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Investigations of the glow phase in high pressure spark discharges

University of British Columbia

The glow phase of high pressure spark discharges initiated by the Townsend mechanism of breakdown in hydrogen, nitrogen and carbon dioxide is studied using 16 ohm coaxial cable discharge techniques. Before the establishment of the spark channel in these low over-voltaged spark discharges, there exist two distinct transition stages, namely, a diffuse glow phase and a filamentary glow-to-channel transition phase. The optical appearance of the diffuse glow is similar to that of a normal d.c. glow discharge. It consists of a negative glow, a Faraday dark space, and a positive column. From our experimental results it is concluded that for the glow phase the cathode fall voltage and the ratio of the axial potential gradient to the gas pressure in the positive column are fixed for each gas. These values are independent of the impedance of the external circuit and the gas pressure. Comparisons with low pressure d.c. glow discharges indicate further that the cathode fall voltages are in agreement in both types of glow for the gases' investigated. In addition, a qualitative discussion about the transition nature of this diffuse glow phase is given on the basis of results obtained from spectroscopic investigations.

Text

2011-04-29

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http://hdl.handle.net/2429/34155

Physics

University of British Columbia

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