  The dielectronic recombination rate coefficients of N V and Ne VIII ions have
been measured at a heavy-ion storage ring. The investigated energy ranges
covered all dielectronic recombination resonances attached to 2s -> 2p (Delta
n=0) core excitations. The rate coefficients in a plasma are derived and
parameterized by using a convenient fit formula. The experimentally derived
rate coefficients are compared with theoretical data by Colgan et al. (2004,
A&A, 417, 1183) and Nahar & Pradhan (1997, ApJ, 111, 339) as well as with the
recommended rate coefficients by Mazzotta et al. (1998, A&A, 133, 403). The
data of Colgan et al. and Nahar & Pradhan reproduce the experiment very well
over the temperature ranges where N V and Ne VIII are expected to exist in
photoionized as well as in collisionally ionized plasmas. In contrast, the
recommendation of Mazzotta et al. agrees with the experimental rate coefficient
only in the temperature range of collisional ionization. At lower temperatures
it deviates from the measured rate coefficient by orders of magnitude. In
addition the influence of external electric fields with field strengths up to
1300 V/cm on the dielectronic recombination rate coefficient has been
investigated.
