Field trials using HTS SQUID magnetometers for ground-based and airborne geophysical applications

Foley, C. P.; Leslie, Keith; Binks, R. A.; Lewis, Chris; Murray, W.; Sloggett, G. J.; Lam, Siu Shu Eddie; Sankrithyan, B; Savvides, N.; Katzaros, A.; Müller, K.‐H.; Mitchell, E.E.; Pollock, J. T. A.; Lee, J.; Dart, D.L.; Barrow, Rosemary; Asten, Michael; Maddever, Arthur; Panjkovic, Goran; Downey, M.; Hoffman, C.R.; Turner, Robert

doi:10.1109/77.783852

Cited by 61 publications

(29 citation statements)

References 13 publications

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“…They are therefore variometers rather than magnetometers, but they are vector sensors since only changes perpendicular to the loop are detected [12][13][14]. CSIRO's GETMAG system [1] is an integrated package of three rotating single-axial gradiometer sensors in an umbrella arrangement.…”

Section: Model Studymentioning

confidence: 99%

3D Inversion of SQUID Magnetic Tensor Data

Zhdanov¹,

Cai²,

Wilson³

2012

J Geol Geosci

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Developments in SQUID-based technology have enabled direct measurement of magnetic tensor data for geophysical exploration. For quantitative interpretation, we introduce 3D regularized inversion for magnetic tensor data. For mineral exploration-scale targets, our model studies show that magnetic tensor data have significantly improved resolution compared to magnetic vector data for the same model. We present a case study for the 3D regularized inversion of magnetic tensor data acquired over a magnetite skarn at Tallawang, Australia. The results obtained from our 3D regularized inversion agree very well with the known geology of the area.

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Section: Model Studymentioning

confidence: 99%

3D Inversion of SQUID Magnetic Tensor Data

Zhdanov¹,

Cai²,

Wilson³

2012

J Geol Geosci

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“…The authors have recently fabricated an airborne superconducting magnetic detector for detection of magnetic dipole targets in sunken ships and have reported its high sensitivity in a real environment on board an aircraft [810]. High-temperature SQUIDs operating at liquid nitrogen temperature, with an easy cooling process, have been developed and applied to subsurface research and nondestructive testing [11,12].…”

Section: Introductionmentioning

confidence: 99%

A study on direction‐of‐arrival estimation methods using cosθ amplitude response antenna

Ishihara

Takada

Araki

et al. 2002

Electron. Comm. Jpn. Pt. I

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SUMMARYAt present, when the direction of arrival of a lowfrequency electromagnetic wave such as one in the HF band is measured, loop antennas are used. However, in lowfrequency measurement such as is used in underwater communications, subsurface resource detection, volcanic activity observation, and natural electromagnetic wave observation, the receiving power sensitivity decreases as the frequency is decreased. The purpose of this paper is to use a SQUID (Superconducting QUantum Interference Device), known as an ultrasensitive magnetic sensor, for construction of a small magnetic antenna for estimating the direction of arrival of low-frequency electromagnetic waves. As a first step, the antenna configuration and direction of arrival estimation method shown below are proposed.• As a low-frequency broadband antenna with an amplitude response type, we consider a SQUID array, which has a cosθ mode vector consisting of SQUID elements on a circle with a small radius, which is negligible in comparison with the wavelength of the incident wave.• For an antenna with a real-valued cosθ mode vector, we consider a direction-of-arrival estimation method within the framework of the estimation principle of ES -PRIT and MUSIC, known as high-resolution direction-ofarrival estimation methods, and derive an estimation method. The obtained estimation method is shown to be ultimately reducible to a simple estimation equation for deriving the phase difference between the 1st and 1st fundamental waves after beam subspace transformation of the correlation function without eigenfunction expansion. By computer simulation, it is shown that an estimation accuracy of 0.2 to 2° is obtained by this estimation equation for the finitely many elements and snapshots that are actually anticipated.

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“…Therefore, we propose that the crossover occurs between the third and the fourth remnant transient. We confine ourselves to considering the case that the single pulse transient be described by (5) Then, in the limit of a large number of averages, , we can express the stacking sum (1) as (6) With the generalized Riemann Zeta Function,…”

Section: The Appearance Of Sign Reversalmentioning

confidence: 99%

“…In the past decade, several HTS SQUID magnetometer systems for ground-based and airborne geophysical TEM exploration have been developed and their reliability has been proven in numerous field trials [4], [6]- [9]. Two peculiarities show up rather frequently in SQUID TEM recordings in the in-loop configuration [4], albeit they are not observed in corresponding induction coil data: the 'frequency dependence' of the stacked time transients on the repetition frequency of the transmitter, and the appearance of so-called "sign reversals," the crossover of the stacked time transients to negative values.…”

mentioning

confidence: 99%

Appearance of Sign Reversal in Geophysical Transient Electromagnetics With a SQUID Due to Stacking

Krause

Panaitov

Zhang

et al. 2005

IEEE Trans. Appl. Supercond.

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. Although the step function inductive response for many TEM targets decays monotonically and is positive at all times, instances of sign reversal do occur. We postulate that this sign reversal is due to the typical bipolar waveform of the TEM transmitter and the stacking procedure. In this contribution, we systematically extend our analysis to binary and ternary power-law expressions for the step function response, modeling measured responses for typical ground structures. The conditions are determined under which sign reversals appear. It is shown that the effect occurs mainly in the case where a shallow slope response is followed by a rapidly decaying response at late times. Such a signal is typically measured on a resistive overburden over a conducting medium. As an example, data are presented from a location where a sign reversal was measured with a SQUID whereas none was found in the coil data. A deconvolution procedure for determining the single pulse response from measured SQUID data is proposed.

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Field trials using HTS SQUID magnetometers for ground-based and airborne geophysical applications

Cited by 61 publications

References 13 publications

3D Inversion of SQUID Magnetic Tensor Data

3D Inversion of SQUID Magnetic Tensor Data

A study on direction‐of‐arrival estimation methods using cosθ amplitude response antenna

Appearance of Sign Reversal in Geophysical Transient Electromagnetics With a SQUID Due to Stacking

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