Determination of the Ni XVIII plasma recombination rate coefficient

The absolute radiative and dielectronic recombination rate coefficients for Ni XVIII were measured at the CRYRING storage ring for the center-of-mass energy range 0-43 eV, which covers all (delta)n= 0 core excitations up to the 3p 1/2 and 3p 3/2 series limits. These are compared to an AUTOSTRUCTURE intermediate coupling calculation. The absolute rate coefficients are then convoluted with a Maxwellian temperature distribution to obtain the temperature dependent plasma recombination rate coefficient for the temperature range 10^3- 10^ 7 K. The temperature dependent rate coefficient can be useful as a tool in both astrophysical and laboratory plasma diagnostics where the knowledge of ionization balance and level populations are of interest in deciphering the many emission lines observed and for the evaluation of the plasma temperature via emission line ratios.