Investigations of advected magnetic fields in experiments with supersonic plasma flows.

Plasma flows created from the ablation of wires in wire array z-pinches can transport frozen-in magnetic fields. The presence of this advected magnetic field can significantly affect the structure of bow shocks that are formed when obstacles are placed in the plasma flow [1]. This is in contrast to the bow shocks that are present in many astrophysical scenarios where the fields do not dominate the conditions. We will present results of experiments performed using the MAGPIE (1 MA, 250 ns) pulsed power facility at Imperial College, London to better understand and control the magnetic fields transported within the plasma. Plasma flows used in these experiments were created using inverse wire arrays [1] and radial foil [2] configurations. Methods of putting obstacles or grids into the plasma flow to change the magnetic field structures are being tested and various diagnostics including Thomson scattering, laser interferometry, shadowgraphy and magnetic probes were used to characterise the resulting flow and magnetic field. [1] G. C. Burdiak et al., The structure of bow shocks formed by the interaction of pulsed power driven magnetised plasma flows with conducting obstacles. PoP., 2017 (in print). [2] F. Suzuki-Vidal et al., Astrophys. J. 815, 2 (2015)