Thermophysical and gas-dynamic characteristics of laser-induced gasplasma flows under femtosecond laser ablation of titanium in vacuum

We report the results of experimental investigation of thermophysical and gas-dynamic characteristics of the gas-plasma flows induced by ultrashort (45–60 fs) laser pulse irradiation (the radiation wavelength $\lambda =400, 800$ nm) of a titanium target in vacuum ($\sim5\times10^{-4}$ mbar). The use of combined interferometric technique and complex experimental data processing allowed us to estimate the momentum coupling coefficient (Cm $\sim10^{-4}$ N W$^{-1}$), the efficiency of laser energy conversion to the kinetic energy of the gas-plasma flow (65%–85%), the spatiotemporal distributions of the particle density (n$_e=10^{18}$–$10^{20}$ cm$^{-3}$) and velocity (GuH=4–9 km s$^{-1}$), the static (10$^6$–10$^8$ Pa) and total (10$^7$–10$^{11}$ Pa) pressure and temperature (T=7–50 kK) in the flow. Our data are compared with published data obtained by other methods.