GB737289A - Improvements in or relating to electron discharge devices utilising travelling waves - Google Patents

Abstract

737,289. Travelling wave tubes; space charge wave tubes. WESTERN ELECTRIC CO., Inc. March 27, 1953 [April 1, 1952], No. 8531/53. Class 39 (1). A microwave discharge tube has a wave transmission circuit comprising a single ribbon helix, the wide dimension of the ribbon, which is parallel to the beam, being at least 0.8 of the helix pitch, and the circumference per turn of the helix being a plural odd number of free space half wavelengths at the design frequency of the tube. The circumference per turn is preferably three half wavelengths, in which case the above ratio is preferably exactly 0.8. For a larger circumference per turn, the ratio is greater than 0.8. The beam may interact with a fundamental or spatial harmonic wave. The helix may be formed by grooving a metal cylinder, the pitch of the groove being tapered at each end for impedance matching or by winding a ribbon in which case it is carried by spacer rods. The device is magnetically focused by solenoid 14, Fig. 1, and comprises copper envelope 11 supporting helix 15 from its inner surface; the beam is annular. In a modification, an annular beam may be projected outside and around the helix. Two short ribbon helices may be used as the input and output circuits in space charge wave amplifiers. Specifications 668,168 and 714,832 are referred to.