Development Of A Laser Gas Density Probe

An optical system based on the schlieren technique has been developed to study the temporal behaviour of the neutral gas density inside a spark gap switch after breakdown. The device incorporates an array of laser beams, which are used to probe discrete points within the test volume. Fluctuations in gas density, and therefore refractive index, result in beam deflection, which is detected by a neutral density wedge. Two methods of schlieren profile analysis are discussed and preliminary measurements are presented. These take the form of shockwave and debris expansion rates, and limited information on gas density profiles.