The Hollow Cathode Phase of Pseudospark Operation
Abstract
Reported here are results of a collaborative theoretical and experimental effort to develop useful predictive models of the hollow cathode processes that occur in the pseudospark and back-lighted thyratron. During pulsed operation there are several sequential modes of cathode behavior. High current (~2-100 kA) transport occurs during a highly emissive, or super-emissive mode of cathode operation (Phys. Rev. Lett. 60 (23), 2371 (1988)). Prior to this mode a hollow cathode mode occurs that is an essential step leading to the super-emissive mode. This hollow cathode discharge is also a source of an intense, high-brightness electron beam. In results presented here the electron beam is shown to be a consequence of the plasma cathode produced by hollow cathode ionizational processes, and the high electric field which is required to initiate high current conduction at the next phase of discharge is predicted from the simulation. Experimental results of a hydrogen hollow cathode discharge electron beam are also presented. An electron beam with pulse-length of 10's n secs, peak beam current of 170 A, efficiency of 21% was measured at -20 kV applied voltage. The model is shown to be in good qualitative agreement with experiments. It is remarkable that these emission processes can be modeled at a microscopic level not possible for most technologically relevant cathodes. Based on a microscopic description of collisional, dissociative and ionizational processes, the model can predict transport and electron beam parameters including emittance and brightness.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1993
- Accession Number
- ADA640385
Entities
People
- J. P. Boeuf
- L. Pitchford
- Martin A. Gundersen
- R. Liou
- V. Puech
Organizations
- University of Southern California