Fluxgate Offset Study

Abstract

Offset and its long-term stability is a weak point of fluxgate sensors. Even the ultrastable sensors kept at no vibrations and stable temperature at magnetic observatories show offset drift. Such drift of fluxgate tri-axial sensor can be only partly corrected by scalar resonance magnetometer. Periodical calibration of absolute reading should be made using non-magnetic theodolite. In this paper we study the origin of fluxgate offset. We distinguish the real magnetic sensor offset from the offset contributions originating in false 2 nd harmonics signal which leaks to the sensor output from the distortion in the excitation signal, or which is borne as harmonic distortion when the signal processing electronics is subjected to large 1 st harmonic signal leaking from the excitation. We analyze the offset dependence on the angular position of the sensor core and its response to large field shocks. The experiments give an indication that only a part of the magnetic offset stems from a remanence of magnetically hard core regions. The residual part may be caused by magnetostrictive signal, belonging to false signal contributions, but not considered in previous studies.

High‐Fidelity Analysis of ULF Wave Mode Structure Following Interplanetary Shock Compression of the Dayside Magnetopause Using MMS Multi‐Point Observations

“…The total residual power in MMS magnetometers due to the limit of the detector capability was below $$2.5\times {10}^{-3}\,{\text{nT}}^{2}$$ during this event (Russell et al., 2016) which corresponds to residual power spectral density values in the range of $$(0.114,\,\,1.25)\sfrac{{\text{nT}}^{2}}{\text{Hz}}\,$$ for the resolved frequency band of $$(1.6,\,\,22.2)\,\text{mHz}$$. Therefore, the compressional power density threshold for the entire frequency band of interest (40 $$\sfrac{{\text{nT}}^{2}}{\text{Hz}}$$) is set to be larger than the residual power measured by MMS (related to the sensor offsets (Ripka et al., 2014)) by more than an order of magnitude. This threshold setting assures the reliability and coherence of the $$XPSD$$ in the analysis.…”

Tesseract – a high-stability, low-noise fluxgate sensor designed for constellation applications

“…However, it remains poorly understood and is not explicitly addressed by many authors in the literature. Fluxgate offsets are thought to originate primarily from the cores and driving electronics (Ripka et al, 2014), while changes in sensitivity and orthogonality are caused predominately by changes in the geometry of the sensor (Acuña et al, 1978;Miles et al, 2017). In this paper, we are concerned with the stability of the sensor.…”

“…Tesseract's Merritt coil feedback winding has been optimized to hold six racetrack cores within a highly homogeneous null field (de-viations from the average of less than 0.42 %), which allows for a reproducible magnetization of the ferromagnetic cores. This reproducibility is designed to improve the measurement stability (Ripka et al, 2014;Korepanov and Marusenkov, 2012) and linearity (Brauer et al, 1997) of the sensor.…”

Magnetostriction Offset of Fluxgate Sensors

“…Even though the A-type uncertainty of noise measurements is typically 10 to 20 %. By flipping the polarity of excitation and detector coils we are able to separate various parasitic offset components from the magnetic offset B 0mag [9]. Parasitic offset is caused by distortion in the excitation together with inductive and capacitive coupling (B 0ind+cap ) and also by the distortion in the processing electronics (B 0dis ).…”