Theory of positive corona in SF sub 6 due to a voltage impulse

Journal Article · Mon Apr 01 00:00:00 EST 1991 · IEEE Transactions on Plasma Science (Institute of Electrical and Electronics Engineers); (United States)

DOI:https://doi.org/10.1109/27.106801· OSTI ID:5834843

Morrow, R ^[1]

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1. CSIRO, Div. of Applied Physics, Lindfield, NSW 2070 (AU)

This paper reports on a theoretical examination which is made of the mechanism of corona formation for a positive point-plane gap in SF{sub 6} at 100 kPa. The impulse voltage applied has a rise time of 15 ns and peak value of 200 kV. Seed electrons are released 1 ns after the start of the voltage rise. For a 0.5-cm diameter positive sphere located 6.5 cm from a negative plane, the calculated circuit current initially consists of subnanosecond corona onset pulses, and then the current steadily rises to a maximum, as the voltage reaches a maximum, followed by a rapid fall in current. During the current rise a streamer moves out into the gap along a 100-{mu}m channel, with the electric field in the streamer trail E {gt} E*, where E* is the critical field where ionization equals attachment. The light output during the discharge is predicted to be a maximum at the anode with only a minor pulse of light at the streamer head, making it hard to detect. After the current maximum, recombination rapidly reduces the numbers of positive ions, negative ions, and electrons, but the net charge density remains constant and thus so does the electric field. The electric field is E {approximately} E* in the streamer trail, but has a sharp maximum, E {much gt} E* at the head of the streamer trail. The origin of mid-gap precursors, observed when the streamer channel reilluminates after some 100 ns, is attributed to this field maximum in the remnant electric field. The evolution of positive ions, negative ions, and electrons is described by one-dimensional continuity equations, with the space-charge electric fields determined by the disk method. The effects of ionization, attachment, recombination, electron diffusion, and photoionization are all included.

• OSTI ID: 5834843
• Journal Information: IEEE Transactions on Plasma Science (Institute of Electrical and Electronics Engineers); (United States), Vol. 19:2; ISSN 0093-3813
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
SULFUR FLUORIDES
CORONA DISCHARGES
ANIONS
ANODES
CATIONS
CHARGE DENSITY
ELECTRIC FIELDS
ELECTRIC POTENTIAL
ELECTRONS
HIGH PRESSURE
IONIZATION
NUMERICAL SOLUTION
ONE-DIMENSIONAL CALCULATIONS
PRECURSOR
PULSES
RECOMBINATION
SPACE CHARGE
STREAMER SPARK CHAMBERS
CHARGED PARTICLES
ELECTRIC DISCHARGES
ELECTRODES
ELEMENTARY PARTICLES
FERMIONS
FLUORIDES
FLUORINE COMPOUNDS
GAS TRACK DETECTORS
HALIDES
HALOGEN COMPOUNDS
IONS
LEPTONS
MEASURING INSTRUMENTS
RADIATION DETECTORS
SPARK CHAMBERS
SULFUR COMPOUNDS
426000* - Engineering- Components
Electron Devices & Circuits- (1990-)
990200 - Mathematics & Computers