Analysis of electron interactions in dielectric gases

Olivet, Aurelio; Duque, Daniel; Vega, Lourdes F.

doi:doi:10.1063/1.2424532

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Spectroscopic study on the vibrational populations of N₂ C ³Π and B ³Π states in a microwave nitrogen discharge

We measured the band spectra (first and second positive systems) of the nitrogen molecule to examine the vibrational and rotational temperatures of the C 3Π and B 3Π states by optical emission spectroscopy. We compared the experimentally measured and the calculated spectra to determine those temperatures of the generated plasma. We generated a microwave discharge nitrogen plasma in a cylindrical quartz tube (26 mm inside diameter) with a discharge pressure of 0.5–1.0 Torr. The microwave frequen...

Luminescent properties and electronic structures of rare earth and alkaline earth borates of REBa₃B₉O₁₈ (RE = Lu,Y)

The samples of LuBa3B9O18 and YBa3B9O18 have been prepared by the solid-state reaction technique at high temperature and their luminescent properties were investigated for both under x-ray and vuv excitation. It is believed that the lattice defects have played an important role on the luminescent performances of the two compounds and the thermoluminescence measurement confirmed the existence of lattice defects in them. The corresponding thermoactivation energy E is estimated to be about 0.36 eV...

We present and discuss results concerning electron interactions processes of dielectric gases and their relationship with the macroscopic behavior of these gases, in particular, with their dielectric strength. Such analysis is based on calculating energies of reactions for molecular ionization, dissociative ionization, parent negative ion formation, and dissociative electron attachment processes. We hypothesize that the estimation of the required energy for a reduced number of processes that take place in electrically stressed gases could be related to the gas’ capability to manage the electron flow during an electrical discharge. All calculations were done with semiempirical quantum chemistry methods, including an initial optimization of molecular geometry and heat of formation of the dielectric gases and all of species that appear during electron interaction reactions. The performance of semiempirical methods Austin model 1 and Parametric model 3 (PM3) was compared for several compounds, PM3 being superior in most cases. Calculations performed for a sample of nine dielectric gases show that electron attachment and detachment processes occur in different energy bands that do not overlap for any value of the dielectric strength. We have also analyzed the relationship between dielectric strength and two physical properties: electron affinity and ionization energy. Calculations performed for 43 dielectric gases show no clear correlation between them, although certain guidelines for the qualitative estimation of dielectric strength can still be assessed.

Article Outline

INTRODUCTION
METHODOLOGY
RESULTS AND DISCUSSIONS
1. Ionization energy and electron affinity
2. Main electron interactions in electrically stressed gases
CONCLUDING REMARKS

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KEYWORDS and PACS

Keywords

electric strength, ionisation, dissociation, discharges (electric), quantum chemistry, heat of formation, electron detachment, plasma collision processes, plasma dielectric properties

PACS

52.80.-s

Electric discharges
52.20.Fs

Electron collisions
52.20.Hv

Atomic, molecular, ion, and heavy-particle collisions
52.25.Mq

Dielectric properties
52.25.Jm

Ionization of plasmas

ARTICLE DATA

Digital Object Identifier

http://dx.doi.org/10.1063/1.2424532

PUBLICATION DATA

ISSN

0021-8979 (print)

1089-7550 (online)

Publisher

$abstract.society.value is a Member of CrossRef

American Institute of Physics

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