THE SELF-QUENCHING PROCESS AND HALF DEEXCITATION TIME OF METASTABLES IN A NITROGEN AFTERGLOW

The dependencies of electrical-breakdown time delays t(d) on the afterglow period tau were measured and the dependence of the mean values t(d)BAR on tau, using the so-called memory curves t(d)BAR = f(tau), was established in nitrogen-filled diodes at 1.3 mbar and 13.3 mbar. The corresponding time-dependent variations of metastable concentration n, i.e. the curves n = F(tau), were derived, where, at afterglow periods exceeding 1 s, the metastable molecules were predominantly in the N2(A3SIGMA(u)+) state. A physical model of metastable de-excitation processes has been proposed and, by solving its differential equations, the following dependencies and constants were obtained: (1) the theoretical dependence of metastable concentration on the afterglow time-the curve n = F(tau), (2) the range of n0, the initial concentrations, which are also saturation concentrations of metastables reached in discharges, (3) the metastable concentration-independent constant k in the equation t(d)BAR = k/n, (4) the dependence of the half de-excitation time T1/2 on the afterglow period, T1/2 = phi(tau), and (5) the dependence of Z on the afterglow period, Z = PHI(tau), where Z is the concentration dependent ratio between the de-excitation rate via binary metastable-metastable collisions and the total rate via all other considered de-excitation mechanisms.