高気圧下におけるフェムト秒レーザを用いたプラズマの観測

Abstract

Plasma produced by the femtosecound laser in high pressure gas has been studied. The threshold laser power of plasma is measured by viewing. The threshold laser power of plasma decreases with increasing gas pressure. It is thought that both ionization processes, cascade ionization and multi-photon ionization, exist in the plasma production processes by femtosecound laser. The plasma streak image is taken by streak camera. The one plasma plume is made in low gas pressure and the multiple plasma plumes are made in high gas pressure. The one plasma plume has longer lifetime, higher luminosity and is made in focul spot. The multi plasma plumes have shorter lifetime, lower luminosity and made on near a focus point. The number of plasma increases with increasing gas pressure.