Formation of Episodic Magnetically Driven Radiatively Cooled Plasma Jets in Laboratory Experiments

Abstract

We report on experiments in which magnetically driven radiatively cooled plasma jets were produced by a 1 MA, 250 ns current pulse on the MAGPIE pulsed power facility. The jets were driven by the pressure of a toroidal magnetic field in a “magnetic tower” jet configuration. This scenario is characterized by the formation of a magnetically collimated plasma jet on the axis of a magnetic cavity, confined by the ambient medium. The use of a radial metallic foil instead of the radial wire arrays employed in our previous work allows for the generation of episodic magnetic tower outflows which emerge periodically on timescales of ∼ 30 ns. The subsequent magnetic bubbles propagate with velocities reaching ∼ 300 km/s and interact with previous eruptions. This setup also allowed for the addition of a neutral gas above the foil in order to study the effect of the ambient density on the dynamics of both the early time hydrodynamic jet formed from plasma ablated from the foil and of the subsequent magnetic tower outflows.