| 摘要 |
1,074,449. Velocity-modulated tubes; electrode materials. SFD LABORATORIES Inc. Oct. 12, 1965 [Oct 26, 1964], No. 43279/65. Heading H1D. A toroidal, helix-derived, slow wave structure is constructed by forming a toroidal tube, of rectangular cross-section, by welding endplates 2 to the two ends of a pair of coaxial, coterminous cylinders 3 and 4, radially slotting the tube through its inner and two end walls, and finally forming a corresponding series of axial slots 7 in the outer wall, inclined at an angle such as to interconnect adjacent radial slots, the portion 6 being left unslotted to define the ends of the structure. A modified form in which the outer and the end walls are curved is also referred to. The structure, which may be of molydenum, copper, aluminium, or stainless steel, may be employed in an M-type device (Figs. 6 and 7, not shown), wherein it is mounted between electrically insulating, thermally conductive annuli 23 of boron nitride or beryllium oxide within a copper envelope 21, 22. The coaxially mounted, secondary emissive cathode 26-of beryllium/copper or aluminiumis in the form of a hollow cylinder enclosing a magnet 29 having polepieces 28 which also act as cathode end hats and produce an axial magnetic field in the interaction space 27. The cathode-magnet assembly is supported by an axial cathode lead 32, with respect to which the envelope and slow wave structure are maintained at a high D.C. potential. The tube may be employed as a forward wave amplifier, when the slow wave circuit is provided with input and output coaxial lines, e.g. 25; alternatively, it may be used as a noise generator, in which case the tube is filled with hydrogen, argon, or xenon at 10<SP>-1</SP> torr, and the input coaxial line is either dispensed with or, if present, terminated in a matched resistive load. A separate thermionic emitter may be employed as electron source, instead of the secondary emissive electrode 26. |
