Title :
Fast- and super-fast-warm-up cathodes using novel APG/APBN heaters
Author :
Cattelino, M.J. ; Miram, G.V. ; Smith, Bernard
Author_Institution :
Varian Associates Inc., Palo Alto, CA, USA
fDate :
10/1/1991 12:00:00 AM
Abstract :
A fast-warm-up heater/cathode approach for microwave tubes is described. Anisotropic pyrolytic graphite (APG) deposited onto anisotropic pyrolytic boron nitride (APBN) was used to fabricate heater wafers. Both planar and spherical heaters can be produced. APG/APBN characteristics are discussed along with methods for heater fabrication. Measured fast-warm-up thermal cycling data are presented for 4 to 60 mm cathode diameters. Fast warm-up times of 1-2 s for 4.0-6.4-mm-diameter cathodes and less than 20 s for 60-mm-diameter cathodes were demonstrated with highly reliable thermal cycling performance
Keywords :
microwave tubes; thermionic cathodes; 1 to 20 s; 4 to 60 mm; APG/APBN heaters; C-BN; anisotropic pyrolytic graphite; anisotropic pyrolytic nitride; cathodes; fast-warm-up thermal cycling data; heater fabrication; heater wafers; microwave tubes; spherical heaters; super-fast-warm-up; Anisotropic magnetoresistance; Boron; Cathodes; Coatings; Electromagnetic heating; Fabrication; Impedance; Magnetic fields; Thermal conductivity; Wire;
Journal_Title :
Electron Devices, IEEE Transactions on
