This paper presents a simple but complete 2D model for helical flux-compression generators that overcomes many of the limitations present in existing zero-dimensional models. The generator circuit is effectively decomposed into separate z and; current carrying circuits, with each of the; circuits (rings) corresponding to a different current. Use is also made of a technique by which these rings are sequentially switched out of circuit. The approach proposed opens the way to a full understanding of the behavior of cascade systems of generators inductively coupled by dynamic transformers using the so-called flux-trapping technique. In addition, the model can also yield an important insight into the phenomena that differentiates the performance of small generators when primed by a capacitor, a battery, or an externally produced magnetic field. Finally, the numerical code developed in the paper can readily be adapted to model high-energy and high-current generators in which the helical coil and the armature are of variable geometry. Valuable design information is provided on the magnetic and the electric field distributions within the generator and on the likely radial and axial movements of the stator turns.

This paper describes exploding foil opening and closing switch techniques for use in capacitor bank and flux compressor output conditioning circuits. A simple approach was evolved during an extensive experimental programme, aimed at producing a current pulse with a rise time of a few nanoseconds from the output of a flux compressor (or flux compression generator). Capacitor-based experiments provide data for an empirical model for copper foils, used subsequently in a computer program to predict the results of experiments in which exploding foils are used as both opening and closing switches. The switches operate automatically, thus avoiding the problems of triggering between stages of a conditioning circuit. Data from a 1 MJ flux-compressor exploding-foil opening-switch experiment with a run time of 160 mu s are presented and analysed using the theoretical model.

The paper details capacitor bank experiments performed to assess the performance of a plasma erosion opening switch (PEOS). A description is given of the PEOS, which was of an inexpensive and expendable design, and was intended for use as the final stage of a flux compressor output conditioning circuit. Techniques usicg automatically operating exploding foils, as both opening and closing switches, condition the 9ps quarter-wave output pulse from the capacitor bank to a 400ns pulse to the PEOS. An outline is given of the computer modelling and the experimental procedures used to establish the optimum operating conditions, and results are presented which illustrate the behaviour of the PEOS.

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This paper describes the development of a very efficient computer model for the design and performance prediction of explosive-driven helical generators. The model is based on simple theoretical considerations. Validation of the model is achieved by comparing the theoretical and measured performances of existing both high- and low-energy generators. It is shown that, although the basic model predicts accurately the load current history of high-energy generators, a somewhat more elaborate model is needed for low-energy devices. The model has been used in the design of a simple 1 MJ generator with an eight-section stator coil, intended for use as a current source in an investigation of high-current conditioning systems. A description is given of the construction and testing of this device. Experimental results are in accordance with predictions from the design code and establish that, when primed with 40 kJ at 50 kA from a capacitor bank and using 15 kg of high explosive, the generator is capable of delivering an output of 1 MJ at 7 MA to a coaxial load.