Calculations of Electrical Breakdown in Air at Near-Atmospheric Pressure
1965; American Institute of Physics; Volume: 138; Issue: 5A Linguagem: Inglês
10.1103/physrev.138.a1357
ISSN1536-6065
Autores Tópico(s)High voltage insulation and dielectric phenomena
ResumoA computer program based on the Townsend avalanche model, but explicitly including space charge, has been used to calculate electrical breakdown in air at near-atmospheric pressure. A good fit to Bandel's experimental temporal-current-growth curves may be obtained by using a secondary ionization coefficient that includes 10% ion and 90% photon portions. Only a poorer fit could be obtained when using a 100% photon effect, with either a fixed photon delay independent of overvoltage or a constant reduced electron mobility to simulate an attachment-detachment process. The same agreement and disagreement, respectively, were obtained by comparison of the results of calculations with the breakdown-time-versus-overvoltage measurements of Fisher and Bederson. The effect of variations of the number of initiating electrons from the cathode and of the approach voltage is detailed. The calculations indicate that a luminous front propagates from the anode to the cathode at a velocity of up to \ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}${10}^{7}$ cm/sec in the final calculable stages of breakdown.
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