Chemi-ionization in neon plasma

The density of electrons formed in binary collisions of 2p(5)3s neon atoms was measured in the afterglow of a low pressure glow discharge by observing the high energy tail of the electron energy distribution function (EEDF) using a Langmuir probe. In the afterglow, the bulk plasma electrons thermalize but the density of 2p(5)3s neon atoms remains significant. In an ionizing collision, a pair of these atoms releases high energy (similar to11.6 eV) electrons which form a characteristic peak in the EEDF. Simultaneously with the chemi-ionization electrons, the densities of 1s(2), 1s(3), 1s(4), and 1s(5) neon atoms were independently measured using diode laser absorption spectroscopy. It was found that the data obtained are described well by a single chemi-ionization reaction when the 2p(5)3s configuration is considered a single state. The corresponding rate coefficient, found to be (3.2+/-0.4)x10(-10) cm(3) s(-1) at a temperature of 310 K, is recommended for use in discharge modeling. (C) 2002 American Institute of Physics.