Langmuir probe study of plasma expansion in pulsed laser ablation

Abstract

Langmuir probes were used to monitor the asymptotic expansion of the plasma produced by the laser ablation of a silver target in a vacuum. The measured angular and temporal distributions of the ion flux and electron temperature were found to be in good agreement with the self-similar isentropic and adiabatic solution of the gas dynamics equations describing the expansion. The value of the adiabatic index γ was about 1.25, consistent with the ablation plume being a low temperature plasma.