ELECTRON-IMPACT EXCITATION RATES FOR TRANSITIONS INVOLVING THE N=2 AND N=3 LEVELS OF BERYLLIUM-LIKE NE-VII

Electron impact excitation rates evaluated using the multichannel R-ma trix method are presented for the Be-sequence ion Ne VII. Twenty-six t arget eigenstates consisting of the 6 n = 2 states with configurations 2s(2), 2s2p, and 2p(2) and the 20 n = 3 states with configurations 2s 3s, 2s3p, 2s3d, 2p3s, 2p3p, and 2p3d are included in the expansion of the total wave function. These 26 ionic states correspond to 46 fine-s tructure levels, leading to a total of 1035 possible independent trans itions, Effective collision strengths, obtained by averaging the elect ron collision strengths over a Maxwellian distribution of electron vel ocities, are tabulated for all fine-structure transitions between the lowest n = 2 levels together with those between the n = 2 and n = 3 le vels, for electron temperatures, T, in the range log T(K) = 4 to log T (K) = 6.4, Comparisons are made with other available theoretical data and significant deviations are found to occur. In particular the prese nt results indicate that the excitation rates for many of the forbidde n transitions considered are significantly enhanced by resonances conv erging to the n = 3 thresholds. (C) 1995 Academic Press, Inc.