Flux-compression dynamic transformers as pulsed-voltage sources

During recent years, the pulsed power group at Loughborough University has developed various electromagnetically driven flux-compression generators. Using thetas-pinch geometry and injecting an initial magnetic field of 2.5 T, ultrahigh magnetic fields in excess of 300 T have been generated in aluminum liner implosions. The fields have a time rate-of-change of up to 350 MT/s. Z-pinch imploding geometry was also investigated, using a cylindrical electric gun with a 50 micron thick aluminum fuse. Helical dynamic transformers were implemented and tested for both geometries, and recordings are presented of the fast-rising high-voltage pulses that were obtained. Potential techniques are suggested and ways to modulate the voltage pulses are demonstrated

I. Introduction

In a dynamic transformer, either the primary or the secondary winding is accelerated rapidly under the influence of an external explosive or electromagnetic force. As a consequence of the resulting characteristics, these transformers are employed in various techniques for inductively coupling chains of explosively driven helical flux-compression generators (FCGs) termed FLUXAR systems [1]. In these, the single-turn primary winding of the transformer is fed from the first-stage of an FCG system and the dynamic (or flux trapping) secondary is a helical FCG coaxial within the primary coil [1].