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 current driver capable of producing 250 kA in about 150 ns. Laser interferometry and extreme ultraviolet imaging were performed to study the collision of the jets. A shock formed by jets interaction was clearly observed and remained stationary for at least 50 ns, after this period a bow shock developed propagating downwards at $\sim$ 20km/s. Interferometry data showed that the ion density of the jets prior to collision was of the order of 2 $\times$ 10$^{17}$cm$^{-3}$ and a jump in density of $\sim$ 4 was observed at the shock region. A lower limit of $\sim$ 100 km/s has been measured for the jets velocity. The inter ions mean free path has been estimated to be $\sim$ 12 mm, which is larger than the shock wave scale $\sim$ 5 mm, and hence the shock is not mediated by collisions. Magnetic field advection, which can drastically modify the conditions for shock formation, will be discussed. Kinetic particle-in-cell modeling using LSP code has also been implemented and benchmarked against the experimental results.