Helium-Neon Interferometry on a Shear-Flow-Stabilized Z Pinch

A 633 nm interferometer provides information on the evolution of the plasma as it passes from a coaxial plasma gun (acceleration) region into a high density pinch (assembly) region. The stabilization of the Z pinch relies on a sheared flow generated by a complex balance between gas and plasma dynamics in the acceleration region. This diagnostic utilizes a 21 mW helium-neon laser passing through a 80 MHz acousto-optic modulator to generate scene and reference beams that are then recombined after interaction with the plasma and input into a high speed avalanche photodetector. Initial results on the FuZE (Fusion Z-pinch Experiment) show a peak line-integrated density of 3.35 x 10 17 cm -2 in the accelerator and 4.83 x 10 16 cm -2 in the pinch. Discussion on the implications of the resulting electron density are presented along with comparisons of the density trend with B-dot probe and other diagnostic data.