Isotopic enrichment of swift ions from laser plasmas

Summary form only given. In studying the energy distributions of fast ions emanating from pulsed laser plasmas, we observed an interesting phenomenon relating to the isotopic composition of various charge states. Measurements are accomplished using aspherical sector electrostatic energy analyzer that is operated in the time-of-flight mode together with field sweeping. Observations are made along the normal to the ablution target surface and at angles up to 45 degrees away. Enrichment of the lighter isotope by factors of 2 to 20 are observed depending on charge state, geometry, and laser pulse parameters. The effect has been observed for a variety of species in the periodic table including B, Ti, Cu, Zn and Ga. The phenomenon is thought to be due to swift ions in the laser plasma that interact with internal plasma-driven magnetic fields resulting in Larmor orbits that provide a centrifuge-like motion for the isotopes. In this presentation we will examine such a process and discuss its characteristics in relation to what is known about laser-plasma magnetic fields. Application of this process to enrich isotopes in pulsed-laser deposited films will also be discussed.