GB1469199A - Electron beam amplifier tube with mismatched circuit sever - Google Patents

Abstract

1469199 Travelling-wave tubes VARIAN ASSOCIATES 29 Oct 1975 [4 Nov 1974] 44612/75 Heading H1D The efficiency of an electron beam amplifier tube having an isolated slow-wave structure output section, e.g. a severed travelling-wave tube or a hybrid tube, is increased by reflecting towards the output a substantial portion of the wave energy flowing on the slow-wave structure towards its upstream end. The output section of a hybrid tube shown in Fig. 2 consists of a clover-leaf slow-wave structure 40, impedance matched at its output end via an iris 44 to an output waveguide 45 (and Fig. 1, not shown), the upstream end cavity 60 being coupled to a waveguide 62 having a matched load termination 64 and a capacitive iris 63 the height and position of which determine the amplitude and phase of the wave reflected towards the output of the tube. Alternatively, the waveguide 62 may be short-circuited at its termination (65, Fig. 4, not shown), an attenuator (66) being mounted, if required, in the end cavity 60 of the slow-wave structure. In a further arrangement (Fig. 5, not shown), the waveguide 62 is terminated in a matched load, the amplitude of the reflected wave being determined by the iris coupling (61<SP>1</SP>) between the final cavity 60 and the waveguide, and the phase being determined by choosing the geometrical dimensions of cavity 60 to give a resonant frequency different from that of the other cavities. In a further arrangement (Fig. 6, not shown), both the amplitude and phase of the reflected wave is determined by the geometry of the final cavity 60, the waveguide 62 being dispensed with. Fig. 7 shows a crossed-fleld amplifier having a slow-wave severed at 78, the final section 77 being provided at its upstream end with waveguide section 82 incorporating wave reflecting obstacle 83 and matched load 84.