GB798932A - Improvements in travelling wave tubes - Google Patents

Abstract

798,932. Travelling wave tubes. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Jan. 3, 1956 [Jan. 11, 1955], No. 181/56. Class 39(1). A travelling wave tube amplifier has a delay line which has delay characteristics in two mutually perpendicular directions, a standing wave being set up in at least one of these directions and a travelling wave in the other direction, one or more electron beams travelling parallel to the structure in the direction of the first mentioned standing wave, and means, preferably straps are provided to produce a constant phase shift of # or a fraction thereof between any two adjacent travelling wave channels. In one form, Fig. 1, reflectors R, R 1 cause standing waves to be set up in the OY direction along which one or more electron beams pass. The phase shift between the ends of each OY delay line is K# where K is any integer, e.g., # and the beam velocity is synchronized with a spatial harmonic component of the travelling component of the standing wave. Alternate and intermediate elements in the OY direction are strapped by straps 6a, b, 8a, b (to give the # mode) and have bifilar input and output feeders 20, 21 the two conductors of each line carrying energy in phase opposition. In another form, Fig. 2, the delay line comprises multiapertured discs supporting standing waves around their circumference and an axial travelling wave. The electrons emitted by axial cathode 12 are bent into circular paths by axial magnetic field 16. The bifilar input and output 5, 7, feeder lines are connected to straps 6, 8. Since the device is not directional, oscillations must be prevented by directive loss, e.g., magnetically biased ferrite disposed on the first few or last few multiapertured discs, Fig. 3 (not shown). The metal envelope has insulating end caps to support the axial cathode which contains heater filament leads 15. Specification 798,931 is referred to.