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| Titel |
MEMS-based gradiometer for the complete characterization of Martian magnetic environment |
| VerfasserIn |
Jose Luis Mesa, David Ciudad, Michael E. McHenry, Claudio Aroca, Marina Díaz-Michelena |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072036
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| Zusammenfassung |
| The in-situ determination of the Martian magnetic field is one of the most important and
ambitious objectives in Mars exploration, because its implications in paleomagnetism,
tectonics and mineral determination.
To place sensors on Mars is a complicated task, due to the extreme conditions of the
planet surface and also because of the relative low budget devoted to this kind of
instrument: low power, mass, volume and the need to operate in a magnetically noise
environment.
A complete and accurate measurement of the magnetic environment includes the
determination of both magnitude and gradient of the magnetic field (B). There are many
developments of magnetometers with the characteristics mentioned before [2], but the
question about gradient is not that well solved and most gradient sensors are based on a
couple of magnetometers separated a certain distance [2, 3].
The aim of this abstract is to introduce a new MEMS based robust gradiometer for the
point measurement of the field gradient with the ultimate goal to perform in situ measurement
on Mars and shed some light in the magnetic anomalies explanation of the Red
Planet.
Since in some conditions-ïB = 0, we assume knowing six of the nine components is
sufficient to reconstruct entirely the magnetic field gradient. The device proposed
consists of a set of six cantilevers to measure these six components (with resolution
in the order of 1 nT/mm) combined either with another miniaturized and more
accurate magnetometer (with resolution below the nT) for the measurement of the field
vector.
Every component system consists of a cantilever with an appropriate geometry, an
excitation coil and a mechanism to generate a field gradient. The cantilevers are made of
piezoelectric material (bimorph, with two piezoelectric layers) covered by a soft
ferromagnetic material (of Iron-Nickel base). Is explained below the working principle for
one component.
When the excitation system generates an alternating magnetic field (enough to saturate)
along the width of the cantilever, the ferromagnetic material is alternatively saturated in both
directions along the cantilever’s width.
Under the presence of a magnetic field gradient in the normal direction to the
plane of the cantilever, the ferromagnetic material experiments a force, making the
cantilever vibrate. This vibration generates an electric signal, given that when the
cantilever vibrates, the piezoelectric layers stretches and contracts, so it sets a voltage
difference.
The current system with dimensions in the order of mm is run at its resonant frequency. In
the presence of an external magnetic field gradient, the vibration frequency changes. The
external gradient can be easily measured by means of the measurement of the frequency
shift.
References:
[1] Acuña, M.H.: Space-based magnetometers, Rev. Sci. Instrum., 73, 3717-3736, doi:
10.1063/1.1510570, Nov 2002.
[2] Merayo, J.M.G.; Brauer, P.; Primdahl, F.: Triaxial fluxgate gradiometer of high
stability and linearity, Sensor Actuat A-Phys., 120, 71-77, doi: 10.1016/j.sna.2004.11.014,
Apr 2005.
[3] Lucas, I.; Michelena, M.D.;del Real, R.P.; de Manuel, V.; Plaza, J.A. 2; Duch, M.;
Esteve, J; Guerrero, H.: A New Single-Sensor Magnetic Field Gradiometer, Sens. Lett., 7,
563-570, doi: 10.1166/sl.2009.1110, Aug 2009. |
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