Evidence for large-area superemission into a high-current glow discharge

Hartmann, W.; Dominic, V.; Kirkman, G. F.; Gundersen, M. A.
October 1988
Applied Physics Letters;10/31/1988, Vol. 53 Issue 18, p1699
Academic Journal
This letter presents evidence for large-area (≊1 cm2) cathode superemission (∼10 000 A/cm2) into a high-current glow discharge in a pseudospark or back lighted thyratron switch. Cathodes studied with a scannning electron microscope following operation at 6–8 kA, ≊1 μs pulse length, and 105 pulses in a low-pressure H2 discharge show evidence of melting of a thin surface layer within a radius of ∼4 mm, indicating that the discharge is a superdense glow with a cross-sectional area of the order of 1 cm2, rather than an arc. Further supporting evidence is provided by streak camera data. An ion beam present during the avalanche phase of the discharge is responsible for heating the cathode surface resulting in a significant field-enhanced thermionic emission.


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