Synchronized spark gaps combined to multi-primary windings resonant transformer for wideband applications

Abstract

The generation of high-power electromagnetic waves is one of the major applications in the field of High Pulsed Power (HPP). In each case, the HPP generator is made up of a primary energy source and a load, separated by a power-amplification system that forwards the energy from this source to the load. In such a system, the main component is classically a Marx generator or a Tesla transformer for power-amplification. Our structure uses an innovating extremely compact resonant transformer. When the load is an antenna, it is possible to generate electromagnetic pulses. This paper presents the feasibility of a broadband device for electromagnetic radiations based on this new concept. Our ≪ all electric ≫ device is composed of a battery and a DC/DC 300V-10kV converter to load primary capacitors, four triggered spark gap switches, a four-primary resonant transformer generating pulses with a few hundreds kilovolts amplitude, an oil peaking switch in order to sharpen the rise-time of the transformer output signal and a dipole antenna. Our device must transmit waveforms with a wide frequency band. This paper presents particularly the spark gap switches synchronization, the trigger generator realization and the resonant transformer design. Various technological solutions have been tested in order to trigger with delays and jitters as short as possible (about the ten nanoseconds), the best one is presented. The influence of the amplitude and the rise time of the trigger pulse is studied. To generate the pulse trigger, a very compact Marx generator is designed and achieved. The resonant transformer is made of four primary windings, two secondary windings in parallel and a magnetic core. This specific geometry makes it possible to optimize the coupling ratio. First results concerning their combination are also presented.