GB946020A - Improvements in or relating to travelling wave tubes - Google Patents

Abstract

946,020. Travelling wave tubes. STANDARD TELEPHONES & CABLES Ltd- May 18, 1962, No. 19270/62. Heading H1D. In a unitary assembly of a periodic magnetic focusing arrangement for a travelling wave tube and of an electromagnetic wave transducer (waveguide or cavity resonator) affording means for radio frequency coupling to the slow wave structure of the travelling wave tube, the transducer interrupting the magnet system of the magnetic focusing arrangement over an axial length longer than a half period thereof, a magnetic polepiece in the form of a thin metal strip of width less than half a guide wavelength and having an aperture for insertion therethrough of the travelling wave tube is mounted within the transducer and extends transversely across the longitudinal axis of the assembly. The width of the transducer may be ¢, ¥ or a full period. The polepiece within the transducer may be plated with noble metal. In one form, Fig. 3, using a waveguide transducer 12 is the internal polepiece and 8 are softer iron polepieces let into the waveguide walls and co-operate with permanent magnets 2, 2<SP>1</SP> or with solenoids. The width of the metal strip polepiece 12 is less than half a guide wavelength. The polepiece 12 is rectangular or tapered. In Fig. 6, 15 is the cavity resonator transducer and 12 the internal polepiece. 16 is a coaxial line feeder. The travelling wave tube has a helix delay line and the input and output waveguides have impedance matching plungers.