Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas

The expansion dynamics of ion and neutral species in laterally colliding laser produced aluminium plasmas have been investigated using time and space resolved optical emission spectroscopy and spectrally and angularly resolved fast imaging. The emission results highlight a difference in neutral atom and ion distributions in the stagnation layer where, at a time delay of 80 ns, the neutral atoms are localised in the vicinity of the target surface (< 1 mm from the target surface) while singly and doubly charged ions lie predominantly at larger distances, < 1.5 mm and < 2 mm respectively. The imaging results show that the ions were found to form a well defined, but compressed, stagnation layer at the collision front between the two seed plasmas at early times (Δt < 80 ns). On the other hand the excited neutrals were observed to form a V shaped emission feature at the outer regions of the collision front with enhanced neutral emission in the less dense, cooler regions of the stagnation layer.