ACCELERATION OF MICROPARTICLES BY LASER-INDUCED VAPOR EMISSION

Abstract

The interaction of intense laser beams against single charged particles was investigated to determine the possibility of acceleration by surface evaporation. Aluminum particles of 25 μ diam, freely suspended in a time-varying electric field possessing focusing properties, were located within the focal spot (100 μ diam) of the normal output of a ruby laser. The individual laser spikes contribute to the stepwise acceleration of the particle and serve simultaneously for stroboscopic observation of the trajectory. With power densities of 106 W/cm2 and beam energies of a fraction of a joule, the recoil pressure due to the vaporization of the material produced directed velocities of 2 · 104 cm/sec. The present results agree with momentum conservation involving vaporization of a fraction of the particle material.