Electron-transport, ionization, attachment, and dissociation coefficients in SF/sub 6/ and its mixtures
An improved set of electron-collision cross sections is derived for SF/sub 6/ and used to calculate transport, ionization, attachment, and dissociation coefficients for pure SF/sub 6/ and mixtures of SF/sub 6/ with N/sub 2/, O/sub 2/, and Ne. The SF/sub 6/ cross sections differ from previously published sets primarily at very low and high electron energies. At energies below 0.03 eV the attachment cross section is adjusted to fit recent electron swarm experiments, while the elastic momentum transfer cross section is increased to the theoretical limit. At high energies an allowance is made for the excitation of highly excited levels as observed in electron beam experiments. The cross-section sets used for the admixed gases have previously been published. Electron kinetic energy distributions computed from numerical solutions of the electron-transport (Boltzmann) equation using the two-term, spherical harmonic expansion approximation were used to obtain electron-transport and reaction coefficients as functions of E/N and the fractional concentration of SF/sub 6/. Here E is the electric field strength and N is the gas number density. Attachment rate data for low concentrations of SF/sub 6/ in N/sub 2/ are used to test the attachment cross sections. Particular attention is given to the calculation of transport and reaction coefficients at the critical E/N = (E/N)/sub c/ at which the ionization and attachment rates are equal.
- Research Organization:
- Joint Institute for Laboratory Astrophysics, National Bureau of Standards and University of Colorado, Boulder, Colorado 80309
- OSTI ID:
- 6764485
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 64:9; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
BEAM TRANSPORT
BEAMS
BREAKDOWN
COLLISIONS
CROSS SECTIONS
DISPERSIONS
DISSOCIATION
ELECTRON BEAMS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
ENERGY RANGE
EV RANGE
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
GASES
HALIDES
HALOGEN COMPOUNDS
IONIZATION
LEPTON BEAMS
MIXTURES
MOLECULE COLLISIONS
MOMENTUM TRANSFER
NEON
NITROGEN
NONMETALS
OXYGEN
PARTICLE BEAMS
RARE GASES
SULFUR COMPOUNDS
SULFUR FLUORIDES