GB531541A - Improvements in electron multipliers - Google Patents

Abstract

531,541. Electron multipliers. BOSCH, F. J. G. VAN DEN., and VACUUM-SCIENCE PRODUCTS, Ltd. May 11, 1939, Nos. 14124 and 15349. [Class 39 (i)] In electron multipliers, the secondary electron emitting cathodes are each associated with an apertured electrode spaced therefrom in the direction of approach of the primary electrons and at the same or substantially the same potential for the purpose of screening the intervening space from the field of the preceding cathode. The invention may be applied to multipliers of the type comprising successive secondary cathodes in a plane, or the type in which the secondary cathodes are disposed in two parallel groups arranged parallel and in staggered formation, but is described, as shown in Fig. 1, in connection with the type comprising a succession of apertured cathodes 15, followed by an apertured collecting anode 17, and a solid secondary emitting cathode 16. The source of primary electrons is a thermionic cathode 11, heated by a filament 12, and followed by a control grid 13 and accelerating electrode 14. The auxiliary electrodes 20 disposed in front of the cathodes 15 consists of a grid of very fine wires and are preferably mechanically and electrically connected to their associated cathodes mid-way between the successive cathodes. In the arrangement shown in Fig. 4, the secondary cathodes 15 are of the kind described in Specifications 516,621 and 516,664, the conical apertures 18 in successive cathodes being staggered relatively to one another. The auxiliary electrodes 20 are apertured plates of the same kind, and are arranged so that the apertures are in line with those of the preceding cathode. In a modification, control grids may be disposed in the spaces between the cathodes and their associated electrodes and may have modulating or control potentials applied thereto. A circuit arrangement for applying the potentials to the several electrodes and the input and output circuits, is shown in Fig. 1.