STP689: Investigation of Surface Breakdown Mechanism in IR-Optical Materials

    Kovalev, VI
    USSR Academy of Sciences, Moscow,

    Faizullov, FS
    USSR Academy of Sciences, Moscow,

    Pages: 10    Published: Jan 1979


    Abstract

    It has been found that with a decrease in ambient gas pressure, there takes place a decrease of surface breakdown threshold in IR-optical materials under TEA CO2-laser radiation. To explain this fact, a new mechanism of the breakdown has been proposed, which is connected with evaporation of adsorbed water. The breakdown stage has been experimentally investigated and a theoretical analysis has been performed. The dependence of the surface breakdown in NaCl on ambient gas pressure, spot size, frequency and time have been studied. The dependence on the quantity of adsorbed water (surface absorption) has been studied as well. The breakdown thresholds have been measured with a calibrated, photon drag detector by the amplitude of the transmitted pulse. The results obtained are in good agreement with the proposed model.

    Keywords:

    Adsorbed water, breakdown mechanism, IR window materials, NaCl, pulsed TEA CO, 2, laser surface breakdown, pressure, spot size, surface absorption, frequency and time dependence of breakdown thresholds, transmitted pulse


    Paper ID: STP39133S

    Committee/Subcommittee: F01.02

    DOI: 10.1520/STP39133S


    CrossRef ASTM International is a member of CrossRef.