Demonstration of an amplitude-division soft x-ray interferometer for plasma diagnostics based on diffraction gratings

Abstract

We have performed soft x-ray interferometry of a laser- created plasma using a novel amplitude division interferometer in combination with a tabletop capillary discharge laser operating at 46.9 nm. The soft x-ray interferometer utilizes diffraction gratings as beam splitters in a Mach-Zehnder configuration to generate high contrast interferograms over a large field of view. An advantage of this interferometer scheme is that it can be used at any of the wavelengths covered by presently available soft x-ray lasers. This table-top system was used to probe a large scale (approximately 3 mm long) plasma crated by a Nd:YAG laser. The short wavelength of the probe laser has allowed mapping of the electron density in plasma regions with density gradients stepper than those that could be probed with the fourth harmonic of Nd:YAG for a plasma of this length.