Elektronennachlieferung in Niederdruckentladungen durch metastabile Stickstoffmoleküle und deren Stoßlöschung durch Fremdgase

Abstract

Oscilloscopic studies of pre-breakdown discharge currents in pure nitrogen and mixtures of nitrogen with other gases show that metastable N2 molecules influence the discharge by releasing secondary electrons when they collide with the electrodes. By this slow process an after current is produced, which lasts a time of milliseconds. It was found that the diffusion coefficient of the metastable N2 molecule is 167 cm2 s−1 ±15% at 1 Torr and 20°C, its radiative life time is larger than 40 ms, and its cross section for deexciting collisions with ground state N2 molecules is smaller than 7 · 10−22 cm2. There is strong evidence that the metastables are in theA3Σu+ state. From measurements in gas mixtures cross sections for deexciting collisions with other molecules are derived. The results are for O2 1.9 · 10−17 cm2, for CO 1.5 · 10−17 cm2, for H2 2.5 · 10−20 cm2, and for CO2 smaller than 5 · 10−20 cm2.