Study On The Population Kinetics And Radiative Properties Of Non-local Thermodynamic Equilibrium Plasmas

The radiative properties of plasmas are of great significance in the research field such as inertial confinement fusion (ICF), magnetic confinement fusion, astrophysics, X-ray and laser physics. It's important to consider the effect of non-local-thermodynamic-equilibrium (NLTE) on population kinetics in order to obtain accurate radiative properties. The collisional-radiative(CR) model based on detailed-level-accounting (DLA) and detailed-configuration-accounting (DCA) is established, respectively and is used to investigate the population kinetics and radiative properties of NLTE plasmas. As applications, the CR model based on DLA method provides a useful tool of diagnostics for temperature in inertial confinement fusion (ICF) by using the K shell emission spectra of argon plasmas. The population kinetics and emission spectra of M band of gold plasmas with open N shell are investigated by using CR model based on the DCA method and compared with the experimental results. A much simpler CR model based on the DCA method is developed, where the atomic data are obtained by analytic formula and is used to calculate the population kinetics of high-Z plasmas very quickly. The evolution of population kinetics of argon plasmas based on the time-dependent CR model is investigated. Besides, plasma-screening effects on atomic structure and radiative opacities are investigated in this paper. The main contents of present paper are as follows:Firstly, a CR model is established based on the DLA method. The effect of an incoming radiative field on the ionization balance of carbon plasmas are investigated. It shows that the ionization degree increases due to the incoming radiative field. However, the effect of the incoming radiative field is getting weaker with the electron density increasing. The effect of hot electrons under the conditions of ICF on the population kinetics and K shell emission spectra of argon plasmas are investigated in detail. It shows that the hot electrons increase the ionization degree. However, the effect are getting weaker with the increase of the temperature of hot electrons. It shows that the intensity of Lyβline of hydrogen-like argon ion is very sensitive to the temperature of hot electrons and therefore it can be used as a tool of diagnostics for hot electrons in ICF.Secondly, a CR model is established based on the the DCA method. The population kinetics and emission spectra of M band of gold plasmas with open-N shell are investigated. The comparison between present work and the experimental results shows good agreement. A CR model based on DCA method, where the atomic data are obtained by analytic formula is established to reduce the calculation time and can be conveniently used for the calculation for high-Z plasmas. The accuracy of autoionization rates obtained by analytic formula is checked by using detailed calculations and it shows that the accuracy of the autoionization rates is low which can lead to discrepancies among different models which use different methods to obtain autoionizaion rates.Thirdly, the evolution of population kinetics of argon plasmas based on the time-dependent CR model is investigated. The relaxation of K-shell excitation autoionization state of Ne-like argon ions is studied in detail.Fourthly, the plasma screening effects on atomic structure, photoionization and radiative opacity are investigated by using Debye model. The plasma screening effects on energy levels, oscillator strength of bound-bound transitions and photoionization cross sections of hydrogen atom are studied. It shows that the order of the energy levels is changed compared with that of isolated hydrogen atom. The photionization cross section of ground state of hydrogen atom shows resonance characteristic when the plasma screening effect reaches a critical condition. The radiative opacity of carbon plasmas under variant temperature and densities is studied. The shift of line position and the change of line strength are discussed.As an end, studies of the diagnostics for conditions of iron and carbon plasmas are carried out based on the DLA method. The condition of a hot iron plasma is diagnosed by using accurate radiative opacity under LTE assumption. It shows that the experimental iron plasma is not in strict LTE and a real fraction distribution is inferred. The ionization balance of a hot dense carbon plasma is diagnosed based on the CR model. The main physical reasons that impact the ionization balance are discussed in detail and it shows that the high temperature radiative field is the main course that departs the carbon plasma from LTE.