TIME-DEPENDENT ELECTROMAGNETIC FIELDS OF AN INFINITE, CONDUCTING CYLINDER EXCITED BY A LONG CURRENT-CARRYING CABLE

Theoretical and numerical computations have been made for the quasi‐static, time‐domain electromagnetic response of an infinite, conducting horizontal cylinder stimulated by long cable‐carrying step and ramp‐function type pulses. The effect of higher‐order induced multipoles on the secondary electric and magnetic field components is analyzed in detail, and the “threshold distances” at which individual multipoles become effective (contributing more than 5 percent of the secondary field) are presented. Also, the field fall‐off directly above the body and the variations in different induced‐field components along a traverse perpendicular to the strike of the ore body are examined.