Soft-x-ray and x-ray ultraviolet radiation from high-density aluminum plasmas

Abstract

Radiation emission over a wide range (5--5000 A) of wavelengths in a high-density aluminum plasma has been studied theoretically. The atomic model includes explicit treatment of a large number of states and transitions characterizing the line emission from the Al III--Al XIII ions. The state populations are calculated using a set of atomic rate equations describing a plasma in collisional-radiative equilibrium. The ionization state of the plasma is calculated self-consistently with line and continuum radiation transport using a one-dimensional multicell structure for the plasma. A new radiation transport scheme has been implemented in this model based on probability of escape for both line and continuum photons. The total L- and K-shell radiation emission is described as a function of plasma temperature, density, and source size, and is compared to predictions made from corona and local thermodynamic equilibrium models. It is shown that over a wide range of plasma parameters, neither of these two limiting models accurately describes the plasma emission characteristics. Several line intensity ratios from L-shell lines are studied and shown to be useful diagnostic indicators of the plasma temperature and density. Finally, theoretical spectra are calculated and discussed in the context of their comparability with experimental spectra inmore » order to make contact with real plasma radiation signatures and exploit the predictive capabilities of the model.« less