Effects of quasi-cw millisecond neodymium laser radiation pulses on metals

A study was made of the dynamics of formation of laser erosion plasma jets, of the reflection and scattering of laser radiation, and of the brightness temperatures of the target surface as well as of the plasma jets generated as a result of interaction of quasi-cw neodymium laser pulses with Duralumin at moderate laser radiation power densities (q ~1–9 MW/cm²). The observed intermittent formation of the jets (characterized by a period of ~3–5 μsec) was related to the inhomogeneous nature of the evaporation and plasma formation in the range q = 4 –6 MW/cm². A study was made of the dynamics of the arrival of condensed phase particles and of their influence on the screening effect of erosion plasma jets. A correlation was established between pulsations of the intensity of the radiation emitted by these jets (characterized by a period of ≈ 30 –50 μsec), observed in the range q = 4 –6 MW/cm², and pulsations of the intensity of the scattered laser radiation and of the brightness temperature of the jets, which were due to an irregular supply of the condensed phase.