Low-pressure barrier discharge spectroscopy. afterglow with Ne$_{2}^{+}$, Ne$^{+}$, and Ne$^{2+}$ ions

The radiation of decaying plasma formed by electron–ion recombination processes involving three neon ions: the molecular ion Ne$^{2+}$ and the atomic ions Ne$^{+}$ and Ne$^{2+}$ has been simulated. Such a combination of ions simultaneously involved in the formation of the plasma spectrum was first detected in the afterglow of a pulsed barrier discharge of a cylindrical configuration at neon pressures of less than 1 Torr and electron densities of less than 4 $\times$ 10$^{10}$ cm$^{-3}$. The main attention has been paid to the comparative analysis of the mechanisms of collisional radiative recombination of the Ne+ and Ne$^{2+}$ ions based on the numerical solution of the system of differential equations for the densities of the ions and long-lived excited atoms in the afterglow considering the basic elementary processes in a decaying plasma with pulsed “heating” of electrons. The regularities of the relaxation of the electron temperature from the discharge values of several electron volts to 300 K in the late afterglow have been considered in detail. A comparison of the simulated solutions with the results of the measurements of the spectral line intensities by the multichannel photon counting method shows that, at their good agreement in the case of single-charge ions, an adequate description of the evolution of ion lines requires expanding the available data on the recombination of Ne$^{2+}$ ions.