for shock wave formation, will be discussed. Kinetic particle-in-cell modeling using LSP code has also been implemented and benchmarked against the experimental results in order to study the underlying physics of formation and evolution of the shock.