The Effect of Finite Conductivity on MHD Instabilities in Axisymmetric Shaped Charge Jets
Abstract
In an earlier report by Powell and Littlefield, the effect of azimuth magnetic fields on the stability of an axisymmetric shaped charge jet was investigated, assuming the magnetic Reynolds number was very large. Typical magnetic Reynolds numbers for shaped charge jets, however, are approximately 10, which is not large enough to justify the assumption. The present study relaxes this assumption to determine the effects of finite conductivity on the stability of the jet. An axial electric current is introduced in the jet at time t = 0 and permitted to diffuse over time. Linear perturbation theory is employed to determine the time evolution of small disturbances to the idealized motion of the jet. Solutions to the first-order equations indicate that disturbances in the magnetic field and pressure distributions vary significantly, depending on the magnetic Reynolds number. The growth rate perturbations to the boundary, however, indicates that jets of finite conductivity are only slightly more stable than equivalent jets of infinite conductivity. The behavior of these instabilities is discussed in terms of the applicable physical mechanisms.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1992
- Accession Number
- ADA247622
Entities
People
- David L. Littlefield
Organizations
- Ballistic Research Laboratory