•An optical fiber magnetic field sensor was constructed by incorporating magnetic fluid and a core–cladding–mode interferometer.•The sensing performances of the sensors are controllable by designing ...the parameters of the asymmetric-tapered structure.•The sensitivity of sensor with axial offset of 168μm and taper waist diameter is ∼162.06pm/mT ranging from 0 to 21.4mT.
We report an optical fiber magnetic field sensor by merging the advantages of magnetic fluid and a core–cladding–mode interferometer which is directly fabricated on a standard single-mode fiber by using an arc fusion splicing machine. The sensing performances of the sensors are controllable by designing the parameters of the asymmetric-tapered structure. Experimental results show that the sensor with axial offset of 168μm and taper waist diameter of 45μm not only has good optical properties but also a relatively high magnetic-field sensitivity of ∼162.06pm/mT ranging from 0 to 21.4mT. The proposed sensors would find potential applications in weak magnetic sensing fields.
In this study, non‑hydrogenated diamond like carbon (DLC) coatings were deposited by sputtering a graphite target in argon (Ar) by high power impulse magnetron sputtering (HiPIMS) using deep ...oscillation pulses. The effects of the magnetic field strength (B) tangential to surface of the target racetrack on the deposition parameters were studied. The structure, adhesion, and mechanical properties of DLC coatings deposited at different B were investigated by scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), scratch test, and nanoindentation. The tribological properties of the DLC coatings were evaluated using ball on disk wear test under dry and lubricated test conditions. It was found that the peak target current and substrate current density increased as B increased due to the enhanced electron confinement which results in an increased ionization efficiency. The enhanced ion bombardment was beneficial for improving the structure and properties of DLC coatings. As B increased, the DLC coatings exhibited more compact structure, smaller carbon mounds, and higher sp3 bond fractions. The improvement of the microstructure of the DLC coatings contributed to improved hardness and wear resistance of the coatings in both dry and lubricated test conditions. However, the deposition rate decreased at higher B owing to the high probability of back-attraction of carbon ions. The results suggested that controlling B in the range of 600 G to 700 G is important for achieving fully dense structure, high sp3 bond fractions, and high hardness for the DLC coatings deposited using HiPIMS. A further increase in B to 850 G showed no significant changes in the magnetic field induced effects on the structure and properties of the coatings.
•A stronger magnetic field increased peak target current and substrate current density in HiPIMS.•An ideal magnetic field for HiPIMS DLC coating depositions was between 600 G and 700 G.•Further increasing the magnetic field to 850 G showed limited benefits.•The deposition rate of HiPIMS decreased as the magnetic field strength increased.
The novel controllable behaviour of magnetorheological (MR) fluid is the backbone of magnetorheological fluid-based finishing processes. MR fluid-based finishing processes facilitate better control ...over finishing forces as the stiffness of MR finishing fluid used in these processes can be controlled in accordance with the applied magnetic field and MR finishing fluid composition. Therefore, a detailed experimental investigation was carried out to find the effect of MR finishing fluid constituents on its yield stress through the Taguchi Design of Experiments. Rheological data obtained from a magneto-rheometer (MCR-102) was characterised by using Bingham plastic, Herschel–Bulkley and Casson’s fluid constitutive modelling. The coefficient of regression (R2) values of Herschel–Bulkley model were found to be best suited for all compositions of MR finishing fluid. Analysis of variance (ANOVA) has been used to find the contribution of selected parameters for improving the response characteristics. The optimized fluid has been then used for the finishing of biocompatible stainless steel AISI 316L, and the finishing results show that the average surface roughness value decreases down to 58 nm.
In this article, we propose a magnetic field sensor based on a multimode-D-type-multimode (MMF-D-type-MMF) fiber structure employing surface plasmon resonance (SPR). The sensor's surface is coated ...with a layer composed of indium tin oxide (ITO), silver (Ag), and a 2-D material known as Bi2O2Se. Bi2O2Se exhibits varying magnetic permeability within a specific magnetic field strength range, a characteristic confirmed in practical tests. To enhance the sensor's sensitivity to magnetic fields, we implemented several optimization measures. These measures encompassed adjustments to: 1) the concentration of the magnetic fluid (MF); 2) the thickness of the Bi2O2Se layer; and 3) the selection of fiber type. We conducted simulations and experimental tests to refine these parameters. Consequently, the proposed D-type sensor demonstrates a sensitivity of 0.4325 nm/GS within the 40-150 GS magnetic field strength range, representing a significant 75.31% sensitivity improvement achieved through the aforementioned enhancement measures. When compared to other fiber-optic magnetic field sensors, our proposed sensor stands out for its exceptional sensitivity, straightforward design, robust repeatability, strong anti-interference capabilities, and high stability. As a result, it holds significant potential for a wide range of applications in aerospace, aviation, environmental monitoring, and related fields. The sensor has a high sensitivity in the range of 40-150 GS, which can monitor the magnetic field strength in life in real time and determine whether it meets the human body safety magnetic field standard.
Fluxgate Sensor with Bifactor Excitation Mode Bryakin, Ivan V; Bochkarev, Igor V; Khramshin, Vadim R ...
Sensors (Basel, Switzerland),
02/2023, Letnik:
23, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The paper considers non-destructive testing (NTDs) as a means to solve the flaw detection problems of magnetic products. It proposes a new probe-coil magnetic-field NDT, not requiring the ...pre-magnetization of the test object material, which is mandatory for all conventional magnetic flaw detection techniques. A new bifactor excitation of the fluxgate sensor's sensitive element, based on double μ-transformation through the simultaneous activation of magnetic-modulating and electromagnetic-acoustic effects, is theoretically justified. The physical processes underlying the proposed technique are considered in detail, and a scheme for its practical implementation is described. The authors provide a variant of the new fluxgate's original design, implementing the proposed excitation technique. The specifics of implementing the fluxgate operating modes are analyzed, testifying to the possibility of detecting a given class of flaws with the required coverage as well as ensuring the required diagnostic resolution during flaw detection, which, in fact, indicates a more reliable identification of both the flaw type and location. Herewith, the new fluxgate type features the advantages of improved functionality and lower cost due to its simple design. The paper also considers a method to experimentally study the capabilities of the proposed fluxgate sensor with a new bifactor excitation in detail. The results of the experimental study into its key specifications are provided, confirming its high resolution, narrower zone of uncertainty, and the possibility of detecting smaller flaws at greater depths compared to available analogs.
The origin of highly magnetized white dwarfs has remained a mystery since their initial discovery. Recent observations indicate that the formation of high-field magnetic white dwarfs is intimately ...related to strong binary interactions during post-main-sequence phases of stellar evolution. If a low-mass companion, such as a planet, brown dwarf, or low-mass star, is engulfed by a post-main-sequence giant, gravitational torques in the envelope of the giant lead to a reduction of the companion's orbit. Sufficiently low-mass companions in-spiral until they are shredded by the strong gravitational tides near the white dwarf core. Subsequent formation of a super-Eddington accretion disk from the disrupted companion inside a common envelope can dramatically amplify magnetic fields via a dynamo. Here, we show that these disk-generated fields are sufficiently strong to explain the observed range of magnetic field strengths for isolated, high-field magnetic white dwarfs. A higher-mass binary analogue may also contribute to the origin of magnetar fields.
Elementary chemistry distinguishes two kinds of strong bonds between atoms in molecules: the covalent bond, where bonding arises from valence electron pairs shared between neighboring atoms, and the ...ionic bond, where transfer of electrons from one atom to another leads to Coulombic attraction between the resulting ions. We present a third, distinct bonding mechanism: perpendicular paramagnetic bonding, generated by the stabilization of antibonding orbitals in their perpendicular orientation relative to an external magnetic field. In strong fields such as those present in the atmospheres of white dwarfs (on the order of 10 5 teslas) and other stellar objects, our calculations suggest that this mechanism underlies the strong bonding of H 2 in the $^ 3\sum \display _{u} ^{+} (1 \sigma _g 1 \sigma _{u} ^{*})$ triplet state and of He 2 in the $^ 1\sum \display _{g} ^{+} (1 \sigma _{g} ^{2} 1 \sigma _{u} ^{*2} )$ singlet state, as well as their preferred perpendicular orientation in the external field.
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