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Aiming at the requirement of the on-line detailed atomic model in radiation hydrodynamic simulations, we propose a general model, multi-average ion collisional-radiative model (MAICRM), to rapidly simulate the ionization and charge state distribution of hot dense plasma under non-local thermal equilibrium (NLTE) conditions. In this model, an average ion is used to characterize the features of all the atomic states at one single charge state, including the average orbital occupation and the total population of the atomic states. The rate equations for the orbital occupations and the population are derived from the rate equations of the detailed configurations and separated into two sets under the two assumptions: one is the single orbital rate coefficients (including no occupation nor hole number of the relative orbital) that are only dependent on the charge state, and the other is the coupling of the excitation/de-excitation process and ionization/recombination process, which are weak. Namely, the orbital occupation of an average ion is mainly determined by the excitation/de-excitation process under a certain density and temperature; the population of the average ions is determined by the ionization/recombination process with the fixed orbital occupation. The two sets of rate equations are solved sequentially and iteratively until a set of converged orbital occupation and population values is obtained. The interplay between the occupation and the population is implicit in the excitation/de-excitation rate coefficient and ionization/recombination rate coefficient, each of which is a function of electron density and temperature as well as occupation. In this work, using the newly developed method and codes, the mean ionizations and charge state distributions of Fe, Xe and Au plasmas under different plasma conditions are calculated and in good agreement with the experimental results and DCA/SCA calculations. Meanwhile, compared with the DCA/SCA calculations, in which hundreds or thousands of detailed atomic states at each charge state are considered to obtain a converged ionization balance, MAICRM only considers one kind of ion at one single charge state, thus the computational cost of MAICRM is much reduced and lower than that of DCA/SCA. Due to its good degree of accuracy for ionization balance and its low computational cost, MAICRM is expected to be incorporated into the radiation hydrodynamic program to realize the online calculation of detailed nonequilibrium atomic models in the future.

Auger rates for Au were calculated by quasi-relativistic configuration-averaged method, with the wave functions obtained by Cowan’s codes. Firstly, “configuration-to-configuration Auger rates” for He-like to Dy-like gold were calculated. Then “Auger rates for single electron” for average atom model (AAM) with and without l-splitting were both obtained by averaging the configuration-to-configuration rates. Our data were evaluated through the comparison with other results calculated from more detailed codes, including Cowan’s codes, flexible atomic code and fully relativistic codes. The evaluation shows that most of our data are reliable except those with high orbital quantum number l, which were replaced with valid data obtained by other codes.

A collisional?radiative model is developed for population calculations of plasmas in non-local thermodynamic equilibrium. The rate equations in detailed configuration accounting are solved to obtain ion populations. The configuration averaged rate coefficients are used in the rate equations. The cross sections are calculated based on the first perturbation theory. Wavefunctions required in cross section calculations are obtained by the Hartree?Fock?Slater self-consistent-field model. This kinetic model is applied to low- and medium-Z as well as high-Z plasmas. The results are compared with those of other theoretical models and experiments. The comparisons show that the present results of the mean charge state for low- and medium-Z elements agree well with other theoretical ones, while for high-Z elements, the present mean ionization stages are about two stages lower than the experimental ones.

A model is developed to calculate the emission spectrum of non-local thermodynamic equilibrium (LTE) plasmas. The collisional-radiative model is adopted for non-LTE population calculations. Configuration-averaged rate coefficients that are needed in the rate equations are obtained based on the first-order perturbation theory. The Hartree-Fock-Slater self-consistent-field method is used to calculate electron wavefunctions. The present model is applied to the calculation of isoelectronic line-ratio of Cr and Ti, which is useful for plasma electron temperature diagnosis.

Using a detailed configuration accounting model with term structures treated by the unresolved transition array model, we have extensively investigated the opacities of mixture materials. For plasmas at the temperature of 250 eV and density of 1 g/cm3, our calculated Rosseland mean opacities are in good agreement with other theoretical results. A high increase in the Rosseland mean opacity to 2944 cm2/g is achieved for a multi-element mixture compared to the value of 1729 cm2/g for pure gold. Various mixtures at other plasma conditions are also studied.

The authors try to develop a method to calculate the rate of the reverse process of dielectronic recombination that can be used in the rate equations in an average ion model. Based on the detailed configuration accounting (DCA) model, an approximate formula for the above calculation is presented and is tested by the DCA model.

Based on the detailed configuration accounting (DCA) model, a method is developed to include the resonant photoionization and the excitation-autoionization in the non-local thermodynamical equilibrium (NLTE) average atom (AA) model. Using this new model, the mean charge states and the opacity are calculated for NLTE high- plasmas and compared with other results. The agreement with AA model is poor at low electron density. The present results agree well with those of DCA model within 10%. The calculations show that the NLTE effects on opacity are strong.

Based on the detailed configuration accounting model, the authros have developed a method to calculate the rate of excitation-autoionization (EA) in the average atom model and used it in the rate equations. The numerical results show that EA effect is signifficant in high temperature low density plasma and can cause an additional ionization up to 15% of an ionization stage.

A programme is developed to calculate the polarizations of the radiation emitted after electron impact excitation. The fully relativistic distorted-wave method is used in cross-section calculations. The programme is applied to He- and Li-like ions. The calculated values of line polarization are compared with other theoretical results and experimental values. For He-like U, at lower incident energy, the present polarization agrees with the other theoretical ones within 1%, while at higher energy, the differences increase up to about 10%. For He-like Fe and Ti, the present results of polarization degree for most of the lines agree with the experimental data within the experimental error bars. For the Li-like Ti line q (1s2s2p2P3/2 to 1s22s), the present value of the polarization agree excellently with another theoretical one, and both the values are consistent with the measured data within the experimental error bar.

The dipole Bethe logarithmic constants for high-energy ionization cross sections of atoms and ions by electron impact have been calculated using the relation between and the bound-free Gaunt factor . By this method the values of are expanded to n = 50 and the constants calculated previously for the states 1s have been improved.

For the non-LTE system, the mean-free-path for the photon energy flux is calculated with the three-temperature model. The electron occupation probabilities pi are obtained by solving the rate equations. The results are compared with that by using the Fermi-Dirac distribution function and strong discrepancy is found when tγ > 0.1 keV.

A method is presented to calculate the spectral-resolved opacity for non-local-thermodynamic-equilibrium plasmas. With the present method, the configuration population is obtained by solving the rate equations within the framework of configuration-averaged approximation in which the cross sections are calculated based on the first-order perturbation theory. The transition properties are calculated by using the unresolved transition array model. As the illustration, the frequency-dependent opacities of Al and Au plasmas are calculated and compared with the simulation results of the super configuration collisional radiative code. General agreements are obtained and there are some discrepancies for opacity of high-Z elements.

For the non-LTE system the opacity for the photon energy flux κE and the opacity for the photon entropy flux κs are defined. As an example the opacity calculations for a three-temperature plasma is discussed in detail and some numerical results of aluminium are presented.

Based on the average atom model, a non-local thermodynamic equilibrium (non-LTE) model is developed to calculate opacity for mixtures. This model could be applied to high-Z problems. The mean ionization degrees of SiO2 of the present calculation are slightly higher compared with another model for mixtures. As an example, the opacity of Au and Nd mixture is calculated. The results show concrete non-LTE effects and the increase in opacity of the mixture is shown clearly.

In this article, the X ray special line radiation from Z-pinch Al plasma is calculated by using non-local-thermodynamic-equilibrium model (NLTE) based on digital energy level. The electron density of Z-pinch plasma at centre is obtained. The single plasma state parameter cannot well describe the special line radiation. In the next step, the Z-pinch plasma is divided into two parts: high electron temperature plasma at centre and low electron temperature plasma. The superposition of radiations from two parts is analyzed, and modified calculation result is presented. The calculation results are significantly improved after the superposition of radiations from two parts has been taken into account.

According to the experimental results of spectrum diagnosis made on Qiang-Guang-I generator, we report a method to separate and diagnose Z-pinch plasma radiation spectrum. Spectral lines and different continuums are separated from experimental results and electron temperatures can be acquired. Results show that continuums are superposed by radiation of high electron temperature plasma at the centre field (Te=290.7 eV ± 1.2 eV) and radiation of lower electron temperature plasma at shell region (Te=95.3 eV ± 8.3 eV). Spectral lines reflect the information of high electron temperature plasma at the centre field. According to the calculation by using NLTE model, the electron temperature of such a plasma is in the range of 299–313 eV. The diagnose result by spectral lines is identical with the continuum's results.

A target designed for opacity studies of dense plasmas by laser direct heating and self-backlighting technique was presented and tested. The backlight source and sample plasma were generated by directing a frequency-tripled Nb-glass laser onto an Au/CH/Al/CH multilayer target on the XG-II laser facility, and the absorption of the sample plasma was obtained by measuring the attenuated backlight spectrum of the sample plasma. One-dimensional radiative hydrodynamic code Multi-1D was used to simulate the laser heating of the multilayer target, and the temperature and density profiles in the target were given. Experimental data were compared with the theoretically calculated spectra using the detailed-term-accounting model, which showed a temperature range from 20 eV to 70 eV in the sample plasma, a result in quite good agreement with the Multi-1D simulations.

In order to interpret the spectrum of a photoionized Si plasma, we calculate the level populations and emissions using a collisional-radiative equilibrium model with detailed atomic data. In our calculations, levels with principal quantum number up to 9 are included and the electron impact processes are also taken into account. The peak around 1855 eV, which is not reproduced in the previous simulation, is obvious in the present results. Spectra analyzing shows that this peak mainly comes from the intercombination line of He-like Si. Our calculations indicate that the electron impact processes enhance this intercombination line about once, although the electron temperature is pretty low.

Based on the detailed configuration accounting model (DCA), a method is developed to calculate the rate of the resonant photoionization (RP) in the average atom (AA) model. Using this method, the RP rates are calculated for an average ion and compared with DCA calculation. The comparison shows the reasonableness of the proposed method. The RP process is included in the AA rate equations and the numerical results show that RP can cause an additional ionization up to 10% or so in some cases.

The formulae of photon angular distribution and polarization degree for radiative recombination are presented to include the contribution of multipoles and their correlations. A fully relativistic code is then developed to calculate the photon angular distribution and polarization. The calculated polarization degree and differential cross-sections agree well with that of Scofield's results within 10%. The effects of multipoles on polarization and angular distribution are investigated. The polarization and the angular distribution become asymmetric when the multipoles are accounted as the electron energy increases.