Electron-impact excitation of Fe20+, including n=4 levels

We have carried out a 200 level close-coupling calculation for C-like Fe us ing the R-matrix method in conjunction with the intermediate coupling frame transformation method. We have generated effective collision strengths ove r T = 8 x 10(4)-8 x 10(7) K for all 19 900 inelastic transitions, which is an order of magnitude larger than has been generated hitherto. We provide i llustrative comparisons with the results of previous workers, where possibl e, and find a broad accord. The consistent and comprehensive set of data th at we have generated (energy levels, radiative rates and effective collisio n strengths) is necessary for the collisional-radiative modelling of metall ic impurities that will arise in the next generation of magnetic fusion rea ctors as well as being of relevance to studies utilizing observations from the high-resolution x-ray satellites Chandra and XMM-Newton.