Generation of Artificial Geomagnetic Micropulsations with a Large Ground-Based Current Loop
Technical rept. Jan 1971-30 Jun 1972
STANFORD UNIV CA STANFORD ELECTRONICS LABS
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The purpose of this study is to investigate and, if possible, establish the feasibility of producing artificial geomagnetic micropulsations by using a large horizontal current loop on the ground. Most natural micropulsations appear to be produced by hydromagnetic hm waves propagating in the ionosphere andor the magnetosphere, and the term artificial micropulsations is used to mean artificially produced hm waves with propagation characteristics similar to those of the natural signals. The critical quantity in the generation process for the hm waves is to the amplitude of the magnetic field variation that can be produced in the ionospheric E-region by the ground- based loop. Currents are induced in the conducting earth beneath the loop whenever its current is varied, and these currents have a magnetic field opposing the magnetic field of the loop. If either the conductivity of the earth or the variation frequency is too high the field at E-region heights may be reduced to a level where negligible hm wave amplitudes are produced. The effect of these earth currents is calculated for an assumed single-layer earth and for a wide range of frequencies and earth conductivities.
- Atmospheric Physics