Abstract:
An experimental investigation was made of the processes of interaction of radiation from an XeCl excimer laser (λ = 308 nm, τ = 20 ns) with aluminum. The threshold of formation of an erosion plasma in vacuum (q* = 200 MW/cm2) was independent of the number N of the pulses. The threshold q* in air depended strongly on N and could fall to 70 MW/cm2, due to the formation of a strongly absorbing layer on the target surface. The depth of the layer removed by radiation of intensity q ≈ 1 GW/cm2 could reach 1 μm per pulse. The average optical thickness of a plasma created by one pulse was of the order of 0.3 at λ = 308 nm. Evaporation by XeCl laser radiation increased the aluminum absorptivity by a factor of 3–5. The erosion plasma temperature did not exceed 2 eV for q ≈ 1 GW/cm2. A general energy balance was determined for the laser radiation–target–plasma in vacuum.