Radiative Recombination Data For Low-Charged Tungsten Ions: Iv. W3+-W13+

The radiative recombination and photoionization cross sections as well as the radiative recombination rate coefficients and the radiated power loss rate coefficients are presented for the low-charged tungsten ions from W3+ to W13+. The data are essential to diagnostic and modeling the divertor plasmas impurities in the ITER tokamak because tungsten has been resolved to use as a plasma-facing material. Partial cross sections and rates are given for the ground and excited electron states with principal quantum numbers n <= 10 and orbital momenta l <= 4 in the wide energy range. Relativistic calculations have been performed taking into account all significant multipoles of the radiative field. Electron wave functions have been found by the Dirac-Fock method. The relativistic Maxwell-Juttner distribution of continuum electrons has been used in calculations of radiative recombination and radiated power loss rates. Photoionization cross sections have been fitted by an analytical expression with five fit parameters. Peculiarities of behavior of the cross sections and rates for low-charged ions as well as ensuing problems of the cross section fitting are considered. The radiative recombination rates are compared with other recent calculations for the low-charged tungsten ions. (C) 2020 Elsevier Inc. All rights reserved.