Investigation of a laser-produced atomic beam

Abstract

The acceleration of a thin layer mounted on the rear surface of a thick transparent slab target was shown to be feasible with a laser of moderate energy. Both long (about 1 ns) and short (about 25 ps) laser pulse interactions were investigated. Using a single laser beam with 2 J in a 1 ns pulse it was possible to accelerate an Al layer of thickness <or=1 mu m up to a velocity of 2*106 cm s-1. Atomic beam velocity distributions were measured with a time-of-flight neutral particle detector and a time-gated micro-channel plate neutral particle pin-hole camera. The expanding atomic beam was confined to a very narrow cone, being directed along the normal to the target rear surface and independent of the laser beam axis. Time-resolved imaging of the target rear surface in different spectral bands provided measurements of its temperature and the characteristic scale-length of the atomic beam emission area.