Spectroscopic and kinetic studies of ionized helium excited by a laser-produced plasma soft x-ray source

[摘要] The work of this thesis describes the experimental set-up and measurements for spectroscopic and kinetic studies of ionized helium gas. An injection-controlled KrF 248nm laser beam focussed to an intensity of 3 $imes$ 10$sp{11}$ Wcm$sp{-2}$ was used to generate highly ionized tantalum plasma. Helium gas was photoionized by the broadband soft x-ray flux from the laser-produced Ta plasma. The possibilities for realizing a short wavelength laser (below 2000A) have been investigated.The spectra of He$sp+$ transitions 4 $o$ 2 and 3 $o$ 2 were experimentally measured by an optical multichannel analyzer, and the time evolution of the fluorescences were observed by a fast response photomultiplier. The effects of helium pressure on the fluorescence were also studied. In addition to the experiments, a kinetic model was developed. The properties of ionized helium predicted by this model are in relatively good agreement with the experimental results.

[发布机构] Rice University

[效力级别] physics