The Motion of Bomb Debris Following the Starfish Test

Abstract

Theoretical computations are presented which identify some of the more important processes affecting the debris expansion following the Starfish explosion. A MHD shock wave is formed, through which the moving debris and air plasma is coupled to stationary plasma. The major component of the stationary plasma is produced by the explosion through ionization of neutral air by X rays and by collisions. The detailed behavior of a model MHD shock system with collisional effects is studied by means of a Lagrangian Computer program, and the computed results are compared with photographic data. The data and computations are in good qualitative agreement as to the behavior of the downward and east-west expansion. The upward expansion is slowed partly by the processes mentioned, but it is ultimately stopped and reversed through the action of conduction currents flowing in the F1 layer in a region connected to the moving plasma by way of the field lines.The observed motion of the plasma along the field lines is not correctly predicted by the machine code in its present form. The major source of electron injection at high altitudes was through a jet of plasma directed initially along the field lines toward the south. This jet was concentrated to an extent sufficient to permit it to move in a straight line across the bending B field without deflection, though leaving a trail of ionized material which was guided by the field to the southern conjugate and other points further south. The trail of the jet is quite clearly seen in the photographs. Its observed motion upward and to the west is interpreted in accordance with well known principles governing the motion of a dilute plasma in a nonuniform field.KeywordsField LineConduction CurrentMagnetic MeridianCharge Exchange Cross SectionAlfven SpeedThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.