Momentum equation for arc-driven rail guns

Journal Article · Sat Dec 01 00:00:00 EST 1984 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.333880· OSTI ID:6338050

Batteh, J H

In several models of arc-driven rail guns, the rails are assumed to be infinitely high to simplify the calculation of the electromagnetic fields which appear in the momentum equation for the arc. This assumption leads to overestimates of the arc pressures and accelerations by approximately a factor of 2 for typical rail-gun geometries. In this paper, we develop a simple method for modifying the momentum equation to account for the effect of finite-height rails on the performance of the rail gun and the properties of the arc. The modification is based on an integration of the Lorentz force across the arc cross section at each axial location in the arc. Application of this technique suggests that, for typical rail-gun geometries and moderately long arcs, the momentum equation appropriate for infinite-height rails can be retained provided that the magnetic pressure term in the equation is scaled by a factor which depends on the effective inductance of the gun. The analysis also indicates that the magnetic pressure gradient actually changes sign near the arc/projectile boundary because of the magnetic fields associated with the arc current.

• Research Organization: Science Applications, Incorporated, Marietta, Georgia 30062
• OSTI ID: 6338050
• Journal Information: J. Appl. Phys.; (United States), Vol. 56:11
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
RAILGUN ACCELERATORS
EQUATIONS OF MOTION
LINEAR MOMENTUM
ELECTRIC ARCS
IMPACT FUSION DRIVERS
MAGNETIC FIELDS
MATHEMATICAL MODELS
MOMENTUM TRANSFER
ACCELERATORS
CURRENTS
DIFFERENTIAL EQUATIONS
ELECTRIC CURRENTS
ELECTRIC DISCHARGES
EQUATIONS
PARTIAL DIFFERENTIAL EQUATIONS
700208* - Fusion Power Plant Technology- Inertial Confinement Technology