Interferometric plasma density measurements on the Fusion Z-pinch Experiment FuZE

The Fusion Z-Pinch Experiment (FuZE) is a sheared flow stabilized (SFS) Z-pinch experiment investigating the scaling of SFS Z-pinch plasmas towards fusion conditions. Sustained neutron production has been measured from cylindrical plasmas[1]. As the fusion yield increases, efforts are underway to understand the pinch dynamics. This will require measurements of the plasma density. Density measurements are possible with 2 unique interferometers: A digital holographic interferometer (DHI) and a He-Ne interferometer. The DHI uses a Nd:YAG laser with a digital camera to produce holograms from the plasma assembly region. Digital holograms are numerically reconstructed to obtain the chord-integrated electron density of the compressed plasma. Radial density profiles are reconstructed from these chord-integrated electron density data. The He-Ne Interferometer is a multi-chord (8), heterodyne, quadrature, Mach-Zehnder interferometer. Each chord produces a line-integrated electron density measurement through the plasma. Chord-integrated density and radial density plasma data are presented from FuZE. [1] Y. Zhang et al., PRL 122, 135001 (2019).