Modeling Of Fast Phase Transitions Dynamics In Metal Target Irradiated By Pico- And Femtosecond Pulsed Laser

摘要

We investigate laser pulse influence on aluminum target in irradiance range 10~9 to 10~(16) W/cm~2, pulse duration between 10~(-8) and 10~(-15)s, Gaussian time profile with wavelength of 0.8 μm. For all computations energy density was 10 J/cm~2. Plasma in the evaporated material is generated at the energy density above 10J/cm~2 as the modeling showed. Long and short laser pulses distinguish by the mechanisms of energy transformation. For short laser pulses there is volumetric energy absorption, together with rapid phase transitions it lead to overheating in solid and liquid states, overheated solid temperature rises up to (6-8)T_m. Under influence of the energy saved in overheated solid, duration of the phase transitions becomes nanosecond, which is several orders of magnitude longer than laser pulse.