Effect of Amorphous Wire Core Diameter on the Noise of an Orthogonal Fluxgate

In this paper, the performance of orthogonal fluxgate sensors with meander-shaped cores is studied in fundamental mode. The meander-shaped cores are made by micro-patterning technology based on a Co-based amorphous ribbon. The main advantage of this structure is that the linear operating range of the sensor can be adjusted simply by changing the number of strips, without affecting the excitation mechanism. Experiments show that a linear range of 560 μT is obtained by a meander-shaped core sensor with 12 strips. The changes in the number of strips can also increase sensitivity and reduce noise of the sensor. We can achieve a sensitivity of 600 V/T and a noise level of 0.64 nT/√Hz at 1 Hz for a meander-shaped core sensor with eight strips. Compared with the performance of the sensors built using a single strip core having the same equivalent cross-sectional area, the use of meander-shaped core can provide a higher sensitivity and linearity, and a lower noise level. We also compare the performance of an eight-strip meander-shaped core orthogonal fluxgate operated in the fundamental and second-harmonic modes. Similar sensitivity for the two modes can be obtained by adjusting the excitation current. In this case, we find that the noise of sensor operating in fundamental mode is about five times lower than that of the sensor operating in second-harmonic mode. This can be interpreted as the suppression of Barkhausen noise by unipolar bias in the fundamental mode.

Section: Resultsmentioning

confidence: 99%

Improved Performance of Fundamental Mode Orthogonal Fluxgate Using a Micro-Patterned Meander-Shaped Ribbon Core

Zhi

Zhang

Lei

2019

“…To date, most works are devoted to eliminating this kind of noise and much progress has been made. Researchers have applied various methods such as optimizing the geometry to reduce the demagnetization and using multiple wires and the Barkhausen noise has thus been reduced to a very low level [23], but the total noise is still in a high level and the origin of the remaining noise is unclear. In [20], Butta et al proposed that the remaining noise may come from the magnetostriction of the wire.…”

Section: Noisementioning

confidence: 99%

Recent Progress of Fluxgate Magnetic Sensors: Basic Research and Application

Wei

Liao

Zhang

et al. 2021

Fluxgate magnetic sensors are especially important in detecting weak magnetic fields. The mechanism of a fluxgate magnetic sensor is based on Faraday’s law of electromagnetic induction. The structure of a fluxgate magnetic sensor mainly consists of excitation windings, core and sensing windings, similar to the structure of a transformer. To date, they have been applied to many fields such as geophysics and astro-observations, wearable electronic devices and non-destructive testing. In this review, we report the recent progress in both the basic research and applications of fluxgate magnetic sensors, especially in the past two years. Regarding the basic research, we focus on the progress in lowering the noise, better calibration methods and increasing the sensitivity. Concerning applications, we introduce recent work about fluxgate magnetometers on spacecraft, unmanned aerial vehicles, wearable electronic devices and defect detection in coiled tubing. Based on the above work, we hope that we can have a clearer prospect about the future research direction of fluxgate magnetic sensor.

“…If the cooling process is fast enough, the wire is solidified in its amorphous form. This brings excellent magnetic properties, such as low coercivity (tens of A/m [ 2 , 3 ]) and vanishing magnetostriction (

) [ 4 , 5 ]. These characteristics make Cobalt-rich wires ideal for different magnetic sensors [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

An Improved Composition of CoFeSiB Alloy for Orthogonal Fluxgates

Butta

Janošek

Pařez

et al. 2022

Self Cite

Orthogonal fluxgates in fundamental mode based on (Co0.94Fe0.06)72.5Si12.5B15 cores have recorded very low noise in literature, especially if Joule annealing is performed on the core for a short period of time. However, for annealing time longer than 20–30 min, the noise of the sensor has a tendency to increase. In this work, we investigated this phenomenon, and we have found its origin in a monotonic increase of magnetostriction during the annealing process. We show that the wires with vanishing magnetostriction in their as-cast form exhibit positive magnetostriction after long-time annealing (more than 30 min), which increases the noise of the sensor. After researching the effect of the magnetostriction after annealing on the noise, we propose an alloy with a reduced amount of iron. Less iron leads to a larger as-cast negative magnetostriction, which becomes almost zero after long-time annealing (60 min), bringing further reduction of noise. We prove this effect on two wires from two different manufacturers, although with the same composition. The noise decrease with prolonged annealing is mainly observable in the low-frequency region: at 100 mHz, the noise of a single-wire sensor decreased from 20pT/Hz to 6pT/Hz when the annealing time was prolonged from 10 to 60 min.