Measurements of excitation rate coefficients for Al-like ions: Fe xiv, Ni xvi, and Cu xvii

Absolute excitation rate coefficients for Fe xvi and Ni xvi ions ions are measured spectroscopically in the Texas Experimental Tokamak. Previous measurements for the 3d-3p transition array of Cu xvii are verified and the measurements are extended to the 3s3p23s23p transition array of this ion. The experimental rate coefficient for the 3d-3p transition array of Fe xiv is 6.2×10-9 cm3 s-1 at an electron temperature near 160 eV and for Ni xvi and Cu xvii, the values are 4.2×10-9 and 3.8×10-9 cm3 s-1, respectively, at an electron temperature near 240 eV. For the 3s3p2 2P3/23s23p 2P3/2 transition array, the experimental excitation rate coefficient for Fe xiv is 8.2×10-9 cm3 s-1 at an electron temperature near 160eV and for Ni xvi and Cu xvii the value is 5.5×10-9 cm3 s-1 at an electron temperature near 240 eV. The uncertainty in these results is estimated to be 50% (one standard deviation). Computed values of absolute excitation rates in a distorted-wave approximation and Mewe's semiempirical formula are found to be in good agreement with the experimental values.