The design and electrostatic modelling of a high voltage, low jitter trigatron for repetitive operation

This paper describes the design and testing of a trigatron spark gap capable of extended lifetime repetitive operation. The spark gap described has been operated at voltages of up to 500 kV at a repetition rate of 100 pps. The trigatron uses a source of negative ions to ensure an initiatory electron supply which results in sub-nanosecond jitter. A drawback of using trigatrons in repetitive pulsed power applications is that of trigger pin erosion. To minimise this effect, the region around the trigger electrode has been designed using an electrostatic modelling technique. An important consideration when evaluating trigatron performance is that of lifetime. The problems associated with short trigatron lifetimes are usually related to the erosion of the trigger pin resulting in insufficient field distortion of the main electrode region. An electrostatic model was developed which enabled the level of field distortion as a function of trigger pin dimensions and position to be evaluated. The operating lifetime of the spark gap was then predicted by considering the range of pin positions which would result in a field. Repetitive operation was achieved by the use of a pressurised air insulated Marx generator