Effects of a Finite Debris Density Profile on the Development of the Longmire Shell,
Abstract
Two models of the early-time spherical expansion of a debris plasma into a stationary magnetized plasma are compared. One is essentially that of Longmire, generalized to spherical geometry, while the second differs in possessing a finite (Gaussian) density profile at the leading edge, rather than the discontinuous profiles assumed by Longmire. In the finite-profile case a relatively thick shell of magnetic compression develops where the streaming and ambient plasma densities are comparable. At very early times, the peak magnetic intensity is much lower than that predicted by Longmire. Numerical calculations of high-altitude bursts provide quantitative agreement with analytical results. They also reveal that discontinuous profiles introduce unphysical processes. This confirms the theoretical analysis which shows that the discontinuous model can give rise to superluminous (v>c) electron velocities. It is thus shown that, even in the absence of anomalous plasma dissipative mechanisms, a realistic model of the debris fron is essential in simulating the evolution of the fireball and weapon debris.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1975
- Accession Number
- ADA015617
Entities
People
- D. L. Book
- R. W. Clark
Organizations
- United States Naval Research Laboratory