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An investigation of radial recovery of a high current spark channel

University of British Columbia

Reignition curves have been obtained for a high current (40ka) spark gap channel in air at atmospheric pressure at various radial distances down to delay times of 50 µs. after initiation of spark. The reignition curves in the ‘thermal breakdown' regime are obtained by a constant voltage generator having a variable output ranging from 100 volts to 2.5 kv, while those in the 'spark breakdown' regime are obtained by the use of a restriking voltage generator having a higher voltage output ranging from 1 kv to 15 kv. The experimental results show that the gas at large radial distances recovers faster than that at a smaller distance. A special feature of the recovery curves is the occurrence of a dip which is thought to be the effect of a thermal wave. Gas temperatures are derived by using the equation of state, Paschen curves and the reignition measurements. A temperature profile of the spark channel has been obtained which indicates that the spark channel has a fairly uniform temperature up to a radial distance of 2.5 cm. Beyond this distance the temperature drops rapidly to ambient temperature at a radial distance of 4 cm, Deionization and recovery mechanisms are predicted theoretically and are verified during the earlier recovery period in which 'thermal breakdown' occurs and during the later recovery period when 'spark breakdown' is observed.

Text

2011-09-23

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http://hdl.handle.net/2429/37590

Physics

University of British Columbia

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