Radiative recombination data for tungsten ions: I. W24+–W45+

Abstract

We present new accurate data on radiative recombination and photoionization cross sections, radiative recombination rate coefficients, and radiated power loss rate coefficients for twenty tungsten impurity ions in plasmas that are of importance for the ASDEX Upgrade tokamak. Our calculations are based on the fully relativistic treatment of photoionization and radiative recombination. The Dirac–Fock method with proper consideration of the electron exchange interaction is used. All significant multipoles of the radiative field are taken into account. The radiative recombination rates and the radiated power loss rates are found using the thermal average over relativistic cross sections provided the continuum electron velocity is described by the relativistic Maxwell–Jüttner distribution. The photoionization and radiative recombination cross sections are given in the electron energy range from 1 eV to ∼80 keV. Partial cross sections for ground and excited states are approximated by a simple analytical expression involving five fit parameters. The radiative recombination and radiated power loss rates are determined in the temperature range 104–109 K. The total radiative recombination rates are fitted in this range by an another analytical expression with four fit parameters.