Analysis And Simulation Of Spectra From Laser-produced Plasma Based On Collision Radiation Model

A laser-produced plasma(LPP)ablated by a nanosecond laser pulse is neither homogeneous nor static in the expanding and cooling process in a vacuum.LPP has the characteristics of intense burst of radiation over a broad spectral range,coexistence of various charge state ions,complex atomic process and the spatial gradient of temperature and density is larger.The study on structures and radiation transport properties of highly charged ions from laser produced plasmas is very important for plasma diagnosis of controlled thermonuclear fusion,design of new extreme ultraviolet and soft X ray source,optimization of high-power laser ablation ion source,simulation of astrophysics plasma and so on.In this thesis,a spatio-temporally resolved laser-produced plasma spectroscopy setup has been established.By using this setup,the a spatio-temporally resolved EUV emission of Plasma produced by high purity solid target.Based on the time-dependent collision radiation model,we have compiled a program for solving the distribution of charge state and the evolution rule of excited state population in laser-produced plasma.By using the present program,plasma temperature,electron density,and other state parameters,and the evolution of plasma state with a time delay,were obtained.The expansion and cooling processes of LPP were accurately reproduced.This program can quickly diagnose plasma and therefore it can be used as an effective tool in laser produced plasma diagnosis.Combined with experimental measurement and theoretical simulation,we have accomplished some following works:(1)The EUV spectrum of Cu ions from laser-produced plasmas ranging from 6.5 to 16 nm is obtained by using a spatio-temporally resolved laser-produced plasma spectroscopy setup.Then we used the Cowan program to identify the experimental spectrum that mainly comes from 3d-4f and 3d-5f transition arrays of Cu6+ Cu+9 ions.Combining the atomic structure parameters and the distribution of the charge state in the plasma,the experimental spectra were simulated successfully.The evolution information of state parameters such as electron temperature and density in laser-produced Cu plasmas has been obtained.(2)The Time resolved spectrum of Al ions from laser-produced plasmas is obtained by using a spatio-temporally resolved laser-produced plasma spectroscopy setup,then we used the Cowan program to identify the experimental spectrum.Combining the atomic structure parameters and the time-dependent CR model for plasma analysis and simulation program.We have studied the radiation and kinetic characteristics of the laser-produced Cu plasmas,and obtained the evolution information of the plasma temperature,electron density and charge state distribution with time.The effect of photoionization process on ionization balance is also discussed.