Abstract: In a travelling-wave tube (20), a cylindrically-shaped slow-wave circuit cavity-defining member (34) is supported by and is thermomechanically bonded to a tubularly-configured vacuum wall member (32). The bonded joint comprises a pair of arcuate grooves (52) extending lengthwise of the slow-wave circuit and positioned diametrically opposite one another about the axis of the tube. A helical or wavy spring (54, 58) lies in each groove and is resiliently biased in intimate mechanical and thermal contact between the groove and the vacuum wall. The helical spring, in particular, can be used as a conduit for exhaust of gases from the travelling-wave tube during its fabrication.

Abstract: The disclosed multipactor device has a waveguide bandpass filter structure including a plurality of spaced pairs of opposing electrodes defining respective gaps therebetween in which multipactor action can occur in response to input microwave power in excess of a predetermined level. A radioactive source of beta particles provides electrons within the bandpass filter structure to ensure a very rapid commencement of multipactor action. The radioactive source includes a disk coated with a tritium compound and mounted in a transverse bore adjacent to the bandpass filter structure.

Abstract: The specification describes a vacuum device utilizing the multipacting phenomenon in a special insulated-electrode microwave comb-line structure and functioning as a high speed, single pole, single throw, RF switch with the exception that in the off condition, power is absorbed in the device.