| Popis: |
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 CO 2 -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. |
