GB780107A - Improvements in or relating to delay lines - Google Patents

Abstract

780,107. Travelling wave tubes. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. July 18, 1955 [July 16, 1954], No. 20790/55. Class 39(1). In a travelling wave tube the delay line comprises a conductive helix and a conductive comb at least some of the turns of the helix being directly connected to at least some of the teeth of the comb. In one form, Fig. 1, the helix turns 11 are brazed to the comb teeth 12 or the structure could be formed out of a solid block. The helix may be circular, or flattened, Figs. 4, 5 (not shown), or the comb fingers may be curved, Fig. 6 (not shown). In another form, Fig. 7, a capacitive strip 14, near the comb fingers acts as a back plate ; its position can be mechanically adjusted from outside the tube wall. If desired the strip 14 can be coated with loss material or part or the whole of the comb can be coated with loss material from a spray gun. In another form, Fig. 9 (not shown) cooling fluid is circulated in helix 11 and/or within the base of the comb or within the base and/or the fingers of the comb. The comb may, however, cool the helix merely by conduction. Instead of equal numbers of helix turns and comb teeth all connected together, there may be n times as many comb teeth as helix turns or n times as many helix turns as comb teeth. The helix turns may for example be connected in pairs or threes to comb teeth. If there are more teeth than turns, all turns are connected to teeth, but not all teeth are connected to turns. The travelling wave tube, an example of which is discussed with reference to Fig. 10 (not shown) may or may not operate with crossed electric and magnetic fields. The device is designed for wide band operation in the forward fundamental mode. Specification 743,519 is referred to.