GB463514A - Improvements in electron multipliers - Google Patents

Abstract

463,514. Electron multipliers. FARNSWORTH TELEVISION, Inc. May 1, 1936, No. 12396. Convention date, May 7, 1935. [Class 39 (i)] An electron multiplier for use as an oscillation generator or for amplifying electrons produced by thermionic or photo-electric means consists of two perforated plates A, B which act as the impact electrodes and are backed by collector plates 5 attached to leads 10. A central anode consists of a spiral 4. The plates A, B, are preferably of silver, oxidized and then caesium coated. The plates 5 are preferably of carbonized nickel to prevent secondary emission but they may be of tantalum, tungsten or molybdenum. The leads 10 are connected to a tuned circuit consisting of the adjustable condenser 16 and inductance 17 earthed at its mid point ; the anode is biassed by a battery 20. Electrons striking the solid part of the perforated plates cause secondary emission, the secondary electrons passing in a cloud between the two plates A, B ; electro-static or electromagnetic control cause longitudinal displacement of the electrons forming the cloud. Some electrons pass through the apertures and are collected by the plates 5, the distance from plates A, B to the plates 5 and the biassing being arranged that the current produced on the plates 5 will be at 180‹ to the potential on the corresponding apertured plate ; a potential is produced thereby to assist the tuned circuit. Specifications 368,721, 450,138, and 451,724 are referred to.