Time Domain Quadrature Interferometry Diagnostics on X-ray Diodes Driven by the RITS-3 Generator

Abstract

This paper describes the setup, operation, data analysis procedures, and data results of a two-color (lambdaldr = 532 nm and lambdaldr = 1064 nm) quadrature laser interferometer used for the measurement of plasma densities produced by diverse x-ray diodes driven by the RITS-3 generator at Sandia National Laboratories. The nominal non-amplified signal resolution of the interferometer is of the order of 10-3 wavenumbers with the possibility to increase the sensitivity to the limit of detector shot noise of possibly 10-5 wavenumbers. The design is based on a Mach- Zehnder configuration and the NRL high sensitivity two- color interferometer. The quadrature interferometer is a space resolved instrument (< 1 mm spotsize) that provides the probed plasma line integrated index of refraction time history. The advantages of the quadrature interferometer are the ability to make a measurement regardless where the relative phase value of the interference pattern is when the measurement occurs and the ability to resolve fast phase changes over the slower phase envelope produced by external thermal and mechanical perturbations.