HEAVY-PARTICLE EXCITATION OF FLUORINE-LIKE FE-XVIII

Cross sections and rate coefficients for excitation of the 2s(2)2p5(2) P3/2-2s(2)2p5(2)P1/2 transition in fluorinelike Fe XVIII by proton (p) , deuteron (d), triton (t), and alpha-particle (alpha) impact have bee n calculated using the close-coupled impact-parameter method. These da ta, in conjunction with R-matrix calculations of electron-impact excit ation rates, are used to derive the theoretical emission line ratio R = I(2s(2)2p5(2)P3/2-2s(2)2p5 2P1/2)/I(2s(2)2p5(2)2P3/2-2s2p6(2)S(1/2)) = I(974.8 angstrom)/I(93.4 angstrom) as a function of electron and he avy-particle number density, and electron and ion temperature, for val ues applicable to tokamak plasmas. A comparison of our results with ob servations of R from the JIPP T-II-U tokamak at the Institute of Plasm a Physics, Nagoya, Japan, for which the plasma parameters have been in dependently determined, reveals excellent agreement between theory and experiment, with discrepancies of typically less-than-or-equal-to 10% . This provides observational support for the accuracy of the atomic d ata adopted in the line ratio calculations.