Interferometer Measurements in Pulsed Plasma Experiments

Abstract

The interferometer measurements are extremely informative in plasma experiments allowing direct evaluations of the electron density. The primary goal of the work presented, is to build a laser interferometer which meets the requirements of the highest possible simplicity, economy, convenience and ease of construction. These requirements are successfully satisfied while maintaining high sensitivity (±0.5°–of phase shift) and a wide density range (1014 and 1019 cm-2–line-integrated) of the interferometer. In our experiments we used a low average power (5 mW) He–Ne laser without complicated and costly stabilization or detection environments. The He–Ne laser interferometer with the Michelson arrangement was used to measure the line-integrated plasma densities in various plasma experiments. Time- and spatially-resolved density measurements were performed for a plasma opening switch, a laser produced plasma, an electrothermal launcher and railgun plasmas.