Diffusion of induced currents during EM transmitter on-time

In this abstract, we calculate the current density during the on-time of a half-sine waveform EM system. Because current is continually regenerated at surface, the classic smoke-ring appearance of current induced in the ground is distorted. We show that current density during the on-time is concentrated at surface compared to the off-time and conclude that on-time measurements should be relatively more sensitive to near-surface features.