Drift field roehre with crossed electrical and magnetic fields,

摘要

1,024,922. Travelling-wave tubes. LITTON INDUSTRIES Inc. Nov. 27, 1963 [Nov. 30, 1962], No. 46869/63. Heading H1D. The collector of a crossed-field travelling wave tube comprises two or more collector electrodes arranged for selective collection of electrons according to their energy on entering the collector region. This prevents electrons arriving at the collector with a high kinetic energy, and hence reduces collector heating. In the forward wave amplifier shown a " depressed collector " electrode 20 is maintained at cathode voltage and the two collectors, 20 and 19, diverge to give a decreasing ratio of electric to magnetic fields in the beam direction and so deflect high energy electrons on to the " depressed " collector 20. Subsequently the two collectors converge, to deflect the remaining low energy electrons on to the conventional, slow-wave structure voltage collector 19. Deflection may alternatively be obtained by increasing the magnetic field along the collector. In an alternative embodiment, an abrupt change of distance is provided between the mutually facing electrode surfaces in the collector, producing a smooth continuity in the ratio of the electric to magnetic field strength. In a further embodiment, Fig. 9 (not shown), the depressed collector electrode is wedgeshaped and positioned adjacent a further electrode, maintained at the potential of the sole electrode. The position of the depressed collector 20, and hence the field strength in the collector, may be adjusted by a screw, diaphragm 34, and rod 29.