Observations of a mode transition in a hydrogen hollow cathode discharge using phase resolved optical emission spectroscopy

Sam Dixon, Christine Charles, James Dedrick, Timo Gans, Deborah O'Connell, Rod Boswell

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Two distinct operational modes are observed in a radio frequency (rf) low pressure hydrogen hollow cathode discharge. The mode transition is characterised by a change in total light emission and differing expansion structures. An intensified CCD camera is used to make phase resolved images of Balmer α emission from the discharge. The low emission mode is consistent with a typical γ discharge, and appears to be driven by secondary electrons ejected from the cathode surface. The bright mode displays characteristics common to an inductive discharge, including increased optical emission, power factor, and temperature of the H2 gas. The bright mode precipitates the formation of a stationary shock in the expansion, observed as a dark region adjacent to the source-chamber interface.
Original languageEnglish
Article number014104
Number of pages4
JournalApplied Physics Letters
Issue number1
Publication statusPublished - 7 Jul 2014

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