MHD Simulations And Experimental Measurements of Bow Shocks And Kink Instabilities In Laboratory Plasma Jets

Recent experiments on the University of New Mexico’s HelCat (Helicon-Cathode) Dual Source Plasma Device have focused on understanding bow shocks in low density (1e14 cm^-3), high temperature (10-15 eV) plasma jets with M=3-5. The jet is formed by a coaxial plasma gun orthogonal to the HelCat chamber which ionizes and accelerates ionized argon gas injected through a fast puff valve. This allows experiments to study the transport of plasma jets and bubbles into varying background conditions such as external magnetic fields and background plasmas. Previously. the stability of the jet against the kink instability was studied through the use of an experimentally measured safety factor |q|, utilizing the ratio of the azimuthal magnetic field to the normal field of the jet. Recently, an imaging campaign of the jet flow interrupted by a solid object measured the formation of the bow shock and turbulent structures. Images also revealed the presence of a kink instability which could be stabilized using the background HelCat Magnetic field. Numerical modelling using the eXtended-MHD (XMHD) code PERSEUS** is underway in order to understand some dynamics of the experimental observations. Results of the initial modelling effort for the jet stability and bow shock will be presented along with comparisons to experimental data.