scholarly journals The Fluxgate Magnetometer of the Low Orbit Pearl Satellites  (LOPS): overview of in-flight performance and initial results 

2021 ◽  
Author(s):  
Ye Zhu ◽  
Aimin Du ◽  
Hao Luo ◽  
Donghai Qiao ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current System ◽  
Equatorial Electrojet ◽  
Field Measurements ◽  
Stray Field ◽  
Fluxgate Magnetometer ◽  
General Description ◽  
Flight Performance ◽  
Spatial Coverage ◽  
Initial Results

Abstract. The Low Orbit Pearl Satellite series consists of six constellations, with each constellation consisting of three identical micro-satellites which line up just like a string of pearls. The first constellation of three satellites were launched on September 29, 2017, with an inclination of ~ 35.5° and ~ 600 km altitude. Each satellite is equipped with three identical Fluxgate Magnetometers (FGM), which measure the in-situ magnetic field and its low frequency fluctuations in the Earth’s low altitude orbit. The triple sensor configuration enables separation of stray field effects generated by the spacecraft from the ambient magnetic field [e.g. Zhang et al., 2006]. This paper gives a general description of the magnetometer about the instrument design, calibration before launch, in flight calibration, as well as the in-flight performance and initial results. Unprecedented spatial coverage resolution of the magnetic field measurements allow for investigating the dynamic processes and electric currents of ionosphere and magnetosphere, especially for the ring current and equatorial electrojet (EEJ) during both geomagnetic quiet conditions and storms. It could be important for studying the method to separate their contributions of the M-I current system.

scholarly journals The fluxgate magnetometer of the Low Orbit Pearl Satellites (LOPS): overview of in-flight performance and initial results

2021 ◽  
Vol 10 (2) ◽  
pp. 227-243
Author(s):  
Ye Zhu ◽  
Aimin Du ◽  
Hao Luo ◽  
Donghai Qiao ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current System ◽  
Field Measurements ◽  
Stray Field ◽  
Fluxgate Magnetometer ◽  
General Description ◽  
Flight Performance ◽  
Spatial Coverage ◽  
Magnetic Field Measurements ◽  
Initial Results

Abstract. The Low Orbit Pearl Satellite series consists of six constellations, with each constellation consisting of three identical microsatellites that line up just like a string of pearls. The first constellation of three satellites were launched on 29 September 2017, with an inclination of ∼ 35.5∘ and ∼ 600 km altitude. Each satellite is equipped with three identical fluxgate magnetometers that measure the in situ magnetic field and its low-frequency fluctuations in the Earth's low-altitude orbit. The triple sensor configuration enables separation of stray field effects generated by the spacecraft from the ambient magnetic field (e.g., Zhang et al., 2006). This paper gives a general description of the magnetometer including the instrument design, calibration before launch, in-flight calibration, in-flight performance, and initial results. Unprecedented spatial coverage resolution of the magnetic field measurements allow for the investigation of the dynamic processes and electric currents of the ionosphere and magnetosphere, especially for the ring current and equatorial electrojet during both quiet geomagnetic conditions and storms. Magnetic field measurements from LOPS could be important for studying the method to separate their contributions of the Magnetosphere-Ionosphere (M-I) current system.

scholarly journals Multi-point ground-based ULF magnetic field observations in Europe during seismic active periods in 2004 and 2005

2008 ◽  
Vol 8 (3) ◽  
pp. 501-507 ◽  
Author(s):  
G. Prattes ◽  
K. Schwingenschuh ◽  
H. U. Eichelberger ◽  
W. Magnes ◽  
M. Boudjada ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Seismic Activity ◽  
Magnetic Field Intensity ◽  
Field Measurements ◽  
Fluxgate Magnetometer ◽  
Vertical Magnetic Field ◽  
Earthquake Epicenter ◽  
Electromagnetic Noise ◽  
Horizontal Magnetic Field

Abstract. We present the results of ground-based Ultra Low Frequency (ULF) magnetic field measurements observed from June to August 2004 during the Bovec earthquake on 12 July 2004. Further we give information about the seismic activity in the local observatory region for an extended time span 2004 and 2005. ULF magnetic field data are provided by the South European Geomagnetic Array (SEGMA) where the experience and heritage from the CHInese MAGnetometer (CHIMAG) fluxgate magnetometer comes to application. The intensities of the horizontal H and vertical Z magnetic field and the polarization ratio R of the vertical and horizontal magnetic field intensity are analyzed taking into consideration three SEGMA observatories located at different close distances and directions from the earthquake epicenter. We observed a significant increase of high polarization ratios during strong seismic activity at the observatory nearest to the Bovec earthquake epicenter. Apart from indirect ionospheric effects electromagnetic noise could be emitted in the lithosphere due to tectonic effects in the earthquake focus region causing anomalies of the vertical magnetic field intensity. Assuming that the measured vertical magnetic field intensities are of lithospheric origin, we roughly estimate the amplitude of electromagnetic noise in the Earths crust considering an average electrical conductivity of <σ>=10−3 S/m and a certain distance of the observatory to the earthquake epicenter.

scholarly journals Low-noise permalloy ring cores for fluxgate magnetometers

2019 ◽  
Vol 8 (2) ◽  
pp. 227-240 ◽  
Author(s):  
David M. Miles ◽  
Miroslaw Ciurzynski ◽  
David Barona ◽  
B. Barry Narod ◽  
John R. Bennest ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Basic Research ◽  
Field Measurements ◽  
Low Noise ◽  
Space Physics ◽  
Local Magnetic Field ◽  
Fluxgate Magnetometer ◽  
Noise Performance ◽  
The 1960S ◽  
Or Gate

Abstract. Fluxgate magnetometers are important tools for geophysics and space physics, providing high-precision magnetic field measurements. Fluxgate magnetometer noise performance is typically limited by a ferromagnetic element that is periodically forced into magnetic saturation to modulate, or gate, the local magnetic field. The parameters that control the intrinsic magnetic noise of the ferromagnetic element remain poorly understood. Much of the basic research into producing low-noise fluxgate sensors was completed in the 1960s for military purposes and was never publicly released. Many modern fluxgates depend on legacy Infinetics S1000 ring cores that have been out of production since 1996 and for which there is no published manufacturing process. We present a manufacturing approach that can consistently produce fluxgate ring cores with a noise of ∼6–11 pT per square root hertz – comparable to many of the legacy Infinetics ring cores used worldwide today. As a result, we demonstrate that we have developed the capacity to produce the low-noise ring cores essential for high-quality, science-grade fluxgate instrumentation. This work has also revealed potential avenues for further improving performance, and further research into low-noise magnetic materials and fluxgate magnetometer sensors is underway.

scholarly journals How many solar wind data are sufficient for accurate fluxgate magnetometer offset determinations?

2019 ◽  
Vol 8 (2) ◽  
pp. 285-291 ◽  
Author(s):  
Ferdinand Plaschke
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Wind Data ◽  
Fluxgate Magnetometer ◽  
Time Intervals ◽  
Sensor Position ◽  
Magnetic Field Measurements ◽  
Wind Measurements ◽  
The Magnetic Field

Abstract. Accurate magnetic field measurements by fluxgate magnetometers onboard spacecraft require ground and regular in-flight calibration activities. Therewith, the parameters of a coupling matrix and an offset vector are adjusted; they are needed to transform raw magnetometer outputs into calibrated magnetic field measurements. The components of the offset vector are typically determined by analyzing Alfvénic fluctuations in the solar wind if solar wind measurements are available. These are characterized by changes in the field components, while the magnetic field modulus stays constant. In this paper, the following question is answered: how many solar wind data are sufficient for accurate fluxgate magnetometer offset determinations? It is found that approximately 40 h of solar wind data are sufficient to achieve offset accuracies of 0.2 nT, and about 20 h suffice for accuracies of 0.3 nT or better if the magnetometer offsets do not drift within these time intervals and if the spacecraft fields do not vary at the sensor position. Offset determinations with uncertainties lower than 0.1 nT, however, would require at least hundreds of hours of solar wind data.

scholarly journals Low-Noise Permalloy Ring-Cores for Fluxgate Magnetometers

2019 ◽  
Author(s):  
David M. Miles ◽  
Miroslaw Ciurzynski ◽  
David Barona ◽  
B. Barry Narod ◽  
John R. Bennest ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Basic Research ◽  
Field Measurements ◽  
Low Noise ◽  
Space Physics ◽  
Local Magnetic Field ◽  
Fluxgate Magnetometer ◽  
Noise Performance ◽  
The 1960S ◽  
Or Gate

Abstract. Fluxgate magnetometers are important tools for geophysics and space physics providing high precision magnetic field measurements. Fluxgate magnetometer noise performance is typically limited by a ferromagnetic element that is periodically forced into magnetic saturation to modulate, or gate, the local magnetic field. The parameters that control the intrinsic magnetic noise of the ferromagnetic element remain poorly understood. Much of the basic research into producing low-noise fluxgate sensors was completed in the 1960s for military purposes and was never publicly released. Many modern fluxgates depend on legacy Infinetics S1000 ring-cores that have been out of production since 1996 and for which there is no published manufacturing process. We present a manufacturing approach that can consistently produce fluxgate ring-cores with a noise of ∼6–11 pT per square root Hertz – comparable to many of the legacy Infinetics ring-cores used worldwide today. As a result, we demonstrate that we have developed the capacity to produce the low-noise ring-cores essential for high-quality, science-grade fluxgate instrumentation. This work has also revealed potential avenues for further improving performance, and further research into low-noise magnetic materials and fluxgate magnetometer sensors is underway.

scholarly journals Ionospheric currents estimated simultaneously from CHAMP satelliteand IMAGE ground-based magnetic field measurements: a statisticalstudy at auroral latitudes

2004 ◽  
Vol 22 (2) ◽  
pp. 417-430 ◽  
Author(s):  
P. Ritter ◽  
H. Lühr ◽  
A. Viljanen ◽  
O. Amm ◽  
A. Pulkkinen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Local Time ◽  
Hall Current ◽  
Activity Index ◽  
Current System ◽  
Current Model ◽  
Field Measurements ◽  
Magnetic Field Measurements ◽  
Current Densities ◽  
The Magnetic Field

Abstract. One important contribution to the magnetic field measured at satellite altitude and at ground level comes from the external currents. We used the total field data sampled by the Overhauser Magnetometer on CHAMP and the horizontal magnetic field measurements of the IMAGE ground-based magnetometer network to study the ionospheric Hall current system in the auroral regions. For the CHAMP data a current model consisting of a series of lines and placed at a height of 110km is fitted to the magnetic field signature sampled on the passage across the polar region. The derived current distributions depend, among others, on season and on the local time of the satellite track. At dawn/dusk the auroral electrojets can be detected most clearly in the auroral regions. Their intensity and location are evidently correlated with the A E activity index. For a period of almost two years the results obtained from space and the currents determined from ground-based observations are studied. For the full IMAGE station array a newly-developed method of spherical elementary current systems (SECS) is employed to compute the 2-D equivalent current distribution, which gives a detailed picture of an area covering latitudes 60° – 80° N and 10° – 30° E in the auroral region. Generally, the current estimates from satellite and ground are in good agreement. The results of this survey clearly show the average dependence of the auroral electrojet on season and local time. This is particularly true during periods of increased auroral activity. The correlation coefficient of the results is close to one in the region of sizeable ionospheric current densities. Also the ratio of the current densities, as determined from above and below the ionosphere, is close to unity. It is the first time that the method of Hall current estimate from a satellite has been validated quantitatively by ground-based observations. Among others, this result is of interest for magnetic main field modelling, since it demonstrates that ground-based observations can be used to predict electrojet signatures in satellite magnetic field scalar data. Key words. Ionosphere (auroral Ionosphere; electric fields and currents; ionosphere-magnetosphere interactions)

TESTS OF CRYOGENIC SQUID FOR GEOMAGNETIC FIELD MEASUREMENTS

Geophysics ◽  
1975 ◽  
Vol 40 (2) ◽  
pp. 269-284 ◽  
Author(s):  
J. E. Zimmerman ◽  
W. H. Campbell
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Quantum Interference ◽  
Field Tests ◽  
Field Measurements ◽  
Fluxgate Magnetometer ◽  
Superconducting Quantum Interference Device ◽  
Superconducting Quantum Interference ◽  
Field Fluctuations ◽  
Geomagnetic Measurements

A type of cryogenic SQUID (superconducting quantum interference device) magnetometer was designed for geomagnetic measurements. Field tests of the instrument including comparisons to observatory variometers, a rubidium magnetometer, an induction loop, and a fluxgate magnetometer showed the new cryogenic systems to be reliable, accurate, portable, and simple to operate. Directional measurements of natural magnetic field fluctuations as small as 0.0001 gamma with periods from 0.5 sec to several hours were demonstrated.

scholarly journals Error estimate for fluxgate magnetometer in-flight calibration on a spinning spacecraft

2021 ◽  
Vol 10 (1) ◽  
pp. 13-24
Author(s):  
Yasuhito Narita ◽  
Ferdinand Plaschke ◽  
Werner Magnes ◽  
David Fischer ◽  
Daniel Schmid
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Experimental Studies ◽  
Field Measurements ◽  
Fluxgate Magnetometer ◽  
Uncertainty Sources ◽  
Field Environment ◽  
Magnetic Field Measurements ◽  
Error Formulas ◽  
The Magnetic Field

Abstract. Fluxgate magnetometers are widely used for in situ magnetic field measurements in the context of geophysical and solar system studies. Like in most experimental studies, magnetic field measurements using the fluxgate magnetometers are constrained by the associated uncertainties. To evaluate the performance of magnetometers, the measurement uncertainties of calibrated magnetic field data are quantitatively studied for a spinning spacecraft. The uncertainties are derived analytically by perturbing the calibration parameters and are simplified into the first-order expression including the offset errors and the coupling of calibration parameter errors with the ambient magnetic field. The error study shows how the uncertainty sources combine through the calibration process. The final error depends on (1) the magnitude of the magnetic field with respect to the offset error and (2) the angle of the magnetic field to the spacecraft spin axis. The offset uncertainties are the major factor in a low-field environment, while the angle uncertainties (rotation angle in the spin plane, sensor non-orthogonality, and sensor misalignment to the spacecraft reference directions) become more important in a high-field environment in a proportional way to the magnetic field. The error formulas serve as a useful tool in designing high-precision magnetometers in future spacecraft missions as well as in data analysis methods in geophysical and solar system science.

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