Magnetic Insulation of MV Pulse Transformers

An ongoing research project at Loughborough University aims to develop compact magnetically-insulated pulse transformers in the megavolt range. The first phase of the work was to design, build and test a 0.5 MV pulser based on a magnetically self-insulated spiral-strip transformer operated in vacuum, and fed from a capacitor bank. The magnetic field needed to insulate the HV secondary winding is established by the primary current of the transformer. A description is given of the novel technique used to grade the electric fields internal to the secondary winding and so prevent an electrical breakdown. The second phase of the project is to produce a 1 MV pulser based on a Tesla transformer, again operated in vacuum. This time the secondary winding insulation is provided by a magnetic field produced by an auxiliary power source. Detailed results of numerical simulations are given for both transformers, and these are validated by comparison with reliable experimental data.