Experimental determination of line-intensity ratios for the n=3 to n=2 transitions of O v, F vi, and Ne vii at electron densities in a range of (4"9)×1012 cm-3

This paper reports relative-line-intensity measurements of the n=3 to n=2 transitions for O v, F vi, and Ne vii in an electron density range of (4"9)×1012 cm-3 in a tokamak plasma. Large discrepancies were found between the experimentally measured and theoretically computed values. The discrepancies are due to inaccuracies in the computations of the electron collision strengths from the 2s2 and 2s2p levels to the 2s3p levels, using either the R-matrix method or the distorted-wave approximation.