3D electrostatic modeling of an extended lifetime, 100 pps, 500 kV, low jitter trigatron

Two dimensional electrostatic modeling techniques have previously been used to aid the design of a high voltage, low jitter trigatron spark gap. Areas of high electric field stress could be identified at an early stage of the design process and modified, ensuring optimum performance and lifetime of the spark gap switch. This paper describes the extension of the modelling technique using a three-dimensional analysis boundary element method program to design a switch with a predicted lifetime of 10/sup 6/ shots, a single sided jitter of 1 ns and an operating voltage of 500 kV. The use of three dimensional electrostatic analysis has enabled a complete categorisation of the trigatron to be carried out. This has included the effect of space charge in the switching media and surface charge on the insulators (to simulate repetitive switch operation). Further investigations into the effect of trigger pin diameter, the proximity of this pin to the adjacent earth electrode, the earthed electrode profile, the high voltage electrode profile and the position of the trigger pin were also made. The use of 3D analysis enabled capacitance and inductance estimations to be made which could influence the performance of the switching system. Electrode trajectories were also investigated in order to ensure that the optimum switch design had been chosen. The above procedure has led to the production and testing of an extended lifetime, subnanosecond jitter, 500 kV triggered switch which has been operated successfully at repetition rates of up to 100 pps.