Armature options for hypervelocity railguns

Thornhill, L.D.; Batteh, Jad H.; Brown, J.L.

doi:10.1109/20.22599

Cited by 13 publications

(1 citation statement)

References 3 publications

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“…The velocity skin effect (VSE) is a principal factor that limits the use of a metallic armature in electromagnetic railguns in the regime with sliding metallic contact (Young & Hughes, 1982;Thornhill et al, 1989). A sharp increase in the current density due to the VSE at the contact boundary leads to fast heating of the armature in this region in excess of its melting temperature.…”

Section: The Ultimate Kinematic Characteristics Of Railguns With a Mementioning

confidence: 99%

Problem of Materials for Electromagnetic Launchers

Shvetsov¹,

Станкевич²

2011

Heat Analysis and Thermodynamic Effects

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Section: The Ultimate Kinematic Characteristics Of Railguns With a Mementioning

confidence: 99%

Problem of Materials for Electromagnetic Launchers

Shvetsov¹,

Станкевич²

2011

Heat Analysis and Thermodynamic Effects

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The inverse problem of superfast contact theory for an accelerated body with orthotropic conduction

Karpova¹,

Titkov²,

Shneerson³

1996

J Appl Mech Tech Phys

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Analysis of the ultimate kinematic characteristics of railgun accelerators of solids

Станкевич¹,

Shvetsov²

1999

J Appl Mech Tech Phys

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A comparative analysis of the dependences of the ultimate (under heating conditions) velocity on the dimensions and thermal properties of the projectile and on the length of the railgun is performed on the basis of a numerical solution of two-dimensional unsteady equationsIntroduction. One factor that hinders attainment of high velocities in the acceleration of conducting solids in railguns is the loss of metal contact between the projectile (armature) and the rails (electrodes) and transition to the electric-arc regime of short circuit. Results of numerical simulation of the electrothermal state of the armature show that the temperature of the armature is nonuniform across its section and is maximum in the regions of contact between the rear side of the armature and the rail surface, where there is concentration of current due to the velocity skin effect (VSE) [1][2][3][4]. The velocity of the projectile at which it begins to melt near the contact boundary between the rails and the armature is commonly called the critical or ultimate velocity, i.e., the velocity at which metal contact is still retained. For traditional materials, the ultimate velocity is usually about 1 km/sec, which currently limits the use of conducting solids in railguns. A considerable number of recent papers deal with the search for methods of increasing the critical (ultimate) velocity, or, in other words, decreasing the current concentration due to the VSE. Multilayer bodies with orthotropic electric conductivity, bimetallic rails whose contact side is coated with a layer of a material with high electric resistance, and other approaches (see, for example, [1,[3][4][5][6][7]) were studied. It should be noted that the potentials of composite materials for increasing the ultimate velocity have not been completely clarified. Sometimes, authors draw opposite conclusions. In particular, the statement of Dreizin [5] that a high-ohmic coating is efficient at increasing the ultimate velocity is in conflict with the conclusion of Long and Weldon [3] that such coatings are not recommended for use in railguns of solids. This can be due to the fact that different physical phenomena are considered in the analysis of the heating rate of the armature, and coating materials with different electrothermal properties are used (Mo and C).In the present work, we perform a comparative analysis of the influence of resistive coatings with different electrothermal properties on the ultimate kinematic characteristics of homogeneous and multilayer armatures in the nonarc regime of acceleration. The nonarc regime occurs when the armature does not melt during acceleration. Two physical processes that affect the variation in the temperature of the armature are taken into account: Joule heating and heat transfer. Ignoring the other phenomena responsible for heating of the armature and decrease in the effectiveness of acceleration, in particular friction, we obtain the upper bound for the ultimate velocity in the nonarc acceleration regime. The difference between the res...

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Armature options for hypervelocity railguns

Cited by 13 publications

References 3 publications

Problem of Materials for Electromagnetic Launchers

Problem of Materials for Electromagnetic Launchers

The inverse problem of superfast contact theory for an accelerated body with orthotropic conduction

Analysis of the ultimate kinematic characteristics of railgun accelerators of solids

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