A survey of armature transition mechanisms

Barber, J.P.; Bauer, D.P.; Jamison, K. A.; Parker, J.V.; Stefani, F.; Zielinski, A.E.

doi:10.1109/tmag.2002.805913

Cited by 133 publications

(29 citation statements)

References 14 publications

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“…In both cases some material is removed from the rear part and deposited on the rail surface behind the projectile. Thus, a gap at the rail-armature interface appears, which grows from rear to front [7] - [10]. Besides a structural difference in the growing process, the result is the same: the transition occurs when the gap separates the armature from the rail surface.…”

Section: Introductionmentioning

confidence: 99%

Velocity-induced current profiles inside the rails of an electric launcher

Liebfried

Schneider

Stankevič

et al. 2012

2012 16th International Symposium on Electromagnetic Launch Technology

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Previous investigations showed that an array of novel CMR-B-scalar sensors based on the Colossal Magnetoresistance effect can be used to measure the magnetic field distribution in the vicinity of the rails of a railgun. However, the data obtained suffered from electromagnetic interference. Therefore, the measurement system was considerably improved with respect to the signal quality. In this publication the results obtained during the dynamic operation of the ISL railgun RAFIRA are presented. The magnetic field distribution in the vicinity of the rails was measured at different armature velocities. Additional information was obtained using high-speed camera snapshots. The experimental results are compared with simulations performed with the finite element code COMSOL Multiphysics. In particular, the influence of the armature current on the measurements is discussed. It is concluded that the magnetic field distribution in the vicinity of the rails clearly indicates an increased current concentration in the rear part of the armature-rail contact interface. Moreover, the current concentration depends on the speed of the armature. Velocitydependent skin depths at the surface of aluminum (Dural) rails for projectile velocities ranging between 750 m/s and 1500 m/s are given.

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Section: Introductionmentioning

confidence: 99%

Velocity-induced current profiles inside the rails of an electric launcher

Liebfried

Schneider

Stankevič

et al. 2012

2012 16th International Symposium on Electromagnetic Launch Technology

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“…Nevertheless, transition must be overcome to achieve bore lifetime goals. Research on understanding the phenomena involved are under investigation at present [4], [5]. • Multicyclic phenomena-these involve mechanisms that limit the life of cyclically stressed electromechanical systems.…”

Section: Railgunmentioning

confidence: 99%

Development of a naval railgun

et al. 2005

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The U.S. Navy is considering the development of electromagnetic railguns for future ships for naval surface-fire support (NSFS) and other missions. To reach long ranges, muzzle velocities in excess of 2000 m/s with projectile flight mass of 16 kg and above are needed. Relatively high firing rates are desired; typically 6-12 rounds per minute, so substantial power demands will be made on the ship. For an electrically driven ship, as in the DD(X) concepts presently being explored by the Navy, an existing electrical infrastructure would be in place that could be modified to recharge the pulsed power supplies for the railgun. This study focused on the railgun, the pulsed power system needed to drive the gun, the power system needed to restore the energy required to match the firing rate, and special ship interfaces. Railgun concepts and sizing for the NSFS mission were undertaken, and research and development issues of importance for the success of a future system were identified. Recommendations for analytical and experimental studies that should be undertaken to further address these issues are provided.Index Terms-Electromagnetic railgun, fire support, kinetic energy, projectile, pulsed power.

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“…It may lead the local material of armature to melting, losing contact, and discharge transition [4], [5]. Transition not only wastes energy, affecting the system efficiency, but also causes unevenness of interface, resulting in gouging and a short lifetime of rail(s).…”

Section: Introductionmentioning

confidence: 99%

Physical Principle and Relevant Restraining Methods About Velocity Skin Effect

Xiang

Lei

et al. 2015

IEEE Trans. Plasma Sci.

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Velocity skin effect (VSE) is a kind of current clustering phenomenon, which occurs at the sliding contact interfaces between the high-speed armature and the stationary rails of electromagnetic railgun launchers. Serious current clustering is disadvantageous to the launching performance. The typical current clustering phenomena in static conductors are classified, and the physical principle of VSE is analyzed in this paper. The physical principle in rails is just skin effect because of the short rise time of the accepted pulse current, and the physical principles in armature are clustering near small source and clustering along short path of steady current owing to the continuity characteristic or Laplace equation. The corresponding methods to restrain VSE are deduced and classified as follows: 1) lengthening the contact surface; 2) adding a hard and resistive cladding on the rail's sliding surface; 3) narrowing the interface; 4) adopting a U-shaped armature instead of cuboid one; and 5) controlling the armature legs' thickness/width distribution. An equivalent 3-D model for VSE is adopted, and simulation is carried out for a complex form of armature leg. The uniform current in the interfaces is accomplished, with which the typical uniform index is about 66%. VSE is restrained according to the simulation result. The physical principle, the relevant restraining methods, and the equivalent model are significant to railgun research work.

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A survey of armature transition mechanisms

Cited by 133 publications

References 14 publications

Velocity-induced current profiles inside the rails of an electric launcher

Velocity-induced current profiles inside the rails of an electric launcher

Development of a naval railgun

Physical Principle and Relevant Restraining Methods About Velocity Skin Effect

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