Spatiotemporal Evolution of Electron Density in the ZaP-HD Sheared-Flow-Stabilized Z pinch

A four-chord HeNe (Helium-Neon) interferometer is used to measure the electron density of sheared-flow-stabilized (SFS) Z-pinch plasmas produced by the ZaP-HD experimental device. The interferometer uses a Mach-Zehnder configuration, and employs heterodyne and quadrature techniques to improve signal processing. Temporally-resolved, chord-integrated electron density measurements are taken at various axial locations and impact parameters throughout the Z-pinch plasma. Electron density values are extracted from the chord-integrated signals. Measurement locations are selected to gain insight into the spatiotemporal electron density structure in both the axial and radial dimensions of the SFS Z-pinch plasma. Digital holography measurements are used to validate the electron density measurements from the four-chord HeNe interferometer.