Study of the collisional effects and increasing transverse magnetic field on the expansion of a laser produced plasma.

The interactions of laser produced plasmas (LPP) with externally applied magnetic fields provides insights into many physical phenomena such as kinetic energy to thermal energy conversion, instabilities on the surface of highly transient plasmas, and particle acceleration and deceleration in magnetic fields. Our study focused on the effects of increasing magnetic fields and varying ambient pressure on the expansion of the LPP. The experiment was conducted using the Magnetic Dusty Plasma Experiment (MDPX) highly uniform superconducting magnet at Auburn University. The LPP was produced by a 10 GW/cm² laser beam produced by a Nd:Yag pulsed laser operating at the second harmonic (532 nm) and 280 mJ. A carbon rod was used as the target and the plasma plume expanded transverse to the applied magnetic fields. Time evolution images of the plasma expansion were obtained using an iStar ICCD camera. The magnetic field and pressure were varied incrementally from 0.125 to 3 T and 50 mTorr to 300 mTorr, respectively. The main findings were that the critical radius of the plume perpendicular to the applied field was independent of the magnetic field above 1 T, and the primary pressure pushing the plasma past the applied field was kinetic.