Compact 600 kV multi-primary windings resonant transformer to drive an electromagnetic source

Abstract

Modern pulsed power applications of high power microwave technology require compact power-amplifier. In each case, the high pulsed power generator is made up of a primary energy source and a load, separated by the power-amplification system that forwards the energy from this source to the load. Usually a Marx generator or a Tesla transformer is used as the power-amplifier. Our structure uses an innovative and very compact resonant transformer to drive a dipole antenna. Our complete pulsed power source, named MOUNA, is composed of a set of batteries, a dc/dc converter to charge four capacitors, four synchronized spark gap switches, a resonant transformer generating 600 kV/265 ns pulses, an oil peaking switch and a dipole antenna. The device must transmit waveforms with a wide frequency band and a high figure-of-merit. The paper describes the compact 600 kV multi-primary windings resonant transformer developed in common by Université de Pau and Hi Pulse Company. The resonant transformer is made of four primary windings, two secondary windings in parallel and a Metglas® 2605SA1 amorphous iron magnetic core. An innovative biconic specific geometry makes it possible to optimize the leakage inductance. The transformer mechanical characteristics are: 6 kg weight, 3.4 liters volume, 20 cm diameter and 11 cm width. Design details are explained accurately. Each feature is justified. Calculations of leakage inductance and stray capacitance between primary and secondary windings are presented. Core losses and saturation induction are studied. An LTspice-based study of the power-amplifier is proposed. Finally, the results from two experimental studies are presented. Firstly, the resonant power-amplifier loaded by a compact capacitive charge associated to a homemade capacitive voltage probe specially developed is studied. Secondly, an integrated V-dot probe measures the power-amplifier output inside the electromagnetic source. To conclude, the experimental results are compared to the LTspice simulations and discussed.