Moire deflectometry diagnostic for transient plasma using a multi-pulse N/sub 2/ laser

Abstract

The authors have designed a multi-pulse laser system to measure nanosecond timescale, plasma-density gradients by moire/spl acute/ deflectometry. The complete system consists of four, transverse-excited, atmospheric pressure (TEA) N/sub 2/ laser oscillators and two low-pressure N/sub 2/ laser amplifiers; two oscillator pulses are injected into a single amplifier. The amplified pulses are less than a nanosecond in duration, with a variable, inter-pulse time of 4-10 nanoseconds. Described here, two TEA oscillators and a single amplifier were used to image air-density gradients in an expanding air-shock wave produced by a spark discharge.