Study On Laser Produced Plasma State Diagnosis Based On Spectral Line Broadening And Shifting Methods

Laser produced plasmas has been widely used in EUV light source,water window bioimaging,laser-induced breakdown spectrum,laser ion source,laser pulse deposition and many other fields.The research of laser produced plasma state diagnosis technology plays an important role in the development and application of the above fields.In this thesis,by using the high-precision spatiotemporal resolution spectral measurement method and analyzing the spatiotemporal evolution behavior of the characteristic spectral line broadening and line shifting in the experimental spectrum,the laser produced plasmas state diagnosis research based on the spectral line broadening and line shifting method is carried out.The specific work is as follows:1.The causes of broadening and line shifting of laser produced plasmas spectrum lines are explained.In this thesis,the main broadening mechanism of the spectrum line in laser produced plasma,the Stark broadening,is discussed.The Stark broadened semiempirical formula suitable for calculating atomic and single ionized ion lines and the modified semi-empirical formula suitable for higher charged state ion lines are described in detail.At the same time,the causes of other broadening mechanisms,calculation methods and contributions to the spectral line shape are also introduced.And the change law of Be II and Ca II ion line shift with temperature is obtained.2.Using the above-mentioned theoretical methods,the laser produced Al and Si plasma emission spectra were obtained by a visible spectrometer combined with a laser produced plasma time-space resolution spectrometry measurement device.Based on the broadening of the spectrum of Al atom in the air environment,the electron density of laser produced Al plasma at different delay time is diagnosed,the evolution of the electron density of the plasma is obtained,and the spectral line shift is analyzed.Based on the information of high charge state ion spectrum of laser produced Si plasma in vacuum environment,Saha-Boltzmann method and modified semi-empirical formula are used to diagnose the electron temperature and density in the early stage of laser Si plasma expansion in the range of 30-100 ns delay time.3.Based on the broadening of the isolated spectrum of laser produced Ti plasma in EUV wave band,the electron density of laser produced Ti plasma is diagnosed.Finally,the evolution of electron density in the range of 40 ns delay time and 0.2-2 mm from the target is obtained,and the applicability of this method is discussed.The method based on the broadening of high charge state ion spectrum is extended from visible wave band to EUV wave band.