GB1100109A - Spark-gap switching devices - Google Patents

Abstract

1,100,109. Spark gaps. BROWN, BOVERI & CIE A.G. 22 Dec., 1965 [24 Dec., 1964], No. 54389/65. Headings HID and HlX. A spark-gap switching device includes two main electrodes, each of which forms a spark gap with an intermediate electrode to which a supplementary potential less than the breakdown voltage is applied, and two ignition electrodes for co-operation each with a respective one of the main electrodes, the application of an ignition pulse to the ignition electrodes being effective to trigger simultaneous discharges between the intermediate electrode and both main electrodes. The supplementary potential from a generator 15 is applied via the sheaths of cables 11 and 12 to the intermediate electrode 8, through which pass insulated ignition electrodes 9 and 10 fed with pulses from generator 16. The device may be employed to produce a current surge, e.g. for plasma experiments, in an oscillatory circuit (Fig. 1, not shown) in which a capacitor is discharged through a load, by short-circuiting the load at a current maximum (i.e. a voltage zero) of the discharge. If short-circuiting at the first current maximum only is required, only one of the balancing capacitors 13, 14 connecting the bus-bars 4, 5 is required. The length of the spark gap between the ignition and the intermediate electrodes is preferably half that between the ignition and main electrodes, and the device may be housed in a vessel at either reduced or excess pressure, to permit reduction in the electrode spacings. A mechanical switchslower, but of lower resistance-may advantageously be connected in parallel with the device, and switched subsequent to the latter. Wear around the ignition electrodes is reduced by mutual repulsion of the arcs.