Kinetic and spectral descriptions for atomic processes involving autoionizing resonances in high-temperature plasmas

Abstract

An investigation has been in progress on the influence of autoionizing resonances on atomic processes in high-temperature plasmas, particularly those encountered in magnetic- and laser-fusion research and in astrophysics. In the kinetic-theory description, account is taken of the indirect contributions of autoionizing resonances to the effective rates for excitation, de-excitation, ionization, and recombination. A microscopic kinetic-theory foundation is employed for the systematic reduction to the macroscopic radiation-hydrodynamics description. From the spectral perspective, particular emphasis has been directed at radiative emission processes from autoionizing resonances. These processes can give rise to resolvable dielectronic-recombination satellite features, which have been analyzed to determine plasma temperatures, densities, electric and magnetic-field distributions, and charge-state distributions. We also investigate radiative absorption processes, which play important roles in the denser plasmas encountered in laser–matter interactions. Particular emphasis is directed at radiative excitation processes involving autoionizing resonances, which can provide significant contributions to the non-equilibrium ionization structures and to the radiative absorption and emission spectra in the presence of intense electromagnetic fields. A reduced-density-matrix formulation has been under development for the microscopic description of the electromagnetic interactions of many-electron atomic systems in the presence of collisional and radiative decoherence and relaxation processes. A central objective is to develop a fundamental quantum-statistical formulation, in which bound-state and autoionization-resonance phenomena can be treated on an equal footing. An ultimate goal is to provide a comprehensive framework for a systematic and self-consistent treatment of non-equilibrium (possibly coherent) atomic-state kinetics and high-resolution (possibly overlapping) spectral-line shapes. This should enable a unified treatment for a broad class of atomic processes in laboratory and astrophysical plasmas covering extensive density and field regimes.