Material Effects on Laboratory Plasma Jets with Applied Magnetic Fields

In the present research, plasma jets form from Joule heating and ablation of a radial foil (approximately 15 μm thin disk) using a pulsed power generator (COBRA) with 1 MA peak current and 100 ns rise time. We study the effects on jet dynamics resulting from varying an applied uniform axial magnetic field (Bz) from 0 to 2 T. We empirically observe a disruption of the plasma jet collimation. The critical Bz for the disruption depends upon the foil material (Al, Ti, Ni, Cu, Zn, Mo, W). The disruption initiates from the foil surface and is dependent upon material mass as well as the solid electrical or thermal resistivities. We consider how the different foil materials affect the plasma magnetization, radiative losses, and formation time of surface plasma. The axial magnetic field larger than the critical Bz can break the azimuthal symmetry of the foil ablation.