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

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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 3s3p²{→}3s²3p 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 ²{P}3/2→3{s}²$3p ${}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.