GB525758A - Improvements in electron multiplier arrangements - Google Patents

Abstract

525,758. Electron multipliers and circuits therefor. KOLSTER-BRANDES, Ltd., BEATTY, W. A., and CHATTERJEA, P. K. Feb. 28, 1939, No. 6553. [Classes 39 (i) and 40 (v)] An electron-multiplier with one or more secondary-emitting electrodes has at least two non-emitting collecting electrodes one of which is used only for feeding back alternating current to an earlier part of the apparatus. The feedback may be positive or negative depending upon the frequency and the time-characteristic of the multiplier. The collecting electrodes may be made non-emitting by special treatment of the surface, e.g. carbonizing, or by arrangement in such a position that any secondary electrons emitted do not contribute to the multiplying action. As shown, a collecting electrode A<SP>1</SP> is arranged to collect some of the electrons from the secondary-emitting electrode SE<SP>2</SP> and is connected through an impedance ZA<SP>1</SP> to the biassing potentiometer R<SP>1</SP>, the voltage across the impedance being fed back over a variable impedance FB to the circuit of the control grid 12 (either to a cathode resistance R<SP>2</SP> or a grid impedance ZG). In modifications, the feed-back may be taken across part only of impedance ZA<SP>1</SP>, impedance FB may be omitted and ZA<SP>1</SP> made variable. ZA<SP>1</SP> may be connected in series in the grid-cathode circuit, or the feed-back may be to an earlier secondary-emitting electrode. Specification 495,839 is referred to.