| 摘要 |
1,038,258. Transit-time tubes; electron multiplier tubes; cathode-ray tubes. STANDARD TELEPHONES & CABLES Ltd. April 17, 1964 [April 19, 1963], No. 15987/64. Heading H1D. An electron discharge device has bunches of electrons which form a beam generated by multipacting between secondary electron emissive surfaces forming part of a cavity resonator, electromagnetic energy being imparted to an electromagnetic field in a further cavity resonator. In one form, Fig. 2, the bunches are formed by multipacting between two curved secondary electron emissive surfaces 23, 24 which forms the end faces of a re-entrant resonator 4, Fig. 1 (not shown), a central aperture in one surface allowing annular bunches of electrons to be accelerated through a hollow cylinder 26, Fig. 1 (not shown), acting as an anode towards a further resonator. In another form, Fig. 7, the electron emissive surfaces 39, 43 are coaxially disposed around the tube axis, one, 39, being formed on the re-entrant portion of the resonator which extends through an aperture in the opposite end face, the relatively large diameter electron rings formed being electrostatically focused to a smaller diameter before they are incident upon a gap in a second resonator. Both cavities may be tuned by a differential screw and flexible bellows arrangement. Multipacting between the emissive surfaces is obtained by making the transit time between the surfaces equal to an odd number of half the period of the R.F. field applied to the cavity; this produces phase-focusing in which the time of arrival of electrons at the surfaces becomes closely synchronized after several transists. The annular bunches of electrons are emitted from the gap by a combination of space charge forces, applied anode field penetrating the gap, and the geometrical shape of the surfaces. |
