A survey is made of applications where explosive-driven magnetic flux compression generators have been or can be used to directly power devices that produce dense plasmas. Representative examples are discussed that are specific to the theta pinch, the plasma gun, the dense plasma focus and the Z pinch. These examples are used to illustrate the high energy and power capabilities of explosive generators. An application employing a rocket-borne, generator-powered plasma gun emphasizes the size and weight potential of flux compression power supplies. Recent results from a local effort to drive a dense plasma focus are provided. Imploding liners ae discussed in the context of both the theta and Z pinches.
While the basic operating principles of Helical Magnetic Flux Compression Generators are easy to understand, the details of their construction and performance limits have been described only in government reports, many of them classified. Conferences in the field of flux compression are also dominated by contributions from government (US and foreign) laboratories. And the government-sponsored research has usually been concerned with very large generators with explosive charges that require elaborate facilities and safety arrangements. This book emphasizes research into small generators (less than 500 grams of high explosives) and explains in detail the physical fundamentals, construction details, and parameter-variation effects related to them.
Characteristics are presented for two different types of explosive driven flux compression generators and a megavolt pulse transformer. Status reports are given for rail gun and plasma focus programs for which the generators serve as power sources.
A discussion of explosive pulsed power systems and their applications, this book consists of 7 chapters. The first five describe the basic physics of these sources and their ancillary equipment, based on a manual for training engineers in Russia. Chapter 6 is a description of codes and methodologies used at Loughborough University in the UK to build flux compressors, while Chapter 7 covers two specific applications: high power lasers and high power microwave sources. The book introduces all types of explosive power sources and their ancillary equipment, the procedures required to build them, and specific applications.
A type of explosive driven generator, called a plate generator, is described. It is capable of delivering electrical energies in the MJ range at TW power levels. Plane wave detonated explosive systems accelerate two large-area metal plates to high opposing velocities. An initial magnetic field is compressed and the flux transferred to an external load. The characteristics of the plate generator are described and compared with those of other types of generators. Methods of load matching are discussed. The results of several high-power experiments are also given.
Compact, high-gain magnetic flux compressors (FCGs) are convenient sources of substantial energy for plasma-physics and electron-beam-physics experiments, but the need for high-voltage, fast-rising pulses is difficult to meet directly with conventional generators. While a variety of novel concepts employing simultaneous, axially- detonated explosive systems are under development, power-conditioning systems based on fuse opening switches and high-voltage transformers constitute another approach that complements the fundamental size, weight, and configuration of the small helical flux compressor. In this paper, we consider first a basic inductive store/opening switch circuit and the implications associated with, specifically, a fuse opening switch and an FCG energy source. We develop a general solution to a transformer/opening switch circuit--which also includes (as a special case) the direct inductive store/opening switch circuit (without transformer) and we report results of one elementary experiment demonstrating the feasibility of the approach. 9 figs.
Large-scale helical flux compression generators deliver energies in the range of 10--50 MJ in economical, flexible packages for powering a variety of plasma and electron beam experiments. While conventional, end-detonating, helical generators are simple and reliable, they have the disadvantage of delivering their energy over long timescales, up to 400--500 .mu.s, and at relatively low output voltages. Many experiments require faster risetimes than can be delivered by a helical FCG directly, and inductive systems utilizing high current interrupting switches can be employed to match generator performance to load requirements. For this experiment, a 15-MJ class helical flux compression generator was selected as the primary energy source. This flux compressor is a modification of a design proposed by Pavlovski in 1979 and used routinely in Los Alamos programs. The generator consists of a multiple conductor, multiple pitch, helical stator and a hollow copper armature containing a 60-kg charge of PBX 9501 high explosive (HE) which is initiated by a small plane wave lens at the end opposite the output. 8 refs., 12 figs.
The high performance explosively powered flux compression generator (FCG) represents a proven source of very large electrical energies, at very high currents, low impedances, and modest powers that is suitable for powering a variety of plasma and beam experiments. Flux compressors have the advantage of delivering energy at low and high current and are ideal for energizing inductive energy storages. They are straightforward, compact, and inexpensive, when evaluated on the basis of cost per joule for a limited number of experiments. Conventional flux compressors have the disadvantage of delivering these enormous energies on relatively long timescales thus making some form of power conditioning essential for powering many interesting loads. Since flux compressors are ideally suited to energizing inductive loads, power conditioning systems based upon inductive store/opening switch techniques are complementary to FCG energy sources. For some experiments, straightforward application of one of a variety of high-current interrupters can provide the needed power conditioning. For more demanding experiments, multi-stage combination of switches may be required. And for loads requiring voltages in excess of a few hundred kilovolts, opening switches coupled with energy storage transformers are suitable. In this paper, we will review switch concepts that have been used in conjunction with flux compressors which deliver energies in the range of 1--20 MJ. These concepts include conventional electrically-exploded fuses, explosively-formed fuses, plasma-dynamic switches, and combinations of these elements. 6 refs., 12 figs.
A class of explosive magnetic flux compression generators is described that has been used successfully to power rail guns. A program to increase current magnitudes and pulse lengths is outlined. Various generator loss terms are defined and plans to overcome some of them are discussed. Included are various modifications of the conventional strip generators that are more resistant to undesirable expansion of generator components from magnetic forces. Finally, an integral rail gun is discussed that has coaxial geometry. Integral rail guns utilize the rails themselves as flux compression generator elements and, under ideal conditions, are theoretically capable of driving projectiles to arbitrarily high velocities. Integral coaxial rail guns should be superior in some regards to their square bore counterparts.
The explosively-pumped magnetic flux compression generator (FCG) is a pulsed-power current amplifier powered by an explosion. This thesis surveys FCGs, demonstrating their general operation; develops a new magnetic-field-strength-based model for FCGs in the form of a generalized cylinder that more accurately captures losses to magnetic diffusion than commonly employed circuit models, but maintains simplicity in the form of a low order DAE; develops a simplified means of calculating the inductance of FCGs, providing a bridge between the field-based and circuit models; presents a design of a full loop FCG system (a topology underserved by existing literature) and an experimental setup to verify the designed loop generator; and proposes a class of non-explosive magnetic flux compression generators. The designs and models herein provide new tools and jumping-off points for further research into FCGs, particularly in the miniaturized systems gaining popularity and in the potential for reusable flux compression power sources.
