The Research Of X-ray Spectrum Of Laser-plasma

In the inertial confinement fusion, the hot and dense plasma produce a lot ofradiations. The emission spectrum includes line spectrum and continuous spectrum.According to the emission spectrum, many properties of plasma can be deduced.X-ray spectrum of laser plasma is a powerful instrument for researching theformation and evolution of plasma and diagnosing the plasma. On the basis of theorymodels of atom, atomic processes in plasma and models ofplasma,.X-ray spectrumof plasma was studied in this paper. Then, the emission spectrum obtained from alaser-irradiated Kr gas-puff target was analyzed and identified. In addition, emissionspectra emitted from the plasmas respectively generated by ns and fs laser irradiatedthe fiat aluminium targets were compared.First, On the XG-â…¡laser device, the 1.06μm laser beam was focused on thekrypton gas-puff target. Then a high-temperature plasma was generated and theX-ray spectrum between 0.525nm and 0.755nm was recorded by using PET crystalspectrometer. Many 4-2 and 3-2 resonance lines were found obvious in the recordedspectrum. Besides, many dielectronic satellites of Ne-like krypton ions andresonance lines of N-, O- and F-like krypton ions were almost found in the recordedspectrum. Taking account of a relativistic multi configuration interaction, CIinteraction and correction of Breit, the 3—2 and 4—2 resonance lines of C- toMg-like krypton ions had been computed by using the COWAN calculation codes.The line wavelength and intensity factors were calculated in detail. A total of 16 lineswere identified. The very agreement between the calculations and experimentalemission spectrum is significative for enriching the spectra of krypton ions. Second, on the SILEX-â… laser device, the 0.8nm laser beam was focused on thefiat aluminium target. The power density achieved. 10¹⁸W/cm² and aluminiumplasma with high density was generated. The X-ray spectrum between 0.6nm and0.85nm was recorded by using RAP crystal spectrometer.The X-ray CCDmemorized the spectrum. Taking account of the quantum efficiency of CCD, theintegral reflection coefficient of RAP and so on, the spectrum was processed.In thedifferent conditions,the orderliness between the conversion efficiencies of Ly-αandHe-αlines and the power density of laser was groped for. The processed spectrumwas compared with the spectrum of aluminium plasma got on the XG-â…¡laser devicein 2004. The broadening ofαlines, IC lines and satellites of He-like aluminiumions change in different conditions. So the broadening of lines are suit for diagnosingthe plasma. This work is heuristic for diagnoses of dense plasma.Finally, the reasons which caused the lines broadening were analyzed. Then, themethods how to use the Doppler width and Stark width to diagnose the state ofplasma are dissertated.