Radiative recombination rate coefficients for highly-charged tungsten ions

Partial and total radiative recombination rate coefficients are presented for highly-charged ions of tungsten with closed shells, W 28 + , W 38 + , W 46 + , W 56 + , W 64 + , W 70 + , and W 72 + , as well as for the H-like ion W 73 + and the bare nucleus W 74 + . The temperature range 10 3 – 10 10 K is considered. Calculations have been performed in the framework of the fully relativistic Dirac–Fock treatment of photoionization and radiative recombination processes taking into account all significant multipoles of the radiation field. We assess the influence of multipole effects on recombination rate coefficients as compared with the commonly used dipole approximation. For the first time, we show that the relativistic Maxwell–Boltzmann distribution of continuum electrons should be used at high temperature. This decreases the rate coefficient significantly compared to the nonrelativistic distribution.