Electron discharge devices and molybdenum slow wave structures, the molybdenum slow wave structures having grain alignment transverse to the electron path

摘要

1,015,816. Making waveguides; bending; brazing. VARIAN ASSOCIATES. Nov. 14, 1963 [Dec. 17, 1962], No. 45077/63. Headings B3A, B3E and B3R. [Also in Division H1] In forming a slow wave structure for a travelling-wave tube a strip of molybdenum 23 having a transverse grain structure with respect to its longitudinal axis is passed through a stamping die assembly 24, 25, Fig. 2, to remove preselected portions 26, 27. The resulting structure is bent to U-shape in a forming die assembly 28, 29, Fig. 3, and then to cylindrical shape in a forming die assembly 31, 32, Fig. 4. The cylindrical structure is placed on a mandrel 37 in a firing jig, Fig. 5, comprising halves 36 secured together by screws 38 and fired in a hydrogen furnace to produce a stress relieved structure which is transferred to a brazing jig 39, Fig. 6, and a brazing mixture 40 applied to the portions to be joined, brazing being effected in a hydrogen furnace. Other materials such as copper, stainless steel, titanium or columbium may be used to produce " ring and bar " structures or other slow-wave structures, e.g. contrawound helices or structures of rectangular crosssection. With a material other than molybdenum the stress relieving step may be omitted. Instead of performing the initial operation of removing preselected portions of the strip by stamping or punching, this operation may be performed by discharge treatment or by etching. The cylindrical configuration may alternatively be obtained using a cam die assembly, and the brazing step may be omitted to produce slotted structures.