Evaluation of methods for increasing vacuum breakdown strength
Research to determine the effectiveness of coated and gas shielded cathodes as a means of increasing vacuum breakdown strength under short pulse conditions is reported. A technique for rapidly evaluating large numbers of coatings on small electrodes at relatively low pulse voltage (120 kV or less) and methods for testing larger electrodes and fewer coatings at higher total voltage were developed. Experiments with gas shielded cathodes were also conducted. Results suggest that it may be possible to eliminate prebreakdown current and to double breakdown strength by applying a suitable coating to the cathode. Breakdown stresses in excess of 2 MV/cm were obtained in a 0.5 mm gap with sputtered coatings of alumina, Cr/sub 2/O/sub 3/, and several readily available epoxies. Electrodes two orders of magnitude greater in area were tested, and stresses approaching 1 MV/cm were measured in 5 mm gaps for several epoxies and for alumina. It has further been shown that, because similar trends occurred in the data from large and small experiments, it should be possible to screen potential coatings rapidly and effectively with minimum expenditure using a method similar to that employed for small electrodes at low pulse voltage.
- Research Organization:
- Ion Physics Corp., Burlington, MA (USA); Massachusetts Inst. of Tech., Cambridge, MA (USA)
- Sponsoring Organization:
- US Energy Research and Development Administration (ERDA)
- DOE Contract Number:
- EY-76-C-02-4002
- OSTI ID:
- 7321205
- Report Number(s):
- COO-4002-3; TRN: 77-014651
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CATHODES
COATINGS
PERFORMANCE TESTING
DIELECTRIC MATERIALS
ALUMINIUM OXIDES
BARIUM COMPOUNDS
BREAKDOWN
CHROMIUM OXIDES
EPOXIDES
GASES
TITANIUM COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHROMIUM COMPOUNDS
ELECTRODES
FLUIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
TESTING
TRANSITION ELEMENT COMPOUNDS
420800* - Engineering- Electronic Circuits & Devices- (-1989)
420500 - Engineering- Materials Testing
700209 - Fusion Power Plant Technology- Component Development & Materials Testing