Experimental Investigation of Plasma Dynamics in Jets and Bubbles Using a Compact Coaxial Plasma Gun in a Background Magnetized Plasma

Numerous solar and astrophysical observations of jet- and bubble-like plasma structures exhibit morphological similarities, suggesting that there may be common plasma physics at work in the formation and evolution processes of these structures at different system scales. The ideal magnetohydrodynamics (MHD) provide the necessary theoretical basis for employing laboratory experiments to investigate key physical processes in nonlinear astrophysical and solar systems, especially when magnetic fields are present. A coaxial magnetized plasma gun has been designed, installed, and operated in the HelCat linear device at the University of New Mexico. In Region I, a current-driven plasma jet is formed. The plasma column experiences the current-driven kink instability consistent with the Kruskal-Shafranov criterion. When a perpendicular background magnetic field is applied, the jet column length increases with a longer lifetime and appears to show greater stability. Evidence suggests that magnetic tension, caused by the curvature of background magnetic field, leads to an axial sheared flow, which contributes to the stabilization. The calculated results are accordant with the stabilization criterion - reported by other research groups for similar magnetic geometrics. In Region II, spheromak-like plasma formation is verified. When the spheromak plasma propagates into the background magnetic field, the typical self-closed magnetic configuration does not hold anymore. At the upper-side, the Rayleigh -Taylor instability has been observed. The theoretical analysis is present and the instability growth rate has been calculated