Pulsed magnetic flux compression power supplies for hypervelocity powder deposition

After reviewing the process of hypervelocity plasma deposition using augmented railgun technology, the paper presents several new concepts of pulsed rotating electric generators designed to power, on an almost continuous basis, the laboratory system designed and built at The University of Texas Center for Electromechanics (UT-CEM), which successfully validated the method and conducted proof-of-principle experiments. The two different rotating, repetitive pulsed power supplies described in the paper are: (1) an actively compensated flux compressor-alternator (actively compensated compulsator) and (2) a dc machine with series excitation, which so far did not have any application as a generator but proves, due to its self-excitation particularities, to be an almost ideal power source for the railgun. It needs to be emphasized that the augmented railgun and the actively and passively compensated compulsators represent almost mature technologies due to the continuous development of electromagnetic launch technology by the U.S. Department of Defense and especially by the U.S. Army – ready to be applied to many advanced civilian applications as it is the case with the hypervelocity powder railgun accelerators for surface conversion.Center for Electromechanic

A study pertaining to inertial energy storage machine designs for space applications

The preliminary design of a counterrotating fast discharge homopolar generator (HPG) and a counterrotating active rotary flux compressor (CARFC) for space application is reported. The HPG is a counterrotating spool-type homopolar with superconducting field coil excitation. It delivers a 20-ms, 145-kJ pulse to a magnetoplasmahydrodynamic thruster. The peak output current is 42.7 kA at 240 V. After 20 ms the current is 29.7 kA at 167 V. The CARFC delivers ten 50-kJ, 250 microsecond pulses at 50-ms interval to six Xenon flash lamps pumping an Nd glass laser. The flux compressor is counterrotating for torque compensation. Current is started in the machine with a 5-kV, 5-kJ pulse-charged capacitor. Both designs were based upon demonstrated technology. The sensitivity of the designs to technology that may be available in five to ten years was determined

Energy stores and switches for rail-launcher systems

An overview of existing switch and power supply technology applicable to space launch, a new candidate pulsed power supply for Earth-to-space rail launcher duty, the inverse railgun flux compressor, and a set of switching experiments to study further the feasibility of Earth-to-space launch are discussed

25 GW Homopolar Generator Experiment

Early in the design iterations for the Balcones 60 MJ power supply different options were considered, from a single machine to modular homopolar generators (HPGs).[1] A multiple machine option was chosen to provide greater system flexibility. Envisioned uses for the power supply were to weld up to 100 in.2 of metal, heat a 100 lb steel billet to forging temperature in 2 to 4 s, and conduct high level electromagnetic gun experiments.[2] A study involving detailed computer optimization compared drum type HPGs to disk type machines. For fixed location (such as large proof of principle laboratory experiments) the higher energy transfer efficiency and lower cost perjoule delivered made the drum configuration more attractive. The compact disk design was better for mobile applications where minimum mass is the primary consideration.[3] The six drum HPGs installed in the underground hexagonal pit in the Balcones lab are shown in figure 1.Center for Electromechanic

Staged opening switch

" A staged switch for conducting a large electrical current for an indefinite time period and then rapidly switching the current into a load circuit. The switch comprises a first stage which can conduct a large electrical current for an indefinite time period without damage to the stage and a second stage which is a fast-opening element. The first stage includes primary and secondary contacts wherein the primary contacts conduct a charging current and the secondary contacts divert the current into the fast-opening second stage. The secondary contacts ""make"" before the primary contacts ""break"", reducing the damage to the contacts which might otherwise be experienced. The second stage is a low-inductance element which reduces the level of energy absorbed by the first-stage contacts, minimizing damage to the contacts. The second-stage element may be constructed in a cartridge and may be loaded into the switch using an autoloader device. "Board of Regents, University of Texas Syste

Hypervelocity Powder Deposition using Pulsed Power Magnetic Flux Compression Devices

This paper outlines two original concepts which, in combination, can bring fundamental advances to both manufacturing and materials technologies and the pulsed power approach to them, and describes a laboratory system already built which has conducted proof-of-principle experiments. The first novel concept uses a hypervelocity accelerator for a new thermal spray process using electromagnetic forces to accelerate powder particles to velocities of 2 km/s or higher, more than twice that of the powder velocities of about 1 km/s used by the existing state-of-the-art thermal spray processes (HVOF, D-gun, plasma spray) which are limited by their reliance on the thermodynamic expansion of gases. The second original concept is a pulsed power supply, a new electrical machine-flux compressor with precisely controllable output capable of matching ideally the powder spraying hypervelocity accelerator at any moment of time. Due to the compensation systems, the compulsators are low internal impedance machines designed for pulsed duty and capable of providing large current pulses, with a rapid rise time (in our case, less than 25 /spl mu/s to 80 MW pulsed power) to a low impedance load-a hypervelocity square bore railgun accelerator (SBA) assuring an almost continuous process. After describing the results of some experiments confirming system modeling and performance, the paper concludes with future directions of this research.Center for Electromechanic

Nine-Phase Armature Windings Design, Test, and Harmonic Analysis

A nine-phase armature winding was developed for a large generator. Alternative methods for interconnecting the pole-phase groups were examined. An alternate-pole connection scheme was adopted and a prototype induction motor was constructed to confirm the winding scheme. Since only a three-phase power source was available for testing, the induction motor was tested by using three, three-phase winding sections, one at a time. Air-gap harmonic fields produced some unusual results. These test results and harmonic analyses to explain them are presented herein. The tests confirmed the nine-phase winding scheme that was adopted. The harmonic analyses revealed that the complete nine-phase winding exhibited a very low harmonic content, a distinct advantage of a nine-phase winding for future applications.Center for Electromechanic

Hypervelocity Electromagnetic Gun Development at CEM-UT

Interest in railguns at the Center for Electromechanics at The University of Texas at Austin (CEM-UT) was the result of a visit to the railgun facility at the Australian National University (ANU) at Canberra in 1979. Soon after that visit the concept of a Distributed Energy Store (DES) railgun was invented and the first injected railgun was tested at CEM-UT. When railguns were introduced into the defense community in 1980, the technology started to grow in the United States. With the announcement of the Strategic Defense Initiative (SDI), electromagnetic launcher research took another quantum step. Today CEM -UT is actively testing state-of-the-art launchers on the pulsed power supplies developed at CEM- UT over the past twelve years. In addition, CEM-UT is preparing for the future with the installation of the Balcones Homopolar Generator Power Supply and by maintaining programs in state-of-the-art rep- rated power supply development and hypervelocity launch. A detailed description of the CEM- UT facility is presented in Appendix A at the end of the text.Center for Electromechanic

Design, Analysis, and Fabrication of Two Lightweight, High L’ Railguns

Design, analysis, and fabrication of two railguns with 90 and 30 mm bores utilizing a laminated containment structure are discussed. Laminations are insulated from each other by layers of sheet adhesive, and a composite overwrap is applied to the laminations for longitudinal stiffness. The 90 mm-bore gun is being fabricated for testing as the 9 MJ range gun. Performance specifications for the 90 mm-bore gun are 3.2 MA peak current, 4.0 km/s maximum velocity, and 12 MJ muzzle energy. The 30 mm-bore gun is a one-third scale version of the 90 mm-bore gun, built to develop construction techniques and verify performance. It is designed to be operated at 1 MA with a maximum muzzle energy of 400 kJCenter for Electromechanic

Pulsed Power Accelerators at CEM-UT

An overview of four accelerator programs utilizing pulsed power is presented. The goals of each project, a description of the power supplies and launchers utilized and test results from each program are provided. The four projects presented illustrate a variety of uses for electromagnetic (EM) launchers and the potential advantages and disadvantages of four different launcher systems. Included in the paper are micrometeorite impact studies of 50 to 500 μm diameter glass beads accelerated up to 11 km/s with plasma armatures and 2.5- kg solid armature packages launched at 2.6 km/s (a record 8.1 MJ of muzzle energy). A compact rep-rateable augmented rail launcher and compulsator system weighing less than 1,100 kg is also described. Finally a skid mounted rep-rateable launcher system capable of providing 9 MJ of muzzle energy is discussed.Center for Electromechanic