Improved Materials and Processes of Dispenser Cathodes.
Final rept. 1 Apr 80-1 Apr 84,
HUGHES AIRCRAFT CO TORRANCE CA ELECTRON DYNAMICS DIV
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Several process variables affecting the final electron emission properties of impregnated dispenser cathodes were investigated. In particular, the influence of billet porosity, impregnant composition and purity, and osmium-ruthenium coating were studied. Work function and cathode evaporation data were used to evaluate cathode performance and to formulate a model of cathode activation and emission. Results showed that sorted tungsten powder can be reproducibly fabricated into cathode billets. Billet porosity was observed to have the least effect on cathode performance. Use of the 411 aluminate mixture resulted in lower work functions than did use of the 532 mixture. Under similar drawout conditions, the coated cathodes showed superior emission relative to uncoated cathodes. In actural Pierce gun structures under accelerated life test, the influence of impregnant sulfur is clearly shown to reduce cathode performance.
- Electrical and Electronic Equipment