Time of flight measurements on ion-velocity distribution and anisotropy ofion temperatures in laser plasmas - art. no. 016405

Using a 200-mJ, 5-ns, Nd:YAG laser (where YAG denotes yttrium aluminum garn et), time of Right spectra for ions produced from slab targets of carbon, a luminum, nickel, and tantalum were obtained at a laser intensity of approxi mately 5 x 10(10) W/cm(2). The velocity distribution function of ions of ea ch ionization state, at several angles, in the plane of incidence, was inve stigated and was observed to depart significantly from the Maxwell-Boltzman n distribution function. Kinetic temperatures of ions of each ionization st ate were estimated separately at various angles in the plane of incidence a nd were observed to show a highly anisotropic property leading one to concl ude that the equipartition of energy between the plasma electrons and ions has not taken place. The results are discussed and the relevant conclusions are presented.