GB1281666A - Microwave apparatus with tuning plunger - Google Patents

Abstract

1281666 Klystrons; cavity resonators VARIAN ASSOCIATES 19 April 1971 [16 March 1970] 26244/71 Headings H1D and H1W A tuning plunger for a hollow microwave structure is provided with sliding contactors constituted by a plurality of resiliently compressible, electrically conductive, loops generally disposed in planes parallel to the direction of movement of the plunger, each loop being fixed to the plunger along a portion which faces into the microwave cavity, but being free to move relative to the plunger along a diametrically opposed portion which faces out of the microwave structure. A klystron cavity 12 is tuned by a plunegr 15, which is connected to the end of the cavity by an airtight bellows 16, and which has brazed to its end a yoke 45 having sapphire bearings 46 dimensioned to provide a slight clearance with the inside narrow walls 21 and 22 of the cavity, and a copper faceplate 47. A helically grooved rod 33 having flats ground at 34 and 45 is fixed at its ends to the yoke 45, and has a tungsten wire 38 wound into the grooves on the line cylindrical portions 36 and 37 of the rod to form a distorted helix the loops of which are compressed to provide firm engagement with the broad walls 18 and 19, and the lands between the grooves at the leading edge 36 of the rod being peened over the wire. Capacitive tuning arms may project from the faceplate 47 to increase the tuning range. The yoke 45 may include a coolant channel; the trailing edge 37 of the rod may be brazed to the yoke 45 to increase cooling; and the cavity brood walls may be provided with relieved portions 49, Fig. 2, into which the tuning assembly may be retracted during bake-out of the tube, to prevent annealing out of the spring action of the helix. The wire 38 may be formed into the distorted helix shape shown by the use during winding of shaped aluminium inserts keyed into slots 42 and 43, the aluminium being subsequently removed by a chemical etch.