Electromagnetic Detection System with Magnetic Dipole Source for Near-Surface Detection

Abstract

This paper proposes a nondestructive, separate transmitter-receiver (TX-RX) electromagnetic measurement system for near-surface detection. Different from the traditional dual-coil integrated design, the proposed transient electromagnetic (TEM) system performs shallow subsurface detection using independent TX coil and movable RX coils. This configuration requires a large primary field so that the far-away secondary field is able to generate reliably induced voltages. To achieve this goal, a bipolar current-pulsed power supply (BCPPS) with a late resonant charging strategy is designed to produce a sufficiently large magnetic moment for the exciting coil with low source interference. The magnetic dipole source (MDS) with a large proportion of weight is separated from the field observation device and does not need to be dragged or transported during the detection process. This setup lowers the weight of the scanning device to 3 kg and greatly improves the measurement efficiency. The results of the laboratory test verify the effectiveness of the separate MDS and RX module system. Field experimental detection further demonstrates that the proposed system can realize highly efficient and shallow surface detection within a 200 m range of the MDS device.

Hydrogeological Investigation of a Goaf and Subsidence Area Based on a Ground-to-Air Transient Electromagnetic Sounding Method

“…The ground-to-air transient electromagnetic method involves placing the electrical source or loop source on the ground to induce excitation, while utilizing an airborne device to capture the corresponding electromagnetic response. The proposed method exhibits several advantages over conventional ground or aerial geophysical exploration techniques, including a highly responsive, well-conductive electrolyte; superior detection efficiency; minimal blind spots in detection; a significant depth of penetration; robust antiinterference capabilities; non-contact detection capability; cost-effectiveness; and enhanced safety [37][38][39][40].…”