CERAMIC RECEIVING TUBE REFINEMENT PROGRAM
Abstract
Some of the materials and processing problems associated with the development and operation of ceramic vacuum tubes were investigated experimentally. The tubes were designed for operation where superior performance is required at ambient temperatures as high as 500 C. The following problems were investigated: cathode emission, vacuum seal, grid material, getter material and ceramic outgassing. Loss of emission from the oxide cathode is not a direct cause of tube failure as long as the cathode is processed carefully. A hot oxidizing atmosphere causes extensive oxidation of the seal elements. At ambient temperatures in excess of 400 C, seals begin to leak after a few hundred hours, but this failure cannot be attributed to oxidation alone. Gold grids inhibit adverse grid emission when exposed to hot oxide cathodes for grid temperatures up to 600 C. CerAlloy 400 operated at 500 C is an effective getter for the gases encountered in ceramic tubes. Heat treatment of ceramic under high vacuum causes the evolution of carbon monoxide, hydrogen, methane and water vapor. Heating to 1000 C effectively reduces the outgassing rate of the ceramic. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1961
- Accession Number
- AD0270582
Entities
People
- Bruce E. Barnaby