UC San Diego

The plume dynamics in the presence of an ambient gas is very intriguing physics. The expansion of a laser-produced plasma in the presence of an ambient gas leads to internal plume structures, plume splitting, sharpening, confinement, etc. We investigated propagation dynamics of an expanding tin plume for various spot sizes using a fast visible plume imaging and Faraday cup diagnostic tools. Our results indicate that the sharpening of the plume depends strongly on the spot size. With a smaller spot size, the lateral expansion is found to be higher and the plume expansion is spherical while with a larger spot size the plume expansion is more cylindrical. Analysis of time resolved imaging also showed internal structures inside the plume.