Patent GB-772615-A (GB)
Title: Improvements in or relating to gas filled electric discharge tubes having a plurality of discharge gaps
IPC: H01J17/48
Filed: 1954-06-30
Abstract: 772,615. Multi-gap cold-cathode tubes. TELEFONAKTIEBOLAGET L. M. ERICSSON. June 30, 1954 [June 30, 1953], No. 19256/54. Class 39(1). In an electronic glow discharge tube containing a plurality of cathodes of laminar form and one or more associated anodes disposed to form a plurality of discharge gaps which are intended to be discharged in turn, all or some of the cathodes are inclined with respect to the normal to an associated anode in such a way that the distance from an associated anode to one edge of an inclined cathode is greater than the distance from such anode to the opposite edge of the inclined cathode, said one edge being adjacent to another cathode which is next in the order of intended discharge. In one arrangement, Fig. 1, the tube comprises an anode A, a group of main cathodes K1, K2, K3 connected to earth, and a group of auxiliary cathodes K12, K23, K34 connected to a positive potential and supplied with negative pulses. A discharge at, for example, the main cathode K2 will prime the adjacent gaps corresponding to auxiliary cathodes K12 and K23, but the striking voltage for Kzs is decreased to a greater extent than for K12 due partly to the decrease of ionization with distance from the discharge and partly to the fact that the righthand edge of cathode K12 lies at a greater distance from the anode than the left-hand edge of cathode K23 and consequently experiences a lower electric field strength. A contributory cause is the fact that the left-hand edge of cathode K23 lies in front of cathode K2 whereas the right-hand edge of cathode K12 lies behind cathode K2. Thus, if a negative pulse is applied to the auxiliary cathodes, K23 will fire and K2 will be extinguished owing to the voltage drop across the anode resistor Ra. The pulse is made sufficiently long to allow K2 time to de-ionize, so that at the end of the pulse K3 fires and captures the discharge. In this arrangement all the cathodes are arranged diagonally. In an alternative arrangement the main cathodes are parallel to the anode and are either connected in two groups each having its own RC circuits or are connected through individual RC circuits to earth. The pulses are applied to an intermediate group of diagonal cathodes. Alternatively the pulses may be applied to the parallel cathodes which are then connected in a single group and the diagonal cathodes connected in groups or individually through RC circuits to earth. In a circular embodiment, in which the cathodes are all arranged diagonally, ten main cathodes are arranged alternatively in two groups each connected to earth through an RC circuit and negative pulses are applied to a group of intermediate auxiliary cathodes, or alternatively the auxiliary cathodes are omitted and the tube is operated by applying either positive or negative pulses to the anode. In the arrangement shown in Fig. 7 the tube comprises ten auxiliary anodes A1 to A10 arranged between the ten cathodes and the main anode, and the tube is operated by applying positive pulses to the auxiliary anodes. Additional electrodes may be provided in association with one or more cathodes for zero return or for the transfer of pulses to further stages of a counting circuit, and a small quantity of a non-rare gas may be added to the rare gas filling to increase the stepping speed.