Development of TDEM Data Acquisition System Based on High <I>T<SUB>c</SUB></I> SQUIDs for Mineral Exploration

Hajime OTA; Tatsuoki NAGAISHI; Eiichi ARAI

doi:10.1093/ietele/e88-c.2.192

Development of TDEM Data Acquisition System Based on High T_c SQUIDs for Mineral Exploration

Hajime OTA, Tatsuoki NAGAISHI, Eiichi ARAI

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The Time Domain Electromagnetic Method (TDEM) survey is one of the several geophysical exploration methods. In the conventional TDEM survey, an induction coil is used as the magnetometer. However, the measurement depth is limited to about 500 m. Using high T_c SQUIDs, there are expectations of large bandwidth and high sensitivity for the TDEM. We developed the high T_c SQUID TDEM system. We have reduced the system noise by developing a 20 mm20 mm step-edge type direct coupled SQUID and a low noise direct readout flux locked loop (FLL) circuit. We have also improved the slew rate, optimizing the parameter of the FLL circuit. Consequently, the system noise of less than 0.2 pT/Hz^1/2 at 1 kHz was achieved in the earth's magnetic field. The slew rate was 7.3 mT/sec. We conducted field trials and confirmed that the TDEM using high T_c SQUIDs obtains information of deeper region with high precision compared with the TDEM using induction coils.

Publication: IEICE TRANSACTIONS on Electronics Vol.E88-C No.2 pp.192-197

Publication Date: 2005/02/01

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DOI: 10.1093/ietele/e88-c.2.192

Type of Manuscript: Special Section PAPER (Special Section on Superconducting Electronic Devices and Their Applications)

Category: SQUIDs

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Hajime OTA, Tatsuoki NAGAISHI, Eiichi ARAI, "Development of TDEM Data Acquisition System Based on High Tc SQUIDs for Mineral Exploration" in IEICE TRANSACTIONS on Electronics, vol. E88-C, no. 2, pp. 192-197, February 2005, doi: 10.1093/ietele/e88-c.2.192.
Abstract: The Time Domain Electromagnetic Method (TDEM) survey is one of the several geophysical exploration methods. In the conventional TDEM survey, an induction coil is used as the magnetometer. However, the measurement depth is limited to about 500 m. Using high T_c SQUIDs, there are expectations of large bandwidth and high sensitivity for the TDEM. We developed the high T_c SQUID TDEM system. We have reduced the system noise by developing a 20 mm20 mm step-edge type direct coupled SQUID and a low noise direct readout flux locked loop (FLL) circuit. We have also improved the slew rate, optimizing the parameter of the FLL circuit. Consequently, the system noise of less than 0.2 pT/Hz^1/2 at 1 kHz was achieved in the earth's magnetic field. The slew rate was 7.3 mT/sec. We conducted field trials and confirmed that the TDEM using high T_c SQUIDs obtains information of deeper region with high precision compared with the TDEM using induction coils.
URL: https://globals.ieice.org/en_transactions/electronics/10.1093/ietele/e88-c.2.192/_p

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@ARTICLE{e88-c_2_192,
author={Hajime OTA, Tatsuoki NAGAISHI, Eiichi ARAI, },
journal={IEICE TRANSACTIONS on Electronics},
title={Development of TDEM Data Acquisition System Based on High Tc SQUIDs for Mineral Exploration},
year={2005},
volume={E88-C},
number={2},
pages={192-197},
abstract={The Time Domain Electromagnetic Method (TDEM) survey is one of the several geophysical exploration methods. In the conventional TDEM survey, an induction coil is used as the magnetometer. However, the measurement depth is limited to about 500 m. Using high T_c SQUIDs, there are expectations of large bandwidth and high sensitivity for the TDEM. We developed the high T_c SQUID TDEM system. We have reduced the system noise by developing a 20 mm20 mm step-edge type direct coupled SQUID and a low noise direct readout flux locked loop (FLL) circuit. We have also improved the slew rate, optimizing the parameter of the FLL circuit. Consequently, the system noise of less than 0.2 pT/Hz^1/2 at 1 kHz was achieved in the earth's magnetic field. The slew rate was 7.3 mT/sec. We conducted field trials and confirmed that the TDEM using high T_c SQUIDs obtains information of deeper region with high precision compared with the TDEM using induction coils.},
keywords={},
doi={10.1093/ietele/e88-c.2.192},
ISSN={},
month={February},}

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TY - JOUR
TI - Development of TDEM Data Acquisition System Based on High Tc SQUIDs for Mineral Exploration
T2 - IEICE TRANSACTIONS on Electronics
SP - 192
EP - 197
AU - Hajime OTA
AU - Tatsuoki NAGAISHI
AU - Eiichi ARAI
PY - 2005
DO - 10.1093/ietele/e88-c.2.192
JO - IEICE TRANSACTIONS on Electronics
SN -
VL - E88-C
IS - 2
JA - IEICE TRANSACTIONS on Electronics
Y1 - February 2005
AB - The Time Domain Electromagnetic Method (TDEM) survey is one of the several geophysical exploration methods. In the conventional TDEM survey, an induction coil is used as the magnetometer. However, the measurement depth is limited to about 500 m. Using high T_c SQUIDs, there are expectations of large bandwidth and high sensitivity for the TDEM. We developed the high T_c SQUID TDEM system. We have reduced the system noise by developing a 20 mm20 mm step-edge type direct coupled SQUID and a low noise direct readout flux locked loop (FLL) circuit. We have also improved the slew rate, optimizing the parameter of the FLL circuit. Consequently, the system noise of less than 0.2 pT/Hz^1/2 at 1 kHz was achieved in the earth's magnetic field. The slew rate was 7.3 mT/sec. We conducted field trials and confirmed that the TDEM using high T_c SQUIDs obtains information of deeper region with high precision compared with the TDEM using induction coils.
ER -