Electron-impact excitation ofFe21+, including n = 4 levels

Abstract

We have carried out a 204-level close-coupling (CC) calculation forB-like Fe using the R-matrix method in conjunction with theintermediate-coupling frame transformation method as part ofthe RmaX Network programme of work to provide atomic data forx-ray processes. We have also carried out two 125-levelCC calculations to enable us to illustrate theeffect of n = 4 levels on collision data involving n = 2 and 3levels and to provide a quantitative guide to theuncertainty resulting from the partial resolution ofresonances. From our 204-level CC calculation, wehave generated effective collision strengths over T = 105-108 Kfor all 20 706 inelastic transitions, which is an orderof magnitude larger than has been generated hitherto. Weprovide illustrative comparisons with the results of previousworkers, where possible, and find a broad accord. The consistentand comprehensive set of data that we have generated (energylevels, radiative rates and effective collision strengths,including Born limits) is of great relevance to studiesutilizing spectral observations from the new high-resolutionx-ray satellites Chandra and XMM-Newton, as wellas being necessary for the collisional-radiative modelling ofmetallic impurities that will arise in the next generation ofmagnetic fusion reactors.