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Design and test of the parallel ultra-small transmitter loop used in the transient electromagnetic method |
WU Bei-Chen( ), PAN Yang-Run-Yi, CHENG Jiu-Long( ), WANG Hui, YAO Di, PANG Xiao-Yin |
School of Geosciences & Surveying Engineering, Chinese University of Mining and Technology (Beijing), Beijing 100083, China |
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Abstract In the shallow or mine prospecting using the transient electromagnetic method (TEM), the transmitting magnetic moment is limited by the limited supply voltage of the transmitting system, and the stray inductance of the transmitter loop causes a long turn-off time. To solve these problems, this study designed a parallel transmitter loop of ultra-small coils used in TEM. Using these coils, the transmitting magnetic moment can be increased by the parallel connection of the coils, and the turn-off time can be reduced by additional resistance. The equivalent circuit models of the conventional transmitter coils and the parallel transmitter coils were established and analyzed theoretically. Moreover, the comparative test between the parallel transmitter coils and the conventional transmitter coils were carried out. The results show that the parallel transmitter coils can effectively increase the magnetic moment and reduce the turn-off time. Therefore, this design is greatly significant for reducing the blind area and increasing the prospecting depth in shallow or mine prospecting using TEM.
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Received: 05 August 2021
Published: 17 August 2022
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Corresponding Authors:
CHENG Jiu-Long
E-mail: bei_chen_wu@163.com;JLCheng@126.com
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Equivalent circuit of the multi-turn loop
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Equivalent circuit of the common transmitter loop
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Schematic diagram of parallel transmission loop
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Equivalent circuit of the parallel transmitter loop
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Equivalent circuit of the parallel transmitter loop with added resistance
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Test scenario
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Turn-off current waveform and comparison
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子回线参数 | 一般发射回 线发射电流 值I0/A | 并联式发射 回线发射电 流值 /A | I0/ | L/mH | R/Ω | 1.58 | 10.34 | 1.043 | 1.910 | 55% | 7.98 | 6.30 | 1.776 | 3.065 | 58% | 7.98 | 5.30 | 2.064 | 3.601 | 57% | 1.58 | 11.52 | 0.953 | 1.782 | 53% |
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Comparison of initial current of different transmitting loops
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Turn-off current waveform and comparison
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子回线参数 | 一般发射回 线关断时间 t/μs | 并联式发射 回线关断时 间t'/μs | t/t' | L/mH | R/Ω | 1.58 | 5.76 | 201 | 101 | 50% | 1.58 | 4.17 | 221 | 115 | 52% | 7.98 | 3.15 | 2272 | 1051 | 46% | 7.98 | 2.65 | 2641 | 1239 | 47% |
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Comparison of turn-off time of different transmitting loops
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