Electric strength of metal-ceramic brazed units of thermionic energy converters in caesium vapours

The electric strength characteristics of the hollow metal-ceramic brazed units of thermionic energy converters have been investigated. The insulators was polycrystalline aluminum oxide of length l=10-50 mm, and measurements were made at temperature T=450-750 degrees C and the caesium vapor pressure P/sub Cs/=10/sup -1/-10/sup 3/ Pa. The experimental dependences of the breakdown voltage of the brazed units on the temperature, the parameter P/sub Cs/*l, and the value of the surface electric resistance of the insulators are given as well as the empirical equations obtained from the experimental data for calculating the breakdown voltage. A mechanism explaining the influence of the ceramic insulator on the electric strength characteristics of the caesium gap has been investigated. A breakdown model that includes this influence is proposed.<
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