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Projectile transverse motion and stability in electromagnetic induction launchers [electronic resource].

Published:
Washington, D.C. : United States. Dept. of Energy, 1993.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description:
13 pages : digital, PDF file
Additional Creators:
Sandia National Laboratories, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary:
The transverse motion of a projectile in an electromagnetic induction launcher is considered. The equations of motion for translation and rotation are derived assuming a rigid projectile and a flyway restoring force per unit length that is proportional to the local displacement. Linearized transverse forces and torques due to energized coils are derived for displaced or tilted armature elements based on a first order perturbation method. The resulting equations of motion for a rigid projectile composed of multiple elements in a multi-coil launcher are analyzed as a coupled oscillator system of equations and a simple linear stability condition is derived. The equations of motion are incorporated into the 2-D Slingshot circuit code and numerical solutions for the transverse motion are obtained. For a launcher with a 10 cm bore radius with a 40 cm long solid armature, we find that stability is achieved with a restoring force (per unit length) constant of k ≈ 1 × 10⁸ N/m². For k = 1.5 × 10⁸ N/m² and sample coil misalignment modeled as a sine wave of 1 mm amplitude at wavelengths of one or two meters, the projectile displacement grows to a maximum of 4 mm. This growth is due to resonance between the natural frequency of the projectile transverse motion and the coil displacement wavelength. This resonance does not persist because of the changing axial velocity. Random coil displacement is also found to cause roughly the same projectile displacement. For the maximum displacement a rough estimate of the transverse pressure is 50 bars. Results for a wound armature with uniform current density throughout show very similar displacements.
Report Numbers:
E 1.99:sand--93-1765c
E 1.99: conf-940481--3
conf-940481--3
sand--93-1765c
Subject(s):
Other Subject(s):
Note:
Published through SciTech Connect.
12/31/1993.
"sand--93-1765c"
" conf-940481--3"
"DE94005284"
"GB0103012"
7. symposium on electromagnetic launch technology,San Diego, CA (United States),20-24 Apr 1994.
Shokair, I.R.
Funding Information:
AC04-94AL85000
View MARC record | catkey: 14692598