Flux of multiple charged metal ions of high energy from plasma produced by a moderate energy laser pulse

Abstract

Studies of the energy spectrum and charge state distribution of ions produced from an Al target irradiated with a laser pulse of moderate energy (90 mJ) and light intensity (4.2 × 1012 W cm−2) and of 27 ps pulse duration are presented. It is established that highly charged ions of the target material up to Al11+ are emitted from the laser produced plasma and evidence of the presence of Al12+ ions is also established. The maximum of the bulk of ion energy distributions approaches 7 keV/Z, which exceeds the values typically observed earlier in plasma produced by laser radiation of the intensity mentioned above. Theoretical examination of the experimental results reveals that the relatively high ion energies can be explained by the specific conditions of the experiments, namely the relatively large diameter of focal spot of the laser beam, appropriate length of the laser pulse, and so on.