On the plume splitting of pulsed laser ablated Fe and Al plasmas

A time resolved imaging study of pulsed laser ablated Fe and Al plasma plumes with specific interest in the splitting of plumes into the slow and fast moving components as they expand through the background argon gas at different pressures is reported. The material ablation was achieved using a Q-switched Nd: YAG (yttrium aluminum garnet) laser operating at 532 nm with a pulse duration of similar to 8 ns full width at half maximum and a fluence of 30 Jcm(-2) at the target surface. Typical time resolved images with low magnification show that the splitting occurs at moderate background gas pressures (0.5 and 1.0 mbar for Fe, and 0.2 mbar for Al plasma plumes). The plume splitting did not occur for higher background gas pressures. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3491410]