A Compact, Self-Contained High Power Microwave Source Based on a Reflex-Triode Vircator and Explosively Driven Pulsed Power

Single-shot high power microwave (HPM) systems are of particular interest in the defense industry for applications such as electronic warfare. Virtual cathode oscillators (vircators) are manufactured from relatively simple and inexpensive components, which make them ideal candidates in single-shot systems. The flux compression generator (FCG) is an attractive driver for these systems due to its potential for high energy amplification and inherent single-shot nature. A self-contained (battery operated prime power), compact (0.038 m³), FCG-based power delivery system has been developed that is capable of delivering gigawatts of power to a vircator. Experiments were conducted with the delivery system connected to a resistive dummy load and then to a reflex-triode vircator. In order to optimize the performance of the vircator when driven by the power delivery system, a second experimental setup was constructed using a Marx-generator based system operating at similar voltages and rise-times. Performance measures of the delivery system when discharged into a resistive load will be presented, as well as vircator output power levels and waveforms from both experimental setups.

I. Introduction

The use of High Power Microwaves (HPM) for an increasing amount of unique applications has led to the need for innovative power delivery systems which provide the energy for HPM generation. Traditional pulsed power sources may be unsuitable when volume, weight, cost, disposability and repetition rate are key factors governing a specific design. For applications which require a compact, single-shot, expendable HPM system, the use of explosively driven power sources, more specifically the Helical Flux Compression Generator (HFCG), becomes appealing. HFCGs are transducers which transform the energy stored in the chemicals of High Explosives (HE) to electrical energy by using the kinetic energy of material that is accelerated by the detonated HE to perform work on a magnetic field. Characterized by a low operating impedance (high current, low voltage), an HFCG is not immediately compatible with a higher impedance HPM device. However, an Inductive Energy Store (IES) in series with an Electro-Explosive Opening Switch (EEOS) can be used to condition the output of an HFCG to better match that of an HPM source. The quick interruption of the high current by the EEOS induces a large voltage across the IES, which allows the energy provided by the HFCG to be more effectively transferred to the HPM load. Polevin [1] used two flux compression generators to drive a backwards wave oscillator, with the conditioned output of one flux compressor responsible for establishing the electron beam and the second FCG used to provide a guiding magnetic field. Results from experiments shown in [1] indicate that the system was capable of radiating 1 GW of peak power. Experiments conducted by Xingen [2] produced 38 MW of peak radiated power with a 370 kV pulse from the conditioned output of a single FCG.