Examination of yield determination by the Magnetic Bubble Effect.

摘要

This report surveys the preliminary work of P. J. Ebert, a proponent of the ''Magnetic Bubble'' Effect, as well as conclusions reached by L. F. Wouters and others. The idea behind the Magnetic Bubble Effect is that an exploding fireball from a surface or subsurface nuclear explosion releases electrons which circulate around the earth's magnetic field lines and create an expanding magnetic dipole which persists underground for (approx equal)0.01 sec. This dipole radiates a low-frequency electromagnetic field through the earth in a diffusive manner because the earth's conduction current overwhelms the displacement current at VLF and ELF frequencies. By using this concept of diffusive fields it might be possible to estimate the yield of an underground nuclear test from transient low-frequency field measurements on or near the ground in the range 1--5km from ground zero. We closely examine the diffusive-field description of the transient fields by L. W. Miller. Miller's work enables us to derive rather easily the ''Green-function'' fields in space and time of a spatially and temporally impulsive vertical magnetic dipole, m(sub z), and horizontal dipole, m(sub x), in a homogeneous earth of scalar electrical conductivity (sigma), magnetic permeability (mu)(sub 0), and relative dielectric constant, (var epsilon)(sub r), and account for the earth-air interface. The fields of an event would be the convolution of these Green-function fields and the temporally evolving m(sub x)- and m(sub z)-dipoles integrated over space. The spectra of the Green-function fields are readily calculated, and multiplied by the magnetic-dipole spectrum to give the event-field spectra. 9 refs. (ERA citation 16:001266)