26 research outputs found
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Formation of Amorphous Metal By Hypervelocity Impact
The Center for Electromechanics at The University of Texas at Austin has investigated the use of an electromagnetic railgun accelerator for the deposition of non-crystalline metals. The two main objectives of the study were to produce non-crystalline metal deposits in single thin layers (˷ 25lJm thick) and to determine the feasibility of building thicker layers by making multiple deposits. Deposits have been analyzed using a variety of techniques, including electrical resistivity and resistivity ratio, x-ray diffraction, and transmission electron microscopy. Differential scanning calorimetry was carried out at Battelle Columbus Laboratories. The measurements show that CEM-UT -has produced non-crystalline Fe78B13Si9 deposits. Single and multiple-layer non-crystalline deposits with thicknesses of up to 36 µm have been produced, and the upper thickness limit of the technique has not yet been determined.Center for Electromechanic
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Air-Core Compensated Pulsed Alternators
A compensated pulsed alternator is a generator capable of delivering high power energy pulses with current waveform flexibility. This versatile machine has applications in various fields where power density is at a premium. Recent advances in applying fiber/epoxy composites to rotating electrical machinery [l] have greatly enhanced the power density capabilities of this machine. A characteristic of these new machines is an absence of ferromagnetic material in the magnetic circuit, and they are therefore referred to as >air-core'' compulsators. This paper discusses the topological considerations and the capabilities of the family of machines called the air-core compulsators.Center for Electromechanic
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Rotating Machine Development at The University of Texas
The Center for Electromechanics at The University of Texas at Austin (CEM-UT) is specialized in the development of high power, pulsed rotating machines for a variety of applications including fusion experiments, directed energy devices, and electrothermal and electromagnetic accelerators. For many of these applications, compulsators have emerged as viable power supplies. These machines are low impedance alternators which use flux compression to shape the discharge pulse and increase peak power and, to date, have been constructed from ferromagnetic materials. In the past several years, tremendous gains in energy and power densities have been predicted based on the use of composite materials. Glass, graphite, boron and Kevlar reinforced epoxy systems have the advantage of superior strength and stiffness, and are much lighter when compared to their metal counterparts. Two major efforts in which composite based (air-core) compulsators are being developed are now coming to fruition. Additionally, conceptual designs of several advanced concepts covering a wide range of pulse lengths and applications have been performed. The purpose of this paper is to report on the status of the machines currently being fabricated and describe the next generation of high performance compulsators.Center for Electromechanic
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Design And Testing of a Continuous Duty Current Collectors
The Center for Electromechanics at The University of Texas at Austin (CEM-UT) is involved in brush research to develop sliding electrical contacts capable of high current density (2 kA/cm2), high slip speed (200 m/s), continuous operation. The preferred approach is to actively cool the contact by introducing a coolant into the brush-rotor interface. Preliminary testing of this concept has been performed with encouraging results. Design of a contact will be presented along with test results from a single point brush tester capable of 200 m/s slip speed with externally supplied current Results from the high speed brush tester (HSBT), a homopolar generator capable of 400 m/s operation, will also be presented.Center for Electromechanic
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Flux Compressors for Sub-Millisecond Pulses
The Center for Electromechanics at The University of Texas at Austin (CEM-UT) has been developing specialized pulsed power supplies for a variety of applications. The compensated pulsed alternator (compulsator) was invented [l] at CEMUT in 1978. At that time, it was developed as a power supply to drive laser flashlamps. Since then, due to its tremendous potential, it has been applied to diverse fields such as fusion, directed energy weapons, low frequency sound sources, electromagnetic (EM) launcher, and a variety of industrial applications. Several of these machines have been built and tested, successfully demonstrating the principle of operation. This paper provides an overview of short (< 1 ms) pulsewidth compulsators. A brief background is presented first followed by a discussion of the state of the art air-core compulsators and their capabilities. Some insight into the means of further reducing the pulse width is also provided.Center for Electromechanic
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Fabrication of a Compensated Pulsed Alternator for a Rapid Fire Railgun System
This paper presents a detailed description of fabrication of the compensated pulsed alternator (compulsator) for a rapid-fire railgun system. Presented are fabrication techniques and assembly processes developed specifically for a large pulsed power generator, including stator lamination assembly and armature and field winding fabrication techniques. The horizontal shaft, six pole compulsator design incorporates a rotating field and passive compensation. When completed, the compulsator will generate a 2-kV open-circuit voltage and supply 944-kA, 2.45-ms pulses to the 3-m railgun. Since high energy per unit volume ratios are desirable in pulsed power generators, emphasis is put on reducing weight and volume. Consideration for these areas are evident throughout the machine.Center for Electromechanic
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Current Collectors Operating in High Magnetic Fields
An air core, superconducting field coil, self-motored, pulsed homopolar generator has been built and tested. This device uses multiple voltage generating passes and five Tesla magnetic field density to develop open circuit voltage of 500 V. Early testing of this machine showed that the original designs for the motoring and armature current collection systems failed during operation in high external fields. Because this generator is similar to self excited, air core, improved energy devices in the requirement for current collection in high magnetic fields, new designs for both the motoring and armature brushgear systems were developed. A hinged mechanism is used to support the motoring brush, where the current is conducted by a laminated shunt. This design results in significant improvement in sensitivity to contact wear. The armature brushes are compensated in the region of the sliding contact itself, in order to minimize the effect on contact load. An idle (non-current carrying) trailing arm provides dynamic stability. Both designs have been analyzed for thermal and mechanical stability. Static prototypes have been built to verify overall spring rate and fabrication procedures. Dynamic testing of the motoring brush system is scheduled on a high speed contact test system, at slip speed, current density, and duration similar to rated performance in the high voltage homopolar generatorCenter for Electromechanic
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The Design, Assembly, and Testing of an Active Rotary Flux Compressor
A 20-cm diameter rotor active rotary flux compressor has been fabricated at the Center for Electromechanics, the University of Texas at Austin, (CEM-UT) to verify the predicted advantages of fully laminated ferromagnetic rotor and stator construction. An unsaturated flux compression ratio (Lmax/Lmin) of 46:1 has been achieved. Measured inductance values verify space harmonic magnetic field distribution code predictions. Under short circuit testing pulse widths less than 600 μs and current gains in excess of 15:1 have been obtained at a rotor speed of 63 percent of the first rotor critical speed.Center for Electromechanic
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The Rebuilding and Testing of an Active Rotary Flux Compressor
Center for Electromechanic
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The Conceptual Design of a Lightweight Compulsator-Driven Electromagnetic Accelerator
The development of light-weight pulsed power supplies which can deliver significant amounts of energy in a properly conditioned pulse has been an issue throughout the investigation of electromagnetic (EM) launchers and other areas of high-power physics research. Compensated pulsed alternators (compulsators) are low impedance alternators which are capable of producing currents in the MA range. In recent years it has become apparent that the compulsator is well suited for driving EM guns. The generators have the high energy density inherent in rotating machines, can supply repetitive pulses, and eliminate the need for the high-current opening switch required in homopolar generator driven systems. Ultimately, compulsator-driven EM gun systems may replace conventional chemical weapons. This paper describes the first attempt to design and fabricate a self-contained, compulsator-driven, portable EM gun system.Center for Electromechanic