Dynamics of Colliding Homogenous and Heterogenous Plasmas Produced by Nanosecond-Laser Ablation

A systematic investigation of the expansion dynamics of plasma plumes generated by two laser beams operating on homogenous and heterogeneous targets was undertaken using a technique involving fast-gated intensified chargecoupled device imaging. Our experiments present the results on the temporal, spatial and semi-spectrally imaging of colliding plasmas of Aluminum and Silicon targets. The aim of the work presented here is to further advance and study colliding plasma techniques, as well as other methods to realize and control species density and expansion, with a view to a deep understanding of these complex mechanisms and optimize emission in the visible wavelength range. The analysis is focused on describing the velocity of the expanding plasma front for the interaction zone where the present results found the expansion velocity of the stagnation layer increases with time, also the fact that the laser energy reduces the velocity. All investigations focus on studies of colliding laser-produced plasmas (CLPP) characterizations formed on wedgeshaped targets where the angle of the wedge varies from 180 degrees to 80 degrees. Time- resolved emission imaging was employed to track the size, shape and velocity of the stagnation layer which might act as a signature of hard versus soft stagnation. Moreover, this work investigated the effect on the homogeneity of the stagnation layer with the target angle. The analysis suggests that there is significant collisional reheating of the stagnation layer followed by radiative recombination as well as this study provides a considerable amount of detailed data related to expansion velocity of the interaction zone which extends the Colliding plasma systems understanding of the behavior of species within CLPP.