Fe Plasma Spectroscopy Induced By Femtosecond Double-pulse Laser

Laser-induced plasma spectroscopy is a widely used new analysis technique.With the development of laser spectroscopy technique, femtosecond laser has beenintroduced into the laser-induced plasma spectroscopy (LIPS), as known asfemtosecond laser-induced breakdown spectroscopy (FsLIBS). But the pulse laser isnot accurately stabilized and unrepeatable for the laser radiation, including the samplevolume effect and detection noise which lead to high error level. To solve thisproblem, we used double-pulse to enhance the signal level and then suppress the noiselevel. Our method will dramatically improve the accuracy of laser-induced plasmaspectroscopy.This thesis included four parts. Firstly, we introduced the character andapplication of laser-induced plasma spectroscopy, and proposed our double-pulsefemtosecond laser-induced plasma spectroscopy. Second, we described the principleof the laser-induced plasma spectroscopy in detail, the methods for analyzing thesample and calculating electron temperature and electron density are also discussedhere. Thirdly, we showed the results of double-pulse femtosecond laser-inducedplasma spectroscopy of Fe, and the analysis based on selected three spectra lineslocated between410-445nm is proceeded. We used Boltzmann Plot to calculateelectron temperature and Stark broadening to calculate electron density with432.58nm line. Finally we obtained the dependence of electron temperature and electrondensity with the double-pulse delay. And the experimental condition is discussed forlocal thermodynamic equilibrium. In summary, we concluded the motivation andperspective of our research in the last part.