Quadrupolar electromagnetic field from detonation of high explosive charges on the ground surface

Abstract

Experimental results of a study of electromagnetic fields due to detonation of high explosive charges with mass of a few kilograms are presented in this paper. Data show that in the initial stage of explosion the fields decrease as the fourth power of distance. Such a quadrupolar type of field contradicts the concept that an explosion is characterized by an effective electric dipole. A theoretical analysis is given based on expansion of an electromagnetic field in multipole moments. The theory is used to make estimates of the quadrupolar and dipole moments of the electric charge system resulting from an explosion occurring at the Earth's surface; calculations of electric fields thus produced are similar to those observed.