Laser-induced breakdown of argon at 0.35 μm

Laser-induced breakdown of argon and other gases at a wavelength of 0.35 {μ}m has been measured in the pressure range 200 to 2000 Torr. The results of short-pulse (τₚ=0.4 ns) and long-pulse (τₚ=500 ns) measurements in argon indicate that at $p=1$ atm the breakdown threshold Iₜₕ scales as τₚ^-0.7. Practically complete absorption of the laser beam by the broken-down plasma has been observed at the highest pressures studied. A model for breakdown in Ar is described which gives satisfactory agreement with the data.