Tuning of stagnation layer properties in colliding laser-produced plasmas

The variations in structural and emission characteristics of the stagnation layer produced by the colliding laser produced aluminium plasmas with different target geometry and inter-seed plume separations in both air and Ar ambient are studied using fast imaging and optical emission spectroscopic techniques. A long, sharp, intense stagnation layer is found in laterally colliding laserproduced plasmas with small inter-plume separation. The time delay of interaction of seed plasmas increases with seed plume separation. An intense stagnation layer is formed by a short time delay in angular target geometry. The degree of interpenetration of seed plasmas is greater in angular geometry since the greater forward expansion velocity of seed plasmas causes the formation of the stagnation layer, whereas in flat targets, it is the lateral velocity. In Ar ambient, the plume gets more confined, and the intensity and interaction time of seed plasmas increases. The spectral line intensity of the stagnation layer decreases with the increase of seed plume separation. The spectral intensity is greater in angular target geometry for the same seed plume separation than for a flat one. Greater intensity and longer emission of spectral lines are the benefits of heavier Ar ambient. Plasma parameters, including electron density and electron temperature, are also measured. The shape, intensity, spectral emission, and formation time of the stagnation layer have been engineered with the seed plume separation, target geometry, and ambient gas.