Background Gas Pressure Dependence of Unipolar Arcing on Soda Lime Glass and Plastic Induced by a CO2 Pulsed Laser
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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An experiment was conducted to determine the background gas pressure dependence of laser induced unipolar arcing UA on soda lime glass and polystyrene plastic. A carbon dioxide pulsed laser was used to produce a power density of 5,2500,000 Wsq. cm., and the background pressure was varied from 1.0 atmosphere atm to 10 to the 8th atm approx .000001 torr. For glass at 1.0 atm, the VA crater density at the damaged areas center was maximum and between 1.0 and 0.1 atm, it decreased linearly as the pressure dropped. UA did not occur outside of the heavily damaged area. Between 0.1 and 0.001 atm, UA occurred outside the heavily damaged area. Between 0.1 and 0.001 atm, VA occurred outside the heavily damaged area and both the center and perimeter crater density remained constant. A wave-like ring burn pattern was observed showing the influence of plasma dynamics on the laser beam propagation. Below 0.001 atm, the UA increased at the perimeter and target center, and peaked at approximately 0. 0005 atm. The crater density remained constant for lower pressures. A proposed model for this interaction is outlined. Laser damage, Theses.
- Lasers and Masers
- Ceramics, Refractories and Glass