Comparison of Sub- and Super-Alfv\'{e}nic Laser-Plasma Explosions through Low-Density, Magnetized Helium and Hydrogen Plasmas

Recent experiments performed at the University of California at Los Angeles (UCLA) utilized the Large Plasma Device (LAPD) and the Phoenix Laser to drive sub- and super-Alfv\'{e}nic laser-plasma explosions through the uniform, magnetized background plasma of the LAPD. The $30$ J, $5$ ns FWHM Phoenix laser ablated a graphite target to produce a debris plasma that is allowed to expand $>50$ cm and shock the low-density ($1-5\times10^{12}$ cm$^{-3}$), magnetized ($275-600$ G) Helium (or Hydrogen) plasma of the LAPD. An array of seven 3-axis b-dot probes were used to measure the magnetic field compression, expulsion, and fast-diffusion of the diamagnetic cavity formed by the laser-plasma expansion as well as the quasi-parellal launched waves. The diamagnetic cavity structure and influence is studied for various background plasma species (Helium and Hydrogen), magnetic fields, and densities.