GB528725A - Improvements in or relating to gas- or vapour-filled electric discharge devices - Google Patents

Abstract

528,725. Converting. PATENTVERWERTUNGS.-GES. HERMES. May 13, 1939, No. 14383. Convention date, May 14, 1938. [Class 38 (ii)] [Also in Group XL] In a gas or vapour filled electric discharge devices having liquid, e.g., mercury cathodes in which the instant of ignition is controlled by a control electrode within wide limits, an inductive impedance is connected in series with the cathode and the resultant voltage drop across this impedance is transmitted directly or indirectly to an auxiliary electrode in the neighbourhood of the cathode for preventing quenching of the discharge immediately following the ignition thereof. The discharge device shown in Fig. 1 comprises the vessel 1 with mercury cathode 2, anode 3, control electrode 7 and a series of electrodes 4 connected to a capacitator potential divider 5 for producing a desired potential distribution between the anode and cathode. The current supply source is shown at 12, load at 13, and resistances 6 for damping oscillations. The excitation anode 8 is connected through a resistance 9, battery 10 and inductance 11 in the cathode. In modifications the voltage surge occurring on initiation of the discharge .may be transmitted to a second auxiliary electrode in the neighbourhood of the cathode and connected in series with a resistance which may be adjusted relatively to the resistance 9, and the circuit of this second auxiliary electrode may be inductively coupled to the inductance 11 while the anode 8 is connected directly to the cathode. Fig. 4 shows an arrangement in which the auxiliary electrode is used to take over a part of the discharge surge on the initiation of the discharge, and consists of a mercury pool 17 connected through a resistance 18 to the end of the inductance 11. The resistance 18 is adjusted so that the discharge flowing to the exciter anode 8 is from the cathode. A suitably dimensioned resistance 21 may be connected in parallel with the inductance 11 to damp oscillations therein. To facilitate the change over of the discharge to the electrode 17, an ignition spot may be produced by an ignition pin dipping therein and functioning in dependence on the drop in voltage across the cathode inductance.