Abstract: A PPM coupled-cavity traveling wave tube has an RF structure comprising a re-entrant double-staggered ladder circuit. Several cavities are separated by iron pole pieces with penetrating slots to provide RF coupling between the cavities. Re-entrant copper bars are attached to both sides of the pole pieces that define the boundaries between adjacent pairs of cavities. These bars extend diametrically across the cavity interior around beam drift tubes The re-entrant bars on adjacent pole pieces are rotated relative to each other by 90 degrees about the beam axis. The bars are hollow along their length, and thereby provide channels for coolant flow around the drift tubes. These channels communicate through apertures with coolant distribution channels in the outer cavity walls extending along the length of the traveling-wave tube.

Abstract: The collector in a linear-beam electron tube is insulated from its heat sink so that it can be operated at a depressed potential. The insulation comprises two bands of dielectric sequentially in contact between the collector and heat sink. The intervening space is sealed off and preferably filled with a dielectric fluid to improve heat transfer and inhibit voltage breakdown. Gaps in one band are preferably aligned with solid parts of the other to reduce electric leakage.

Abstract: A slow-wave circuit for a TWT has periodic transverse plates extending across the axial by extending vacuum envelope. An opposed pair of apertures 24, 26 in each plate 20 couple adjacent cavities 28 between plates 20. Coupling apertures 24 in alternate plates 20 are rotated transverse to apertures 26 in the other plates to provide coupling only between adjacent cavities 28. Each plate 20 has transverse ridges 30 enclosing its axial beam aperture 22. The ridges 30 are orthogonal to the coupling apertures 24, 26 to increase beam coupling and decrease capacitance for wider bandwidth and higher impedance.

Abstract: A double-coupled ladder circuit for a traveling-wave tube has been a slow-wave circuit formed of a pair of combs, each cut from a single piece of metal. Transverse grooves are cut in each piece to form teeth and axial grooves are cut in the ends of the teeth. The two combs are joined at teeth ends to form a ladder with the transverse grooves aligned to form cavities and the axial grooves aligned to form a beam passageway. Coupling apertures are cut in both sides of a first set of alternating ladder rungs and a second set of apertures cut in the comb backing members over the second, interleaved, set of rungs. Thus, each cavity is coupled on two opposite sides to its preceding cavity and on the two remaining sides to its following cavity. The double coupling provides increased bandwidth and efficiency. Finally, side plates are affixed to cover the apertures, complete the cavity walls and form the vacuum envelope.

Abstract: A coupled-cavity slow-wave circuit for a millimeter-wave TWT is formed by forming cavities through a metallic bar or half-cavities in a pair of comb-shaped bars. The ends of the cavities are covered by cover members, one of which has a longitudinal groove to form "in line" coupling apertures between cavities.

Abstract: A traveling-wave amplifier tube adapted for use as a booster of transmitted signals has very small internal circuit attenuation so that it may be used without an electron beam as a transparent, passive path for low transmitter power. When the booster tube's beam is excited, the signal is amplified about 10dB. Upper bandedge instabilities in the lossless tube are inhibited by a lower cutoff frequency of the circuit near the output end than near the input end, so that bandedge power can flow both ways out of the large-signal output end.