Heterogeneous laser ablation and its effect on the formation of a near-surface plasma under the action of pulsed laser radiation

Abstract

The influence of the state of the target surface on the processes of near-surface plasma formation is studied in a wide range of wavelengths and laser-radiation pulse widths. These experiments made it possible to reveal the local character of the initial ablation of the target surface, caused both by surface defects and by the defects that appeared at an early stage of the action of the pulsed laser radiation because of the volume heterogeneity of solids. It is shown that the localness of the breakdown affects the evolution of the near-surface plasma formation. The differences in the character of the formation of the near-surface plasma are revealed when short pulses with rapidly increasing laser-radiation intensity act and when laser pulses with a slowly increasing leading edge act. It is established that the localness of the breakdown affects the evolution of the Rayleigh–Taylor hydrodynamic instability of the contact surface between the target vapor and subsequently the plasma and the gas surrounding the target, compressed by the leading shock wave.