GB1084570A - Traveling-wave tubes - Google Patents

Abstract

1,084,570. Travelling wave tubes. RAYTHEON CO. Dec. 20, 1965 [Dec. 21, 1964], No. 53933/65. Heading H1D. A travelling wave tube having an-ion draining electrode extending along and parallel with the electron beam includes also a grid electrode, electrically insulated from the draining electrode and extending between the latter and the beam, to minimize the disturbance of the beam focusing by the draining electrode. In a backward wave oscillator in which a gun (Fig. 2, not shown) projects two beams along, and either side of, an ion draining electrode in the form of a strip 50, Fig. 4, extends along and adjacent the outer faoe of each beam 51, 58, each draining electrode being enclosed by, and spaced by a ceramic spacer 57, Fig. 4, from, a further electrode 53 having a grid of parallel bars 54 on the side facing the beam, the bar spacing being chosen to match that of the slow wave structure. The grid electrodes are held at the potential of the slow wave structure, and the draining electrodes preferably at cathode potential, the beams being focused by an external cylindrical magnet (10), Fig. 1 (not shown), and the output from the gun end of the slow wave structure being connected to the inner conductor (16) of a coaxial output line (14). The gun includes a cathode cylinder (26), Fig. 2 (not shown), which contains the emissive surface and a heater therefore, is supported by a ceramic plate (24), and has its end closed by a plate (30) having spaced rectangular apertures (31) and (32) to define the two electron beams, a further apertured plate (33) acting as accelerating electrode. Reference is also made to the use of the ion drain electrode/slow wave structure assembly in forward or backward wave M-type devices having toroidal slow wave structures and in linear magnetrons, and to the use of a ladder line rather than an interdigitated slow wave structure.