The design of a ferrite-cored probe

May, Philip; Zhou, Erping; Morton, Danny

doi:10.1016/j.sna.2006.11.031

Cited by 19 publications

(3 citation statements)

References 1 publication

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“…Compared with a regular spiral coil, this coil has a small sensing area and spot size and nearly no limitation for the mounting space. Ferrite-cored probes can focus magnetic flux compared to air-cored probes [24]. Therefore, a highly focused magnetic field can be obtained by changing the core material and structure.…”

Section: Introductionmentioning

confidence: 99%

A magnetic head-based eddy current displacement sensing method

Chen,

Li,

Guo

et al. 2023

Phys. Scr.

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Eddy current displacement sensors are popular for sensing changes in displacement in industrial fields with many advantages. The eddy current induced by a conventional coil is distributed over a large range and the energy is not concentrated. The size of the minimum measured surface is 1.5 to 3 times the diameter of the coil. A magnetic head-based eddy current displacement sensor is proposed in this paper. Theoretical analysis confirms that the coil generates a highly concentrated magnetic field at the magnetic core gap. The simulations based on the finite element method are performed. The simulation results demonstrate that the proposed method can induce the eddy current field which has a small distribution range and high degree of concentration of energy on the surface of the specimen. Finally, experiments are conducted for different sized ring-shaped surfaces. The high similarity between the experimental results indicates that the magnetic head-based eddy current displacement sensor can induce a highly focused eddy current field with a distribution range of 3 mm. The sensitivity of the sensor is 5 V mm−1 and the spatial resolution of the sensor is 3 mm.

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Section: Introductionmentioning

confidence: 99%

A magnetic head-based eddy current displacement sensing method

Chen,

Li,

Guo

et al. 2023

Phys. Scr.

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“…A cylindrical ferrite core encircled by a coaxial rectangular cross-section coil is usually used to confine and enhance the magnetic field. The core can also be used to improve the signal-to-noise ratio, which is of particular benefit to measure magnetic substrate metals at relatively low frequencies [1]. The field of an air-cored probe above a single or layered conducting half-space has been studied in depth by using a number of approaches such as the analytical Dodd and Deeds model [2].…”

Section: Introductionmentioning

confidence: 99%

An analytical model of eddy current ferrite-core probes

Lü¹,

Bowler²

2012

AIP Conference Proceedings

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An analytical model of an axisymmetric eddy current probe with a cylindrical ferrite core above a layered conductive half-space is developed. Initially we consider the magnetic vector potential of a circular filament coaxial with a ferrite core over a layered conducting half-space. The principle of superposition is then used to derive close-form expressions for both the electromagnetic field and the impedance of a coil from the filament field. Rather than locating the probe in infinite space, it is confined coaxially within a circularly cylindrical boundary on which the vector potential field is zero. The radius of this artificial boundary is large in order to ensure that does not interfere substantially with the field near the probe. By using a truncated region in this way, the vector potential in the probe region can be expanded as a series rather than an integral form. Thus the solution of the problem amounts to finding the expansion coeefficients in the series. Published by the American Institute of Physics. Related ArticlesExperimental demonstration of the equivalence of inductive and strongly coupled magnetic resonance wireless power transfer Appl. Phys. Lett. 102, 053904 (2013) Complete analytical solution of electromagnetic field problem of high-speed spinning ball J. Appl. Phys. 112, 104901 (2012) The influence of demagnetizing effects on the performance of active magnetic regenerators J. Appl. Phys. 112, 094905 (2012) The analysis of single-electron orbits in a free electron laser based upon a rectangular hybrid wiggler Phys. Plasmas 19, 093114 (2012) A high-performance magnetic shield with large length-to-diameter ratio Rev. Sci. Instrum. 83, 065108 (2012) Additional information on AIP Conf. Proc. ABSTRACT. An analytical model of an axisymmetric eddy current probe with a cylindrical ferrite core above a layered conductive half-space is developed. Initially we consider the magnetic vector potential of a circular filament coaxial with a ferrite core over a layered conducting half-space. The principle of superposition is then used to derive close-form expressions for both the electromagnetic field and the impedance of a coil from the filament field. Rather than locating the probe in infinite space, it is confined coaxially within a circularly cylindrical boundary on which the vector potential field is zero. The radius of this artificial boundary is large in order to ensure that does not interfere substantially with the field near the probe. By using a truncated region in this way, the vector potential in the probe region can be expanded as a series rather than an integral form. Thus the solution of the problem amounts to finding the expansion coefficients in the series. The numerical predictions of probe impedance have been compared with experimental data showing good agreement.

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“…To date, many researchers continue to investigate and develop new EC probes to achieve a high SNR to predict the size of increasingly minor defects. A ferrite core was applied as the core material of the excitation coil to increase the magnetic field amplitude and thus enhance the defect detection ability owing to its high permeability [26][27][28][29][30][31] . To date, UEC probes have had a disadvantage in detecting small defects because there is a requirement for a large excitation current intensity and thus a large structure of the probe for a strong EC to be generated on the test piece surface to increase the detection sensitivity.…”

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confidence: 99%

A sophisticated design of copper core to converge rotating eddy current control for detecting cracks in conductive materials

Trung

Kasai

Sekino

et al. 2023

Sci Rep

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Eddy current (EC) testing has been selected as a standard candidate for detecting defects in conductive materials in the past few decades. Nevertheless, inventing EC probes capable of detecting minor defects has always been challenging for researchers due to the tradeoff between the probe dimensions and the strength of the EC generated on the surface of the test piece. Here, we use a copper core with a sophisticated design to converge the rotating EC at the tip of the copper core to detect small cracks in all directions in conductive materials. In this method, we can arbitrarily accommodate a large excitation coil so that a larger rotating uniform EC is generated in a small area of the test piece. Hence, the probe can detect cracks in all directions in conductive materials.

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The design of a ferrite-cored probe

Cited by 19 publications

References 1 publication

A magnetic head-based eddy current displacement sensing method

A magnetic head-based eddy current displacement sensing method

An analytical model of eddy current ferrite-core probes

A sophisticated design of copper core to converge rotating eddy current control for detecting cracks in conductive materials

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