Plasma creation from thin aluminum targets by a TEA-CO2 laser

Abstract

The results of a study of the plasma produced by focused TEA‐CO₂ laser radiation on aluminum foil targets are presented. Streak photography, interferometry, and charge collection measurements are used to describe the time and space evolution of the plasma. A maximum plasma temperature of 30 eV, deduced from the ion expansion energy, was obtained for an incident flux of 10¹⁰ W/cm². The electron density remained below cutoff throughout the interaction. For thick targets the plasma production can be described by using a self‐regulating process. For thin foils the plasma becomes transparent during the laser pulse and the hydrodynamic expansion can influence the results. In this latter case temperature scaling laws based on an integrated inhomogeneous spherical model give good agreement with the experiment.