Plasma dynamics and determination of ablation parameters using the near-target magnified imaging during pulsed laser ablation

Pulsed laser generated Fe plasma plumes have been studied near the target surface using time-resolved imaging. A fast gated intensified CCD camera is used to capture the images with a gate width of 2 ns. The plasma plumes were generated using a Q-switched Nd-YAG laser at 1064 nm with a fluence of similar to 2 kJ/cm(2). The expansion studies were done up to a distance of about 5 mm from the target surface. The snow plow and the shock wave models were fitted to the experimental data to estimate the ablation parameters and to study plasma expansion dynamics (i.e. velocity and kinetic temperature) at Ar ambient gas pressure of 1 mbar. The high magnification near-target imaging results showed that the axial plume expansion velocity is about similar to 10(6) ms(-1). A strong shock is also captured near the target at few tens of nano-seconds, which was not observable with moderate magnification.