A Study of Explosively Formed Fuse (EFF) Opening Switch Resistance
A Study of Explosively Formed Fuse (EFF) Opening Switch Resistance

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Published: 2010

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Many pulsed power experiments need pulse shaping to optimize the power flow from a flux compression generator (FCG) to an experimental load. In a laboratory environment this can be a simple task where the switches are not destroyed. However, in experiments with high explosives, where a large amount of damage occurs, a single use EFF opening switch may be a good choice. In an EFF, explosives are used to thin a current carrying sheet of aluminum as it is forced into a grooved dye. The current is modified by the time dependent changes in resistance as the aluminum is stretched. We will correlate the hydrodynamic effects with resistance. The hydrodynamic profile is determined by Mesa-2D, a well proven hydrodynamics computer code, and MA THEMA TICA is used convert material contours into total resistance using the resistivity as a function of time from various sources. Experimentally, we will determine the actual resistance and compare it with the calculated values. We have used these switches for decades but still do not understand the details of the physics. The resistance change may be due to several processes but in this paper we will concentrate on stretching as the most important contribution. Also, in this paper we will compare the details of the hydrodynamics with the details of experimental and calculated resistance and hopefully generate a predictive model for future designs with other geometries and materials.

Explosively Formed Fuse Opening Switches for Multi-joule Applications
Explosively Formed Fuse Opening Switches for Multi-joule Applications

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Published: 2006

Total Pages:

ISBN-13:

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High explosive pulsed power (HEPP) systems are capable of generating very high energies in magnetic fields. Such stored energy is usually developed on time scales of a few tens or hundreds of microseconds. Many applications require shorter pulses and opening switches provide one way to use the large energy available for faster applications. With current flowing in an inductive circuit, introducing resistance produces voltage that can be used to drive current into a load. For an opening switch with a fast rising resistance, the load current rise time is determined by the R/L time constant of the circuit. A significant fraction of the circuit energy must be dissipated in the process, and in applications where very large energies must be dealt with only a few types of switches can be used. Experiments with high explosive driven opening switches have produced a few switches that can carry tens of MA current, and open on the time scale of one or a few [mu]s. [sup 1] We have specialized in a type of switch that we call an explosively formed fuse (EFF) switch at levels of [approximately]3 TW for 2[mu]s has become routine, and we will describe its characteristics and give data from a number of tests.

Megagauss Magnetic Field Generation, Its Application to Science and Ultra-high Pulsed-power Technology
Megagauss Magnetic Field Generation, Its Application to Science and Ultra-high Pulsed-power Technology

Author: Hans J. Schneider-Muntau

Publisher: World Scientific

Published: 2004

Total Pages: 749

ISBN-13: 9812702512

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The generation of megagauss fields for science and technology is an exciting area at the extremes of parameter space, involving the application and controlled handling of extremely high power and energy densities in small volumes and on short time scales. New physical phenomena, technological challenges, and the selection and development of materials, together create a unique potential and synergy resulting in fascinating discoveries and achievements. This book is a collection of the contributions of an international conference, which assembled the leading scientists and engineers worldwide working on the generation and use of the strongest magnetic fields possible. Other research activities include generators that employ explosives to create ultra-high pulsed power for different applications, such as megavolt or radiation sources. Additional topics are the generation of plasmas and magnetized plasmas for fusion, imploding liners, rail guns, etc.

Procyon Experiments Utilizing Explosively-formed Fuse Opening Switches
Procyon Experiments Utilizing Explosively-formed Fuse Opening Switches

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Published: 1991

Total Pages: 5

ISBN-13:

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In this paper we describe results from tests of an explosive pulsed power system designed to deliver 15--16 MA to a plasma flow switch (PFS). The PFS, in turn, has the goal of switching current to a z- pinch load to produce a 1-MJ implosion for x-ray generation experiments. The system consists of a MK-IX magnetic flux-compression generator, a coaxial inductive store, an explosively formed fuse (EFF) opening switch, and a vacuum power flow/PFS assembly. Figure 1 shows a completed assembly ready to test. Computational modeling of this system is described in another paper in this conference, and important design considerations have been previously published. Vacuum diagnostics are also discussed in a separate paper in this conference as are results from a test in which a conventional foil-fuse opening switch replaced the EFF. We have performed two development tests of the Procyon system. A preliminary reduced energy test (Shot 1) delivered (approximately)13.6 MA to a 25-nH PFS load, and imposed a large voltage spike on the EFF at nominal pinch time without failure. In a full-energy test (Shot 2), the system delivered 20 MA to the EFF without suffering unexpected losses, and demonstrated the proper onset of EFF opening. In the 20-MA test, mistiming between the EFF and the load isolation switches led to transmission line failure that disguised late time opening switch performance and diverted most of the current pulse away from the PFS load. These two tests have provided important system characterization information. In some cases design expectations are confirmed and in others adjustments to initial expectations are called for. Performance details are presented below. 8 refs., 13 figs.

Explosively Formed Fuse Opening Switches for Use in Flux-compression Generator Circuits
Explosively Formed Fuse Opening Switches for Use in Flux-compression Generator Circuits

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Publisher:

Published: 1989

Total Pages:

ISBN-13:

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Explosive-driven magnetic flux compression generators (explosive generators) provide for the generation of large amounts of energy compactly stored in a magnetic field. Opening switches for use in explosive generator circuits allow the energy to be used for applications requiring higher power than can be developed by the generators themselves. We have developed a type of opening switch that we describe as an explosively formed fuse (EFF). These switches are well suited to explosive generator circuits and provide a considerable enhancement of explosive pulsed-power capability. 10 refs., 14 figs.

Magnetocumulative Generators
Magnetocumulative Generators

Author: Larry L. Altgilbers

Publisher: Springer Science & Business Media

Published: 2000-01-14

Total Pages: 442

ISBN-13: 9780387987866

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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.

Advances in Explosively Formed Fuse Opening Switches
Advances in Explosively Formed Fuse Opening Switches

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Publisher:

Published: 1987

Total Pages:

ISBN-13:

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The development of Explosively Formed Fuses along two separate lines is discussed. One design, which has previously been demonstrated to conduct a 9.5 MA 350 .mu.s risetime pulse and interrupt it in 1.2 .mu.s. This scaled up design should operate at up to 15 MA with 20 nH loads. A second design with enhanced performance characteristics is being examined and will be tested on a small scale. This design includes opening switch inductance as part of the inductive store and, as a result, should have shorter pulse transfer times and should be able to be scaled to handle currents up to approx. 25 MA with 20 nH loads.