Study of a laser-produced plasma by Langmuir probes

The structure, the parameters and the expansion of the plasma produced by focusing a 7J, 20 ns Nd-glass laser on stainless-steel and glass targets suspended in a high-vacuum chamber were investigated by Langmuir probes. It was observed that the probe signals consisted of a photoelectric-emission peak and the main plasma from the target. The flow velocity, density and electron temperature of the plasma were determined. The expansion of the plasma was found to be adiabatic, yielding gamma = 5/3. The spatial distribution of the plasma was observed to be strongly anisotropic. (author)