Charge-state distribution in a photoionized laser-produced plasma

We present the first x-ray spectroscopic measurements of the ionization balance relevant to astrophysics with intense laser. Independent measurement of the radiation flux indicates values of the ionization parameter ξ ∼ 10 erg cm s-1 and Planckian radiation source of 80 eV to photoionize the nitrogen gas. The observed emission spectra of nitrogen of relatively low density (ni = 1.4 x 1019 cm-3) shows a good agreement with the synthetic spectra by a time-dependent DCA (Detailed Configuration Accounting) atomic model. In this model, it solves the rate equations for level population distributions by considering collisional and radiative atomic processes based on screened hydrogenic model. The jj configuration atomic states and transition probabilities are calculated with Hullac to synthesize spectrum. With this model, we can obtain a reasonable range of the electron temperatures of 20 - 30 eV. Comparisons of charge-state distribution with a non-LTE atomic model FLYCHK show reasonable agreement