Experimental and numerical study of self-organized shear flows in magnetically driven HED plasma jets

An experimental platform is being developed for the 1-MA, 220-ns rise time COBRA generator at Cornell University to investigate the nature of magnetically driven, self-organized, HED flows and their impact on plasma dynamics and stability by simulating astrophysical jets in a well-diagnosed laboratory experiment. In contrast to previous HED laboratory plasma jet experiments that use radial/conical foils or wire arrays, this experiment uses azimuthally symmetric gas-puff injection. This provides a continuous mass source and allows for free rotation of the jet foot points. Because there is no ablation phase from a dense solid target, the magnetically driven jets develop earlier in the current pulse and can be driven longer without depleting their mass source and disrupting. Flexibility in load design permits the generation of a poloidal dipole field (mimicking a magnetized accretion disk) using permanent magnets or dynamically through a helically twisted cathode. A polarity convolute allows for the reversal of the applied electric field to investigate extended MHD (XMHD) effects. Detailed measurements of flow velocities, temperatures, densities, and magnetic fields will be obtained using optical spectroscopy, laser interferometry, Thomson scattering, magnetic probes, and Faraday rotation imaging. Results will be interpreted using the framework of generalized or canonical helicity, which extends the physics of magnetic flux tubes to canonical flux tubes (a weighted sum of flow vorticity flux and magnetic flux). Here we present the design of the experiment, preliminary experimental observations, and 3D modeling using the PERSEUS XMHD code.