Distribution and Evolution of the Magnetic Field and Current in Single-Wire Z-Pinch Measured by Faraday Rotation Diagnostic

The current distribution and development in single-wire Zpinch at the ablation, implosion, and stagnation were studied using a Faraday rotation diagnostic on the ' Qin-1 ' pulsed power device. The electron density was measured by a 532nm Mach-Zender interferometer, and the Faraday rotation was calculated by a three-channel polarimeter including two Faraday channels and a shadow channel at the wavelength of 1064 nm. The Faraday and shadow channels are separated using two non-polarizing beam splitters with a specific splitting ratio and analysed at angles ±β either side of extinction, resulting in a two-fold improvement in contrast information for the Faraday images. The spatial and temporal distribution of the magnetic field in plasma was measured at ablation, implosion and stagnation, thus the current carried by the plasma was figured out. It is found that 70% of the current is mainly concentrated in the shell at implosion, and there is a significant inside-out current transfer at stagnation. Also, the axially non-uniform distribution of the current affects the MRT instability of the plasma, which is consistent with the simulation of the snowplow model.