Extended Magnetohydrodynamic Plasma Jets With External Magnetic Fields

In this paper, collimated plasma jets form from Joule heating and ablation of a radial foil (Al 15-mu m-thin disk) using a pulsed power generator (Cornell Beam Research Accelerator) with 1-MA peak current and 100-ns rise time. Plasma dynamics of the jet are diagnosed with and without an applied uniform external magnetic field (similar to 1-T axial B-z produced from a pulsed Helmholtz coil) and under a change of current polarity, which corresponds to current moving either radially inward or outward from the foil's central axis. Experimental results are compared with predictions made by numerical simulations (Plasma as an Extended-MHD Relaxation System using an Efficient Upwind Scheme). The influence of the Hall effect on the jet development is observed under opposite current polarities.