4 research outputs found
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Arc Initiation for the Electromagnetic Powder Deposition Gun
The instrumentation, interpretation of data, and subsequent decisions regarding the direction of system development are discussed. Important system parameters, their impact on system performance, and techniques to measure them are presented. The electromagnetic powder deposition system is based on railgun technology developed by the Department of Defense. The system drives an ionized plasma sheet down the length of a railgun, reaching a final plasma velocity of 4 km/sec. The high velocity plasma, in turn, snowplows a shock compressed gas column in front of it. This gas column sweeps through a powder cloud and accelerates it by viscous drag to a final velocity of 2 km/sec. Important system parameters include particle velocity, gas velocity, gas column pressure, and plasma propagation and velocity. Diagnostic tools include pressure transducers, a high speed digital framing camera, fiber optics and magnetic probes.Center for Electromechanic
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Multi-Shot Power Supply Using Capacitors for an Electromagnetic Powder Deposition (EPD) Gun
The Department of Defense (DoD) and commercial entities are dependent on chemical plating and coating processes to replace worn or eroded material on damaged parts. Air Force Logistics Centers have been forced to consider replacement methods for repair operations due to the tightening of government regulations on the use of toxic and hazardous materials. The electromagnetic coating process is a viable alternative to existing build-up methods, and is based on proven >railgun> technology. Railguns have been under development for 15 years by the DoD and are high energy capacity electrical systems designed for rapid acceleration of an object. Railguns are effective in accelerating projectiles to very high, armor piercing velocities exceeding 2 km/s. Current thermal spray technology limits coating velocities to the 1 km/s range. In the electromagnetic coating process, equipment similar to a railgun accelerates the coating material. The impressive acceleration capability of electromagnetic systems is expected to produce coatings with superior density and bond strength properties. In addition to potentially improving coating properties, the electromagnetic coating process may serve as a replacement for operations that generate hazardous chemical wastes, such as hard chrome plating. The purpose of the program is to identify, develop, and design a production system for high quality coatings in industrial manufacturing and repair operations.Center for Electromechanic
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Scaling Analysis of the Electromagnetic Powder Deposition Gun
The electromagnetic powder deposition (EPD) system employs high velocity gas flow to accelerate powder material to conditions required for high strength plating. The gas flow, however, is not continuous; rather it consists of bursts generated by an electromagnetic railgun and pulsed power system. Each gas burst is created by a high pressure plasma arc which fills a transverse section of the gun. This current carrying arc is driven by the railgun Lorentz force (magnetic pressure) and acts much like a piston, which via a snowplow process accelerates and compresses an ambient gas column to the flow speed required to accelerate powder particles. Analysis of the total system was carried out to provide scaling relations which give guidance in design of the system. Plating considerations define a desired powder velocity; this combined with the choice of working gas and ambient pressure determines the velocity and duration of each gas burst. Selection of gun geometry completes the definition of the pulsed power system requirements. An outline of the analysis is presented along with the physical models used.Center for Electromechanic