LASER-INDUCED DIELECTRIC-BREAKDOWN IN CRYOGENIC LIQUIDS

Spot size and pulse length dependences of CO//2 laser-induced breakdown in the cryogenic liquids N//2, O//2, CO, and Ar are presented. Parameters which affect the dielectric strengths are identified and the results are compared with previous dc measurements. Diagnostic measurements of photoconductivity, fluorescence and laser-induced pressure (acoustic), and density fluctuations to characterize the breakdown processes are reported. These results are relevant to certain nonlinear optical devices that use cryogenic liquids (CO, O//2, N//2, and Ar) as active media.