Evolution of plasma loops in a semi-toroidal pinch experiment

Abstract

The FlareLab experiment is a pulsed-power discharge generating magnetized plasma loops similar to a pinch experiment in a semi-toroidal configuration. After gas breakdown along a circular magnetic guide field, the structure expands in its major radius as the plasma becomes highly conductive and the discharge current rises. Photographs, current and electron density measurements reveal a significant broadening in the lateral direction leading to an increasing departure from radial symmetry of plasma parameters in the cross section. It is shown that the luminosity is related to both high electron density and high current density. Simultaneous measurements of current density and electric field reveal a high parallel resistivity of the plasma leading to fast diffusion across the magnetic field. Indications for anomalous resistivity are found by comparison with the Spitzer formula. As the experiment differs from a z-pinch experiment only by the semi-circular shape of the current path, the observed evolution is unexpected and might be of more fundamental significance. V C 2015 AIP Publishing LLC. [http://dx.

Apex Dips of Experimental Flux Ropes: Helix or Cusp?

“…For the gas cones and densities described here, this model predicts that the pileup effect is only significant for valve separation distances less than 12 cm. Although this is an ad hoc model, 2D measurements of the FlareLab initial density profile (Tenfelde et al 2012;Mackel et al 2015) show a peaked density distribution, with contours very similar to those of Figure 4(b), indicating a comparable pileup region at the loop apex. This pileup model is used in Section 5 for the initial conditions of a 3D MHD simulation of the experiment.…”

The dynamics of supersonic plasma flow interaction with the magnetic arch

“…The relation of plasma glow luminosity to electron density under similar conditions is widely used, eg. in the recent experiment [16].…”