Two-Domain Model for Orthogonal Fluxgate

Butta, Mattia; Ripka, Pavel

doi:10.1109/tmag.2008.2003505

Cited by 10 publications

(7 citation statements)

References 16 publications

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“…When a magnetic field is applied in longitudinal direction (that is parallel to the cylinder), the magnetic domains rotating under the effect of , will be deflected, resulting in a net component of magnetic flux in longitudinal direction [1]. The variation of longitudinal flux is detected by a pickup coil wound around the core.…”

Section: Introductionmentioning

confidence: 99%

Bi-Metallic Magnetic Wire With Insulating Layer as Core for Orthogonal Fluxgate

et al. 2009

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In this paper, we examine the problems related to orthogonal fluxgates realized using magnetic microwires as core. Starting from a description of orthogonal fluxgates evolution, we give a theoretical analysis of the problems involving the full saturation of the wire, necessary condition to obtain proper working conditions. Bi-metallic wires (magnetic layer on copper wire, carrying the excitation current) have been proposed to achieve full saturation using lower current. In this paper, we present a further improvement: we realized microwires with insulation layer between the copper wire and the magnetic layer. The current flows only into the copper, regardless of the working frequency. Using insulation layer, we achieve 20 mA saturation current at 10 kHz, which is 3 times smaller than for similar wires without insulation layer.

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Section: Introductionmentioning

confidence: 99%

Bi-Metallic Magnetic Wire With Insulating Layer as Core for Orthogonal Fluxgate

et al. 2009

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“…The case without twisting has already been exposed in [16]. In that paper we explained the working mechanism for classical orthogonal fluxgate, with longitudinal anisotropy.…”

Section: Case Without Twistingmentioning

confidence: 97%

Model for coil-less fluxgate

Butta

Ripka

2009

Sensors and Actuators A: Physical

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“…At saturation (Fig. 5d), both ferromagnetic paths vanish, and inductances fall to air-core values (Butta and Ripka, 2008). Figure 5 is not useful for considering domains in polycrystalline permalloys.…”

Section: A Theory Of Noisementioning

confidence: 99%

“…Similar to the approach taken in Butta and Ripka (2008), the total energy is minimized when E d equals E s and when the dip angle is…”

Section: A Theory Of Noisementioning

confidence: 99%

The origin of noise and magnetic hysteresis in crystalline permalloy ring-core fluxgate sensors

Narod

2014

Geosci. Instrum. Method. Data Syst.

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Abstract. Developed in the 1960s for use in highperformance ring-core fluxgate sensors, 6-81.3 Mo permalloy remains the state of the art for permalloy-cored fluxgate magnetometers. The magnetic properties of 6-81.3, namely magnetocrystalline and magnetoelastic anisotropies and saturation induction, are all optimum in the Fe-Ni-Mo system.In such polycrystalline permalloy fluxgate sensors, a single phenomenon may cause both fluxgate noise and magnetic hysteresis; explain Barkhausen jumps, remanence and coercivity; and avoid domain denucleation. This phenomenon, domain wall reconnection, is presented as part of a theoretical model. In the unmagnetized state a coarse-grain highquality permalloy foil ideally forms stripe domains, which present at the free surface as parallel, uniformly spaced domain walls that cross the entire thickness of the foil. Leakage flux "in" and "out" of alternating domains is a requirement of the random orientation, grain by grain, of magnetic easy axes' angles with respect to the foil free surface. Its magnetostatic energy together with domain wall energy determines an energy budget to be minimized. Throughout the magnetization cycle the free-surface domain pattern remains essentially unchanged, due to the magnetostatic energy cost such a change would elicit. Thus domain walls are "pinned" to free surfaces.Driven to saturation, domain walls first bulge then reconnect via Barkhausen jumps to form a new domain configuration that I have called "channel domains", which are attached to free surfaces. The approach to saturation now continues as reversible channel domain compression. Driving the permalloy deeper into saturation compresses the channel domains to arbitrarily small thickness, but will not cause them to denucleate. Returning from saturation the channel domain structure will survive through zero H , thus explaining remanence. The Barkhausen jumps, being irreversible exothermic events, are sources of fluxgate noise powered by the energy available from domain wall reconnection.A simplified domain energy model can then provide a predictive relation between ring-core magnetic properties and fluxgate sensor noise power. Four properties are predicted to affect noise power, two of which are well known: saturation total magnetic flux density and magnetic anisotropy. The two additional properties are easy axes alignment and foil thickness. Flux density and magnetic anisotropy are primary magnetic properties determined by an alloy's chemistry and crystalline lattice properties. Easy axes alignment and foil thickness are secondary, geometrical properties related to an alloy's polycrystalline fabric and manufacture. Improvements to fluxgate noise performance can in principle be achieved by optimizing any of these four properties in such a way as to minimize magnetostatic energy.Fluxgate signal power is proportional to B − H loop curvature [d 2 B/dH 2 ]. The degree to which Barkhausen jumps coincide with loop curvature is a measure of noise that accompanies the fluxgate signal. B − H loops with si...

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Two-Domain Model for Orthogonal Fluxgate

Cited by 10 publications

References 16 publications

Bi-Metallic Magnetic Wire With Insulating Layer as Core for Orthogonal Fluxgate

Bi-Metallic Magnetic Wire With Insulating Layer as Core for Orthogonal Fluxgate

Model for coil-less fluxgate

The origin of noise and magnetic hysteresis in crystalline permalloy ring-core fluxgate sensors

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