Dynamics of a Xe cluster plasma produced by an intense ultrashort pulse KrF laser

Abstract

The dynamics of Xe clusters with initial radius between 10 and 100 Å irradiated by an IR subpicosecond laser pulse is investigated. The evolution of the cluster is modeled with a relativistic time-dependent three-dimensional particle simulation model. The focus of this investigation is to understand the energy absorption of clusters and how the absorbed energy is distributed among the various degrees of freedom. The consequence of the initial cluster radius on the absorbed energy, average charge per atom, mean electron and ion energies, ionization, removal of electrons from the cluster, and cluster expansion was studied. The absorbed energy per cluster scales as N5∕3, and the mean electron and ion energies scale as N1∕3 and N2∕3, respectively (N is the number of atoms per cluster). A significant fraction of the absorbed energy (∼90%) is converted into kinetic energy with comparable contribution to electrons and ions. The energy balance suggests that smaller clusters are more efficient as radiators, while larger clusters are more conducive to particle acceleration. The radiation yield of clusters with initial radius 20–50 Å irradiated by a laser with peak intensity 1016W∕cm2 is determined to be 1%–2%.