String magnetic gradiometer system: recent airborne trials

McRae, Wayne; Veryaskin, Alexey V.; Greager, David; Li, Ju; Blair, David; Chin, E.; Dumas, J. C.; Liu, Ben

doi:10.1190/1.1845297

Cited by 11 publications

(11 citation statements)

References 4 publications

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“…This compares with seismic noise of 3 × 10 −6 m/(s 2 √ Hz) on the ground [27] and engine noise of 3 × 10 −2 m/(s 2 √ Hz) on a survey aircraft [13]. The reduction of vibration noise by 9 orders of magnitude more than compensates for the greater vibration at lower frequencies.…”

Section: Vibration Noisementioning

confidence: 86%

Direct string magnetic gradiometer for space applications

Sunderland¹,

Veryaskin²,

McRae³

et al. 2008

Sensors and Actuators A: Physical

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a b s t r a c tRecently, a novel direct string magnetic gradiometer (DSMG) has been developed, where a vibrating wire, driven by an AC current, is used as a single sensitive element. It is designed to directly measure the local offdiagonal components of the magnetic gradient tensor, Bxz, Byz and Bxy, provided the distance to an object creating magnetic anomalies is much larger than the length of the string. This requirement is well satisfied in space, if the sensor is deployed from a satellite platform orbiting near the planet under surveillance. Current instruments operating at 1 kPa pressure achieve sensitivity of 4 × 10 −10 T/(m √ Hz) in the band 0.0025-0.3 Hz. In this paper we show that proposed modifications to the current gradiometer design, specifically aimed at the deployment in space, could have a magnetic gradient sensitivity better than 10 −13 T/(m √ Hz) in the frequency range of interest for specific missions both for fundamental research and for such applications as geophysical exploration on Mars and other solar system planets. Also, by combining a few single-axis magnetic gradiometer modules, it is possible to deploy a full tensor magnetic gradiometer.

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Section: Vibration Noisementioning

confidence: 86%

Direct string magnetic gradiometer for space applications

Sunderland¹,

Veryaskin²,

McRae³

et al. 2008

Sensors and Actuators A: Physical

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“…Project AMATI, so named in honour of the famous violin maker Nicolo Amati, is focussed on developing a direct string Magnetic Gradiometer capable of measuring cross-diagonal components of the magnetic gradient tensor (Veryaskin, 2000;Veryaskin, 2001;McRae et. al., 2004).…”

Section: Methods and Resultsmentioning

confidence: 99%

Description of and Results From a Novel Direct Magnetic Gradiometer

Golden¹,

McRae²,

Sunderland

et al. 2007

ASEG Extended Abstracts

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“…Other proposed technologies include a stiff metallic string carrying an AC current tuned to the second eigenmode of mechanical vibration, which is sensitive to an off-diagonal term of the gradient tensor (Veryaskin, 2001;McRae et al, 2004;Sunderland et al, 2009). Although this technique only measures a single tensor component, the full gradient tensor could, in principle, be obtained from an array of differently oriented string sensors.…”

Section: Recent Developments In Magnetic Tensor Gradiometer Systemsmentioning

confidence: 99%

Corrigendum to:New methods for interpretation of magnetic vector and gradient tensor data I: eigenvector analysis and the normalised source strength

Clark

2014

Exploration Geophysics

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Acquisition of magnetic gradient tensor data is likely to become routine in the near future. New methods for inverting gradient tensor surveys to obtain source parameters have been developed for several elementary, but useful, models. These include point dipole (sphere), vertical line of dipoles (narrow vertical pipe), line of dipoles (horizontal cylinder), thin dipping sheet, and contact models. A key simplification is the use of eigenvalues and associated eigenvectors of the tensor. The normalised source strength (NSS), calculated from the eigenvalues, is a particularly useful rotational invariant that peaks directly over 3D compact sources, 2D compact sources, thin sheets and contacts, and is independent of magnetisation direction. In combination the NSS and its vector gradient determine source locations uniquely. NSS analysis can be extended to other useful models, such as vertical pipes, by calculating eigenvalues of the vertical derivative of the gradient tensor. Inversion based on the vector gradient of the NSS over the Tallawang magnetite deposit obtained good agreement between the inferred geometry of the tabular magnetite skarn body and drill hole intersections. Besides the geological applications, the algorithms for the dipole model are readily applicable to the detection, location and characterisation (DLC) of magnetic objects, such as naval mines, unexploded ordnance, shipwrecks, archaeological artefacts, and buried drums.

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String magnetic gradiometer system: recent airborne trials

Cited by 11 publications

References 4 publications

Direct string magnetic gradiometer for space applications

Direct string magnetic gradiometer for space applications

Description of and Results From a Novel Direct Magnetic Gradiometer

Corrigendum to:New methods for interpretation of magnetic vector and gradient tensor data I: eigenvector analysis and the normalised source strength

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