GB486888A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

486,888. Electron multipliers. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., and BANKS, G. B. Dec. 11, 1936, No. 34136. [Class 39 (i)] In electron multipliers of the type utilizing secondary emission, the cathodes 2a ... 2k, Fig. 1, are in the form of strips disposed axially on the surface of a cylinder and insulated from each other, and the field electrodes 3a ... 3k are similarly disposed insulated strips arranged on the surface of a coaxial cylinder and each opposite and preferably subtending the same angle at the axis of the cylinder as a cathode strip. The electrodes are mounted on mica plates by means of rods, and the whole discharge field is enclosed by the outer envelope 1 and an inner mica cylinder 6. The cathodes are of silver oxidized and treated with caesium after the envelope has been evacuated, an opening preferably being provided at the ends of the field electrodes to enable this process to be observed. The first field electrode 3a is of gridlike form or otherwise provided with apertures to permit the passage of light. The output electrode 4 is radially disposed and a mica shield 7, radially disposed, separates it from the primary cathode 2a. An axial magnetic field is produced by an annular coil at the top and bottom of the envelope. Preferably the mica support for the electrodes is notched, as shown at Z, Fig. 5, between the pairs of electrodes to provide a long leakage path between the stages. The interconnections between the electrodes are preferably provided all at one end of the system and external connections taken to a potentiometer &c. through a seal at the other end of the envelope. If desired grids may be provided at suitable places in the electron paths, such as between the output electrode and the last multiplier section.