Ionization of metastable neon by electron impact

Abstract

The partial electron impact ionization cross section for metastable neon, Ne * + , has been measured in the energy range from threshold to 200 eV. The crossed-beam experiment used a fast neutral target (both ground state and ground state plus metastable) formed by charge transfer between an 800 eV neon ion beam and neon gas or sodium vapour. The ionization cross section for the 3 P 2 and 3 P 0 metastable components, which are assumed to be equal, was placed on an absolute scale by utilizing the known ground-state cross section and assuming that the beam fractions of the mixed state were statistically distributed. The results are compared with previous experimental and theoretical work.

Calculated Electron Impact Ionization Cross Sections of Excited Ne Atoms Using the DM Formalism

“…1) with the experimental results of Johnston et al [27] and the Born calculation of Ton-That and Flannery [28]. The Ne 3 P 0 state is the higher-lying of the two metastable states corresponding to the first excitedstate configuration of Ne, (1s)…”

“…[28] and the filled squares represent the experimental data of Ref. [27]. The combined statistical and systematic error in the experimental data is about 40% .…”

“…Much less effort has been devoted to the ionization of atoms in excited states. Ionization cross sections have been measured for the metastable rare gas atoms He [4,5], Ne [6,7], and Ar [6] and several calculations using different approximations have been carried out for these targets [8,9,10] including an earlier calculation based on the semi-classical Deutsch-Märk (DM) formalism [11].…”

Modeling of microdischarge devices: Pyramidal structures

“…1 The peak electron density is 3ϫ10 13 cm Ϫ3 on axis centered on the mouth of the MD cavity. The electron density is produced by ionization sources by bulk electrons peaking at 1ϫ10 23 cm Ϫ3 s Ϫ1 and by beam electrons peaking at 7ϫ10 23 cm Ϫ3 s Ϫ1 . The ionization by bulk electrons is sustained in part by an electron temperature which peaks at 10 eV in the high electric field at the edge of the presheath, a region populated by a small number of electrons.…”

“…The Ne(2p) state is radiatively coupled to Ne(1s 24 ) and Ne(1s 35 ) but not the ground state. Electron impact cross sections for excitation were largely taken from studies by Lin et al 19,20,23 In the following discussion reference will be made to behavior obeying Paschen's law for which breakdown voltages are a minimum at a characteristic value of pd. 33 The breakdown voltage increases at lower pressures due to the longer mean free paths reducing opportunity for ionization, and at higher pressures due to higher collisionality.…”