GB811452A - Magnetic electron multiplier circuits - Google Patents

Abstract

811,452. Electron multipliers ; electrode materials. BENDIX AVIATION CORPORATION. Dec. 29, 1955 [Jan. 3, 1955], No. 37305/55. Class 39(1). An electron multiplier arrangement, particularly for use with a mass spectrometer, comprises secondarily emissive electrodes 16-28 at different potentials for producing a multiplied flow of electrons under the combined action of the electric field and a magnetic field produced by the pole-pieces 48, and a pair of auxiliary electrodes 32, 34 defining a channel leading from the main flow path of the electrons, the electric field in the channel being controllable to divert electrons nito the channel or prevent their ingress therein. A zero or nearly zero electric field is normally present across the channel and a field is applied in pulses across the channel, to divert electrons into it, from the pulse forming circuit 46 at instants corresponding to the arrival of ions of a predetermined group from the time-of-flight mass spectrometer 10, 12, 14. Electrons diverted into the channel strike a collector electrode 36 connected to an indicator such as a cathode-ray oscilloscope 40. Electrodes 33, 35 at the other end of the channel are at small opposite potentials. The 32, 34 may be planar and arranged perpendicularly to the multiplier electrodes or may be curved and arranged otherwise. The electrodes 16-28 can be formed of a beryllium-copper alloy having approximately 2 per cent. by weight of beryllium.