Design and testing of solid armatures for large-bore railguns

Price, J.H.; Fulcher, Clay; Ingram, Mike; Perkins, Dallas; Peterson, D.R.; Zowarka, R.C.; Pappas, J.A.

doi:10.1109/20.22583

Cited by 20 publications

(4 citation statements)

References 9 publications

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“…Due to the so-called "velocity skin effect" (VSE), the current is only flowing through a fraction of the available contact interface area, which results in extremely high current densities. This could be first observed through the asymmetric wear of recovered armatures [1], [2] before it was theoretically examined [3] - [5]. VSE can be explained in a simplified manner by a combination of magnetic diffusion and fast armature movement.…”

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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“…The VSE attracts much attention since erosion especially at the trailing edge of solid armatures was observed (Barber et al 1974;Price et al 1989). Today, the VSE is seen as one of the major reasons for the loss of the solid contact at the rail-armature interface (Chen et al 2007).…”

Section: Contact Transitionmentioning

confidence: 99%

The investigation of electromagnetic processes in electromagnetic launchers using colossal magnetoresistance sensors

Liebfried¹

2011

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“…Judging from the previous published efforts, the study of LCAs is rarely mentioned. On the foundation of SCA and MCA, we can design large caliber armature with some similar principles [3]- [4], but there are unique features of the design [5]. With both armature caliber and mass increased, LCA requires higher energy density source to be accelerated to hypervelocity, which becomes a challenge for both high-energy pulsed power supply and the matching of rail and armature [6].…”

Section: Introductionmentioning

confidence: 98%

Study on current concentration of large-caliber C-shaped armature at current ramp-up stage in square railgun

Tang

Chen

et al. 2014

2014 17th International Symposium on Electromagnetic Launch Technology

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Compared with small and medium caliber railguns, large caliber railguns (LCRs) could be applied in more occasions. Armatures for LCRs could be designed according to studies on small and medium caliber railguns, yet there are some unique features of the design. Current concentration is a special phenomenon in LCR systems, where it's more severe due to high energy density and large current. For a large-caliber armature that has the same muzzle speed as small-caliber armatures, which guarantees the identical velocity skin effect, the skin effect and the induced current are studied and have to be considered as the main influence factors.In this paper, the current distribution and concentration between large caliber armature (90 mm × 90 mm) and small caliber armature (20 mm × 20 mm) are studied and compared. The current distribution coefficients of these two armatures are obtained, it's shown that current density in large armature is more concentrated than the small one. The proportions of induced current to the total current for 90 mm × 90 mm and 20 mm × 20 mm armatures are obtained, which indicate that the induced current is the main reason for current concentration in large-caliber armature. At last, measures to improve current distribution in large-caliber armatures are discussed.

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Design and testing of solid armatures for large-bore railguns

Cited by 20 publications

References 9 publications

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

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

The investigation of electromagnetic processes in electromagnetic launchers using colossal magnetoresistance sensors

Study on current concentration of large-caliber C-shaped armature at current ramp-up stage in square railgun

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