Investigation of the characteristics of the initial plasma formation due to interaction of pulsed quasi-cw neodymium laser radiation with metals

An investigation was made of the formation of quasistationary underexpanded laser erosion-plasma jets as a result of interaction of metal targets (Duralumin, brass, bismuth) in air with laser radiation in the form of quasi-cw pulses (λ = 1.06 μm, q _m ~ 0.2–10 MW/cm², τ ~ 1 ms). Two competing regions of initial plasma formation observed under conditions of unstable existence of jets were identified. A study was made of the dependence of the initial evaporation and plasma formation time, and also of the pressure experienced by a bismuth target on the power density of the interacting laser radiation under conditions of non-one-dimensional gasdynamic expansion.