Negative ion formation in SF/sub 6/ spark by-products
When sulfur hexafluoride (SF/sub 6/) gas is used as electrical insulation (e.g., in high voltage or switching applications), deterioration of the gas caused by sparks, corona, high electrical stress, or high temperature results in a buildup of by-products whose electron attaching properties differ from those of SF/sub 6/. We have identified a number of long-lived by-products formed by spark discharges in SF/sub 6/ at pressures in the range 40 to 233 kPa and measured quantitatively the concentrations of the by-products SOF/sub 2/, SO/sub 2/F/sub 2/, SO/sub 2/, SiF/sub 4/, and SOF/sub 4/. These by-products are formed via the interaction of the multiplicity of transient short-lived species in sparked SF/sub 6/ with moisture, electrode material, and insulators. Each has been studied individually in a time-of-flight mass spectrometer, and the negative ion yields as a function of electron energy in the range 0 to 12 eV have been measured and are reported. The negative ions and their peak energy positions (shown in parentheses in eV) are: F/sup -/ (0.6), SOF/sub 2//sup -/* (approx. 0) for SOF/sub 2/; F/sup -/ (3.45), F/sub 2//sup -/ (3.3), SO/sub 2/F/sup -/ (2.95), SO/sub 2/F/sub 2//sup -/* (approx. 0) for SO/sub 2/F/sub 2/; O/sup -/ (4.55), S/sup -/ (4.0), SO/sup -/ (4.8) for SO/sub 2/; F/sup -/ (11.25), SiF/sub 3//sup -/ (11.1) for SiF/sub 4/; and F/sup -/ (3.3), SOF/sub 3//sup -/ (approx. 0) for SOF/sub 4/ (the asterisk (*) indicates that the ion is long lived (lifetime >10/sup -6/ s) with respect to autodetachment). Cross sections for electron attachment to SO/sub 2/ are reported and compared with literature data.
- Research Organization:
- Oak Ridge National Lab., TN (USA); Tennessee Univ., Knoxville (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6970612
- Report Number(s):
- CONF-840403-6; ON: DE84012340
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360304* -- Composite Materials-- Physical Properties-- (-1987)
ANIONS
CHARGED PARTICLES
CROSS SECTIONS
DIELECTRIC MATERIALS
ELECTRIC DISCHARGES
ELECTRIC SPARKS
ELECTRICAL INSULATION
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
IONS
MATERIALS
PHYSICAL PROPERTIES
SULFUR COMPOUNDS
SULFUR FLUORIDES