Magnetic field topology variations in plasmas generated by radial foils

Summary form only given. Radial foil implosions on the COrnell Beam Research Accelerator (COBRA) and MAGPIE [1, 2] are used to understand the magneto-hydrodynamics of astrophysical plasma jets. While this configuration shares geometrical similarities with its celestial counterpart, the topology of the magnetic field may exhibit substantial differences. One possible improvement uses external magnetic fields (using permanent magnets or copper coils) to alter the magnetic field generated by the plasma current and recover more realistic dynamics. The other possibility is to change the shape of the pin cathode. The standard setup uses a single straight pin. Since all the discharge current focuses onto that pin, the magnetic field is azimuthally symmetric during the lifetime of the jet, as is the plasma dynamics. However if the pin geometry is changed, the magnetic field becomes fully three-dimensional, as is often the case in astrophysical plasma jets. Using single and multi-pin setups, we will assess how the magnetic field topology can be changed to yield plasma dynamics which matches that of astrophysical jets more closely. In particular, we will look at the impact of three-dimensional magnetic fields on plasma flows and how they influence the actual structure of the jet. Experimental results will be compared to numerical simulations from the 3D PERSEUS extended MHD computer code. The impact of the Hall effect on the plasma dynamics will be highlighted.