Dielectronic recombination satellite transitions in dense plasmas

Radiative and dielectronic recombination of multiply charged many-electron ions in high-temperature plasmas are usually treated as independent, non-interfering processes. A projection-operator and resolvent-operator approach has been developed to provide a fundamental, unified quantum-mechanical description of the combined electron–ion photo-recombination process. This ordinary Hilbert-space approach provides a valid description in low-density electron–ion beam interactions or in low-density plasmas. By means of the Hebrew University Lawrence Livermore Atomic Code (HULLAC), cross sections for photo-recombination of He-like ions through autoionizing states in Li-like ions have been obtained. For certain transitions, interference effects are predicted in the form of radiatively modified, asymmetric satellite cross-section profiles (or spectral line shapes). A density–matrix formulation has been developed for high-density plasmas, for which collisional and radiative relaxation processes can play an important role. Using Liouville-space projection-operator techniques, collisional and radiative relaxation processes (including cascades) are incorporated on an equal footing and in a self-consistent manner with autoionization and radiative emission. Both time-independent (resolvent-operator) and time-dependent (equation-of-motion) formulations are developed. The density–matrix approach provides a comprehensive description of the broadening of dielectronic satellite spectral lines due to autoionization processes, radiative transitions, electron–ion collisions, and electric and magnetic fields. We plan to adapt HULLAC so that the various elementary electron–ion collisional and radiative transition amplitudes can be used as input data in a generalized collisional-radiative model based on the density–matrix formulation. By means of the density–matrix approach, radiation processes involving resonant and non-resonant transitions in a diverse class of quantized electronic systems can be treated within the context of a single quantum statistical formulation. © 1999