Electromagnetic Properties of Impact-Generated Plasma, Vapor and Debris Page: 1 of 14
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VSOD
Nov 171995
ELECTROMAGNETIC PROPERTIES OF IMPACT-GENERA T,
PLASMA, VAPOR AND DEBRIS
DAVID A. CRAWFORD* AND PETER H. SCHULTZ**
*Computational Physics and Mechanics Dept. 9232, Sandia National Laboratories, Albuquerque, NM, 87185, USA;
**Department of Geological Sciences, Brown University, Providence, RI, 02912, USA.
Summary-Plasma, vapor and debris associated with an impact or explosive event have been
demonstrated in the laboratory to produce radiofrequency and optical electromagnetic emissions
that can be diagnostic of the event. Such effects could potentially interfere with
communications or remote sensing equipment if an impact occurred, for example, on a satellite.
More seriously, impact generated plasma could end the life of a satellite by mechanisms that are
not well understood and not normally taken into account in satellite design. For example,
arc/discharge phenomena resulting from highly conductive plasma acting as a current path
across normally shielded circuits may have contributed to the loss of the Olympus experimental
communications satellite on August 11, 1993. The possibility of significant storm activity
during the Leonid meteor showers of November 1998, 1999 and 2000 (impact velocity, 72
km/s) has heightened awareness of potential vulnerabilities from hypervelocity electromagnetic
effects to orbital assets. The concern is justified. The amount of plasma, electrostatic charge
and the magnitude of the resulting currents and electric fields scale nearly as the cube of the
impact velocity (ac v2.6). Even for microscopic Leonid impacts, the amount of plasma
approaches levels that could be dangerous to spacecraft electronics. The degree of charge
separation that occurs during hypervelocity impacts scales linearly with impactor mass. The
resulting magnetic fields increase linearly with impactor radius and could play a significant role
in our understanding of the paleomagnetism of planetary surfaces.
The electromagnetic properties of plasma produced by hypervelocity impact have been
exploited by researchers as a diagnostic tool [1-3], invoked to potentially explain the magnetically
jumbled state of the lunar surface [1-4] and blamed for the loss of the Olympus experimental
communications satellite [5]. The production of plasma in and around an impact event can lead
to several effects: (1) the plasma provides a significant perturbation to the ambient magnetic field
via the electromagnetic pulse; (2) it supports the production of transient radiofrequency
electromagnetic fields; (3) it charges ejected debris which, because of inertial separation, leads to
significant electrostatic and magnetostatic field production; and (4) its high electrical conductivity
provides a convenient path for discharge of the resulting high electrostatic fields. Effects (1) and
(2) have been discussed by the authors elsewhere [1-3]. Effects (3) and (4) will be discussed here.
Typical studies of kinetic energy warheads focus on lethality as a function of impactor
momentum or energy as they couple mechanically to the target. At high enough energies,
however, additional physical processes come into play [6]. Vaporization plays an important role
and a partially ionized plasma can form (Figure 1). Impact-generated plasma, charged debris and
magnetic fields have been characterized by laboratory hypervelocity impact experiments and are
shown to be more abundant when certain easily ionized materials (such as alkali metals) are used
in either projectile or target [1-3,7].
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Crawford, D. A. & Schultz, P. H. Electromagnetic Properties of Impact-Generated Plasma, Vapor and Debris, article, November 2, 1998; Albuquerque, New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc620569/m1/1/: accessed May 4, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.