GB730687A - Improvements in delay lines having an interdigital structure, for travelling-wave tubes - Google Patents

Abstract

730,687. Travelling-wave tubes. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. April 2, 1953 [April 3, 1952], No. 9189/53. Class 39 (1). [Also in Group XL (b)] The delay line in a travelling-wave tube is constituted by inwardly curving interdigitating fingers 8, 9 fixed to a longitudinal bar 7, the electron beam passing within the space enclosed by the fingers. The fingers may be formed by bending over straight fingers attached alternately to either side of the bar, or by securing to the bar identical rings, the rings being split alternately on opposite sides of the bar. They may be formed by securing the bar along a helix and splitting the convolutions on alternate sides of the bar, or by the direct machining of the bar. The fingers may enclose a space of circular, oval or rectangular cross-section. The fingers themselves may be of circular, rectangular, or triangular cross-section. The fingers may be extended by straight portions 10, Fig. 7, extending along the flanks of the bar 7. A quarter-wave slot may be formed in the bar, the slot opening into the space enclosed by the fingers. Transverse slots may be formed between the fingers. The electron beam may completely encompass and diffuse about the conductors of the line. The beam may pass between an inner conductor and the line. The envelope of the tube may be of metal or it may be metallized or coated with graphite, or an outer conductor may be provided outside the envelope, for example by the support of a magnetic focusing device. Air or water cooling ducts may be formed in the bar. Preferably the bar is mounted in the tube against the envelope to aid the dissipation of heat. The fingers of the delay line nearest the electron gun are preferably made of refractory metal. Specification 699,893 is referred to.