Analysis of ultraviolet and visible laser effects

In extrapolating UV/visible effects data obtained with small spots to large spots, it is essential to determine the dominant mechanisms. In this report we present analytical results on the dominant effects at high fluence, vaporization of the surface and plasma formation. Under vacuum conditions with an aluminum surface and about microsecond pulses, we find the impulse coupling coefficient due to vapor recoil to be about 3 for XeF and about 6 for KrF at high fluences. The plasma threshold is greater than 25 MW sq cm incident flux and less than 100 sq cm; the exact value depends on assumptions regarding rate constants.