GB534474A - Improvements in or relating to electron multipliers - Google Patents

Abstract

534,474. Electron multipliers. BOSCH, F. J. G. VAN DEN., and VACUUM-SCIENCE PRODUCTS, Ltd. Aug. 23, 1939, Nos. 24307 and 24819. [Class 39 (i)] The control electrode 20 for the primary electrons of an electron multiplier is used in combination with two accelerating electrodes 21, 22 on opposite sides and operating at potentials which are positive with respect to the cathode 11 and may be the same as the first of a series of secondary electron emitting cathodes 16. A second control electrode 23 may be disposed between the cathode 11 and the electrode 21. The control and accelerating electrodes may consist of discs with central apertures in line with the emissive surface of the cathode, and the electrode 22 may have a tubular expansion 24 and additional disc member 25 integral therewith. Alternatively these electrodes may be formed of perforated or mesh material, in which case the electrodes 21, 22 are joined by a wall of continuous or grid construction. The multiplier may comprise a number of secondary cathodes as described in Specifications 516,621 and 531,541. The cathode construction is as described in Specification 531,821 and consists of a tube 10 with a disc like part 11 provided with an emissive coating. A second emissive coating is provided on the tube and coacts with a grid 12 and anode 13 to form a triode enclosed in a screening member 14, 15, by which local oscillations are produced and applied to one of the control electrodes, while incoming signals are applied to the other.