Influence of the microprofile of an-irradiated surface on the appearance of a plasma jet

An investigation was made of the influence of a mechanical treatment of a metal surface on the plasma formation when a target of D16T alloy was irradiated with monochromatic 1.06-μm light pulses of 50-ns duration and 4-J energy. The moment when breakdown was initiated was determined by transversely probing the interaction region with laser radiation and simultaneously recording a stress wave excited in the target using a piezoelectric transducer. A proposed model explains the dependence of the energy density reaching the surface of the sample, by the time a plasma appears, on the surface roughness and agrees with the experimental results.