Dielectric properties for SF/sub 6/ and SF/sub 6/ mixtures predicted from basic data
We have calculated ..cap alpha.. and eta, the ionization and attachment coefficients, and (E/N) *, the limiting breakdown electric-field--to--gas-density ratio, in SF/sub 6/ and SF/sub 6/ mixtures by numerically solving the Boltzmann equation for the electron energy distribution. The calculations require a knowledge of several electron collision cross sections. Published momentum transfer and ionization cross sections for SF/sub 6/ were used. We measured various attachment cross sections for SF/sub 6/ using electron-beam techniques with mass spectrometric ion detection. We determined a total cross section for electronic excitation of SF/sub 6/ by comparing the predicted values of ..cap alpha.., eta, and (E/N) * with our measured values obtained from spatial current growth experiments in SF/sub 6/ in uniform fields over an extended range of E/N. With this self-consistent set of SF/sub 6/ cross sections, together with published He and N/sub 2/ cross sections, it was then possible to predict the dielectric properties of SF/sub 6/-He and SF/sub 6/-N/sub 2/ mixtures. Published experimental values of ..cap alpha.. for the SF/sub 6/-He mixtures lie between the values of ..cap alpha.. calculated with and without ionization of SF/sub 6/ by excited He atoms. Published experimental values of (E/N) * agree with our calculations to within 5% in both the SF/sub 6/-He and the SF/sub 6/-N/sub 2/ mixtures.
- Research Organization:
- Westinghouse RandD Center, Pittsburgh, Pennsylvania 15235
- OSTI ID:
- 5777413
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 50:11; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360106* -- Metals & Alloys-- Radiation Effects
ABLATION
ALUMINIUM
ELECTROMAGNETIC RADIATION
ELEMENTS
FOILS
IONIZING RADIATIONS
LASER RADIATION
LASERS
LINEAR MOMENTUM
LONGITUDINAL MOMENTUM
MEASURING INSTRUMENTS
METALS
NEODYMIUM LASERS
PHOTODIODES
PHYSICAL RADIATION EFFECTS
PULSES
RADIATION EFFECTS
RADIATIONS
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SOLID STATE LASERS
SPECTROMETERS
X RADIATION