Ring-core fluxgate magnetometers for use as observatory variometers

Narod, B. Barry; Bennest, J. R.

doi:10.1016/0031-9201(90)90205-c

Cited by 38 publications

(31 citation statements)

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“…Narod and Bennest, 1990) to sense the fluxgate signal at twice the sensor drive frequency (2 f ) are not required in this design. In the prototype, the sensor is directly digitised by sampling the instantaneous output from the sensor.…”

Section: Direct Digitisationmentioning

confidence: 99%

“…Narod and Bennest, 1990); however, it has been missing in previous digital designs. The technique requires a low-pass reconstruction filter on the digital feedback to avoid clipping the transconductance feedback amplifier with the comparatively large switching signal from the PWM.…”

Section: A Voltage-to-current Converter To Drive the Feedback Coilmentioning

confidence: 99%

“…Narod and Bennest, 1990). The NGL design was previously modified for low-radiation space applications as the magnetic field instrument (MGF) in the CSA's enhanced Polar Outflow Probe (ePOP) payload on the CAScade, Smallsat and IOnospheric Polar Explorer (CAS-SIOPE) satellite (Wallis et al, 2006).…”

Section: Introduction and Applicationmentioning

confidence: 99%

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A radiation hardened digital fluxgate magnetometer for space applications

Miles

Bennest²,

Mann

et al. 2013

Geosci. Instrum. Method. Data Syst.

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Abstract. Space-based measurements of Earth's magnetic field are required to understand the plasma processes responsible for energising particles in the Van Allen radiation belts and influencing space weather. This paper describes a prototype fluxgate magnetometer instrument developed for the proposed Canadian Space Agency's (CSA) Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) mission and which has applications in other space and suborbital applications. The magnetometer is designed to survive and operate in the harsh environment of Earth's radiation belts and measure low-frequency magnetic waves, the magnetic signatures of current systems, and the static background magnetic field. The new instrument offers improved science data compared to its predecessors through two key design changes: direct digitisation of the sensor and digital feedback from two cascaded pulse-width modulators combined with analog temperature compensation. These provide an increase in measurement bandwidth up to 450 Hz with the potential to extend to at least 1500 Hz. The instrument can resolve 8 pT on a 65 000 nT field with a magnetic noise of less than 10 pT/ √Hz at 1 Hz. This performance is comparable with other recent digital fluxgates for space applications, most of which use some form of sigma-delta ( ) modulation for feedback and omit analog temperature compensation. The prototype instrument was successfully tested and calibrated at the Natural Resources Canada Geomagnetics Laboratory.

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Section: Direct Digitisationmentioning

confidence: 99%

Section: A Voltage-to-current Converter To Drive the Feedback Coilmentioning

confidence: 99%

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A radiation hardened digital fluxgate magnetometer for space applications

Miles

Bennest²,

Mann

et al. 2013

Geosci. Instrum. Method. Data Syst.

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“…(Narod and Bennest, 1990), with three ring-core sensors mounted orthogonally on a common base (Fig. 4).…”

Section: Electronic Temperature Compensationmentioning

confidence: 99%

“…The specific materials used in sensor construction are often not provided in instrument publications. However, MACOR is explicitly mentioned or known to be used in the NASA MAGSAT satellite (Acuña et al, 1978); the S100, STE, and PC104 observatory magnetometers developed by Narod Geophysics Ltd. (Narod and Bennest, 1990); both the Canadian CARISMA ground network (Mann et al, 2008) and the US EMScope magnetotelluric network (Schultz, 2009); the Danish Oersted satellite (Nielsen et al, 1995); the miniaturised SMILE instrument (Forslund et al, 2007); the Vector Fluxgate Magnetometer (VMAG) for the Demonstration and Science Experiment program (Moldwin, 2010); a prototype radiation tolerant fluxgate (Miles et al, 2013); and the Canadian Space Agency Cassiope/e-POP satellite (Wallis et al, 2015). Unfortunately, MACOR is expensive, difficult to machine, and brittle.…”

Section: Introductionmentioning

confidence: 99%

The effect of winding and core support material on the thermal gain dependence of a fluxgate magnetometer sensor

Miles

Mann

Kale

et al. 2017

Geosci. Instrum. Method. Data Syst.

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Abstract. Fluxgate magnetometers are an important tool in geophysics and space physics but are typically sensitive to variations in sensor temperature. Changes in instrumental gain with temperature, thermal gain dependence, are thought to be predominantly due to changes in the geometry of the wire coils that sense the magnetic field and/or provide magnetic feedback. Scientific fluxgate magnetometers typically employ some form of temperature compensation and support and constrain wire sense coils with bobbins constructed from materials such as MACOR machinable ceramic (Corning Inc.) which are selected for their ultra-low thermal deformation rather than for robustness, cost, or ease of manufacturing. We present laboratory results comparing the performance of six geometrically and electrically matched fluxgate sensors in which the material used to support the windings and for the base of the sensor is varied. We use a novel, lowcost thermal calibration procedure based on a controlled sinusoidal magnetic source and quantitative spectral analysis to measure the thermal gain dependence of fluxgate magnetometer sensors at the ppm • C −1 level in a typical magnetically noisy university laboratory environment. We compare the thermal gain dependence of sensors built from MA-COR, polyetheretherketone (PEEK) engineering plastic (virgin, 30 % glass filled and 30 % carbon filled), and acetal to examine the trade between the thermal properties of the material, the impact on the thermal gain dependence of the fluxgate, and the cost and ease of manufacture. We find that thermal gain dependence of the sensor varies as one half of the material properties of the bobbin supporting the wire sense coils rather than being directly related as has been historically thought. An experimental sensor constructed from 30 % glass-filled PEEK (21.6 ppm • C −1 ) had a thermal gain dependence within 5 ppm • C −1 of a traditional sensor constructed from MACOR ceramic (8.1 ppm • C −1 ). If a modest increase in thermal dependence can be tolerated or compensated, then 30 % glass-filled PEEK is a good candidate for future fluxgate sensors as it is more economical, easier to machine, lighter, and more robust than MACOR.

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A miniature, low‐power scientific fluxgate magnetometer: A stepping‐stone to cube‐satellite constellation missions

et al. 2016

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Difficulty in making low noise magnetic measurements is a significant challenge to the use of cube‐satellite (CubeSat) platforms for scientific constellation class missions to study the magnetosphere. Sufficient resolution is required to resolve three‐dimensional spatiotemporal structures of the magnetic field variations accompanying both waves and current systems of the nonuniform plasmas controlling dynamic magnetosphere‐ionosphere coupling. This paper describes the design, validation, and test of a flight‐ready, miniature, low‐mass, low‐power, and low‐magnetic noise boom‐mounted fluxgate magnetometer for CubeSat applications. The miniature instrument achieves a magnetic noise floor of 150–200 pT/√Hz at 1 Hz, consumes 400 mW of power, has a mass of 121 g (sensor and boom), stows on the hull, and deploys on a 60 cm boom from a three‐unit CubeSat reducing the noise from the onboard reaction wheel to less than 1.5 nT at the sensor. The instrument's capabilities will be demonstrated and validated in space in late 2016 following the launch of the University of Alberta Ex‐Alta 1 CubeSat, part of the QB50 constellation mission. We illustrate the potential scientific returns and utility of using a CubeSats carrying such fluxgate magnetometers to constitute a magnetospheric constellation using example data from the low‐Earth orbit European Space Agency Swarm mission. Swarm data reveal significant changes in the spatiotemporal characteristics of the magnetic fields in the coupled magnetosphere‐ionosphere system, even when the spacecraft are separated by only approximately 10 s along track and approximately 1.4° in longitude.

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Ring-core fluxgate magnetometers for use as observatory variometers

Cited by 38 publications

References 1 publication

A radiation hardened digital fluxgate magnetometer for space applications

A radiation hardened digital fluxgate magnetometer for space applications

The effect of winding and core support material on the thermal gain dependence of a fluxgate magnetometer sensor

A miniature, low‐power scientific fluxgate magnetometer: A stepping‐stone to cube‐satellite constellation missions

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