SPACE AND TIME-RESOLVED ELECTRON-DENSITY AND CURRENT MEASUREMENTS IN A DENSE-PLASMA FOCUS Z-PINCH

Plasma density and current profiles in a Z-pinch are important paramet ers to understand the implosion and radiation physics. This paper desc ribes measurements of electron density and current at radii of greater than or equal to 200 mu m from the axis of a dense plasma focus (DPF) pinch plasma that is imploded by a approximate to 0.3 MA current puls e, These measurements use laser interferometry and polarimetry, The el ectromagnetic wave propagating through a current carrying plasma will change its phase, polarization state, and propagation direction. Refra ction by electrons bends the wave fronts and changes the propagation d irection; Faraday rotation due to the magnetic field and electron dens ity rotates the laser polarization vector. By measuring these quantiti es simultaneously, the magnetic held and electron density can be separ ately determined. Although the DPP used here is a low current device, the measured densities (less than or equal to 10(20) cm(-3)) and magne tic fields (similar to 100 T) are similar to values expected just outs ide higher current but larger radius Z-pinches, so this technique shou ld be applicable there as well, The techniques described here do not r equire access to the core of the pinch to work; just outside these pin ches the coronal density and self magnetic field are high enough to gi ve reliable data but not so high as to make the measurements difficult .