INVESTIGATION OF THE MECHANISMS ASSOCIATED WITH GAS BREAKDOWN UNDER INTENSE OPTICAL ILLUMINATION
Semi-annual rept. for 1 Jan-31 Jul 1965
UNITED AIRCRAFT RESEARCH LABS EAST HARTFORD CT
Pagination or Media Count:
The focused high-intensity optical frequency beam from a Q-spoiled ruby or neodymium laser is used to cause electrical breakdown in a test gas, and the ionization produced is examined as a function of the gas, pressure, volume within which the breakdown occurs, and frequency of radiation. With both ruby and neodymium radiation, for the gases studied breakdown in air was observed to require the highest field strength with successively lower field strengths required for breakdown in neon, helium, and argon. Studies have been carried out to examine the attenuation of the laser beam by the breakdown plasma. For beam intensities slightly above the breakdown threshold, it is observed with both ruby and neodymium incident radiation that more than half of the laser beam energy can be absorbed in the plasma produced by the breakdown and that over 90 attenuation of the laser beam can occur at later times in the optical pulse. Measurements of the attenuation of an optical beam by the breakdown plasma at times subsequent to the incident giant pulse have been made using the cw beam from a helium-neon laser.
- Fluid Mechanics