Optimization of an FCG-Based High-Power Microwave System Using Nonexplosive Pulsed Power

This paper presents a nonexplosive pulsed-power system that replicates the output current waveform of a flux compression generator (FCG). The primary purpose of this system is to efficiently test the power conditioning components of an explosively driven HPM system, while drastically reducing the time between tests which are inherent with explosive experiments. The power conditioning system (PCS) of the HPM system includes an energy-storage inductor, an electroexplosive opening switch (fuse), and a peaking gap and serves to match the FCG output characteristics with the HPM diode load requirements. A secondary purpose of the nonexplosive test bed is to provide data points which could be directly compared with those from explosively driven experiments. For this reason, a reflex-triode virtual cathode oscillator (vircator) was connected to the output of the nonexplosive system, and the results of which were compared with similar testing done with an FCG and a compact Marx generator. Since the behavior of the fuse is known to play a critical role in the performance of the PCS, a study was performed on the effect of different fuse designs on the overall performance of the PCS. Specifically, the quality of the electrical connection between the fuse wire array and the rest of the system was tested. Fuse design experiments were conducted with the nonexplosive test bed firing into a water resistor dummy load, which showed a 13% increase in peak load voltage and more than an 11% increase in energy transfer for fuses with improved wire-electrode connection strength. Some basic rules about fuse design, as well as conclusions on the performance of the PCS when driving an HPM load, are given.

I. Introduction

Flux compression generators (FCGs) are devices which use the kinetic energy imparted on a conductor by high explosives to amplify electrical energy. Since an FCG usually operates most efficiently into a small inductive load, its output must be conditioned in order for the FCG to drive higher impedance more resistive loads, such as a high-power microwave (HPM) source. An electroexplosive opening switch (fuse) and an energy-storage inductor, following the output of the FCG, can be arranged to produce the large voltage pulses needed to drive an HPM diode [1]. Since the fuse and the FCG are both single-shot devices, a nonexplosive system has been previously created to reduce the time and financial costs associated with explosive experiments [2]. This system is designed to replicate the unique quasi-exponential rise of an FCG output current and to optimize the power conditioning system (PCS) components of the explosive system. The PCS of the FCG-based HPM source consists of an electroexplosive opening switch (fuse) in series with an energy-storage inductor and a peaking gap to provide load switching.