Effect of Laser Beam Spot Size on the Dynamics of Ultrashort Laser-Produced Plasma in Vacuum

Abstract

The hydrodynamic expansion features of a laser-produced plasma is governed by initial plume conditions and hence the spot size of the laser beam.1-3 In this work, we investigated the expansion dynamics of a laser produced-plasma as a function of laser spot diameter in a vacuum environment (10-5 Torr) using multiple diagnostic tools. The diagnostic tools used were space-and time-resolved optical emission spectroscopy, 2-D fast-gated self-emission imaging and ion analysis using Faraday cup. The plume dynamics measured for varying spot sizes involves intriguing physics and hence demands detailed investigations, in view of a multitude of applications of laser ablation (LA) including elemental detection (LIBS, LA-LIF etc.), micromachining, laser-welding, nano-structuring, ion beam generation and pulsed laser deposition. © 2018 IEEE.