Fast turning on-off technology of transmitting current waveform in transient electromagnetic exploration

• Published in: Journal of applied geophysics Vol. 241; p. 105789
• Main Authors: Zhen, Qihui, Di, Qingyun, Wang, Zhongxin, Xue, Guoqiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2025
• Subjects: Artificial source; Current fast turning on-off; Electromagnetic exploration; Inductive load; Transmitter; Transmitter; Artificial source; Electromagnetic exploration; Current fast turning on-off; Inductive load
• ISSN: 0926-9851
• DOI: 10.1016/j.jappgeo.2025.105789

In transient electromagnetic (TEM) exploration, the selection of transmitting waveforms has a critical impact on both the detection depth and target resolution. A crucial requirement for TEM methodologies is the transmitter's ability to achieve rapid current turn-off, faster turning off lead to results that more closely approximate theoretical models. However, conventional TEM transmitters are significantly constrained by load inductance, typically exhibiting turn-off delays ranging from tens to hundreds of microseconds. This limitation poses a critical challenge to early-time data acquisition. To address this fundamental bottleneck, this paper introduces an innovative fast current turn-on/off technology specifically designed for highly inductive loads, which is applicable to both grounded and loop source configurations. Experimental results demonstrate excellent consistency with theoretical predictions, with the current turn-off time controllable within a range of 10–20 μs. The developed technique empowers precise control and meticulous adjustment of the current turn-off timing. By doing so, it delivers optimal excitation to the field source in transient electromagnetic exploration, thereby streamlining the collection of more comprehensive detection data •The on-off time of the current performance has improved by more then 70 % to 80 %.•The number of series-connected rapid switching units can be optimized according to current turn-off time requirements.•This technology delivers enhanced field excitation capabilities for transient electromagnetic exploration.