Induced Magnetic Field Research Articles

Improvement of superconducting, morphological, and flux pinning ability of YBa2Cu3O7-y matrix with oxygen and Mn2O3 impurity

Abstract In the current work, the influence of oxygen and Mn2O3 impurity levels intervals 0.00≤x≤0.30 on various key properties such as electrical resistivity, superconducting, flux pinning ability, stabilization of ceramic system, and morphological properties of YBa2Cu3O7-y (Y-123) superconductor were examined by electrical resistivity, critical current density, and scanning electron microscopy (SEM), electron dispersive X-ray (EDX) measurements. The EDX test results indicated that all the Y-123 ceramics produced possessed different composition distributions on the sample surface. SEM photomicrographs also confirmed the improvement in the appearance of surface morphology and crystallinity quality of the YBa2Cu3O7-y system. Moreover, the development in the interaction quality between grains, pinning ability and strength quality of 2D coupled vortices was obtained with the oxygen ambient and optimum manganese impurity addition highly dispersing throughout the intra grain and inter-grain boundary couplings due to the increase in the artificial flux pinning nucleation sites in the Y-123 system. Thus, the best sample with the highest Jc value of 98 A/cm2 showed the most resistance to the applied magnetic field and current. Similarly, the same sample exhibited the greatest superconductive offset (98.320 K) and onset (100.504 K) temperatures values based on the development of the Cu-O coordination and stability of the crystal structure. In conclusion, this comprehensive study based on the analysis of oxygen and Mn2O3 impurity addition mechanism through the YBa2Cu3O7-y ceramic matrix may open a new and applicable field for advanced engineering, heavy industry technology and large-scale applications.

Development of a Reliable Assay of Eco-friendly Fe3O4@Ag Nanocomposite-Based Giant Magnetoresistance Sensor

Abstract For the development of green magnetic-based immunoassay devices, the rapid and reliable assay method of eco-friendly magnetic labels with a lower energy requirement is vital. This work proposes a green-synthesized Fe3O4@Ag magnetic label assay system using GMR chips and a simple microcontroller-based data acquisition tool. Optical analysis shows the successful synthesis of Fe3O4@Ag with the assistance of Moringa oleifera (MO) extract as a reducing and stabilizing agent. Meanwhile, according to characterization, MO-assisted green-synthesized Fe3O4@Ag nanocomposites feature cubic inverse spinel structures and ferromagnetic characteristics that possess multi-domain structures. The sensor system generates an intense signal, varying from tens to hundreds of millivolts, allowing for its detection using a simple microcontroller system. The sensor exhibits a stable and reliable response to the increase in the concentration of Fe3O4@Ag nanocomposite, even though it is subjected to weak magnetic field induction. Furthermore, the introduction of Ag on the surface of Fe3O4 nanoparticles succeeded in optimizing the detection features, as evidenced by the lower limit of detection compared to detecting the bare Fe3O4. The GMR-based sensor, featuring a simple microcontroller structure and an eco-friendly Fe3O4@Ag nanocomposite as a magnetic label, exhibits significant potential as a rapid and reliable green biosensor that is power-efficient.

Performance evaluation of a racetrack high temperature superconductor winding in an HTS levitation platform

Abstract High temperature superconducting (HTS) is a key technology of next generation high-speed railway systems, which guarantees high current and highly efficient traction power supply. HTS devices can reduce system weight and thus improve loads of vehicles. On high-speed maglev trains, HTS windings wound by second-generation (2G) HTS tapes play an important role in suspension and traction. However, in complex ferromagnetic environments, the performances of windings are notably influenced by the varying magnetic fields. In this paper, a new maglev platform is designed and comprised of a winding of six racetrack HTS coils, an E shape iron core and a magnetic guide rail. The air core structure of the winding is modeled，tested and the electromagnetic characteristics are analyzed for three dimensional (3D) finite element analysis of the platform. An A formulation is used to calculate magnetic vectors A and infer magnetic flux densities and current densities for the structures. After the winding is installed on the iron core and the magnetic guide rail is suspended above the iron core, the air gap between the iron core and the rail is varied from 0 mm to 20 mm in models and experiments. The magnetic fields, critical currents and losses of the winding in cases of the air core and the iron core conditions are used for analysis. The comparison between the air core and the iron core conditions confirms the reliability of the proposed models. This study provides means for analysis of complex superconducting maglev systems.

Prevalence of Asymptomatic Changes in the Groin Region Among Adult Professional Soccer Players and Their Association With Limb Dominance

Objective: To investigate the prevalence of asymptomatic radiologic groin region findings in adult professional soccer players using magnetic resonance imaging (MRI) and examine the influence of age and limb dominance on their occurrences. Design: Cross-sectional trial. Setting: Soccer club medical service, private practice. Participants: Forty-seven male professional soccer players. Interventions: Players underwent a groin presigning MRI scan with a magnetic field induction of 1.5 Tesla. Image analysis of their pubic bones was performed according to The Copenhagen Standardized MRI protocol to assess the pubic symphysis and adductor regions of players. Main Outcome Measures: The prevalence of various changes in the symphysis, pubic bone, and adjacent areas. Results: Fifty images of pubic bones and adjacent regions (53.2%) highlighted 1 to 4 changes, while another 44 images (46.8%) demonstrated 5 or more changes. The most frequent changes observed in the pubic bone were joint surface irregularities (100%), symphyseal sclerosis (93.6%), pubic bone swelling (56.3%), parasymphyseal high-intensity line (55.3%), fatty infiltration in bone marrow (38.3%), and adductor tendinopathy (34%). When comparing the prevalence of different changes in the dominant and nondominant limbs, no statistically significant differences were found. Conclusions: In adult professional soccer players with no prior groin pain complaints in recent history (12 months), asymptomatic changes are extremely common in the pubic joint and adjacent areas, including those that are very likely to be considered the main cause of pain when investigated in soccer players with groin pain. None of these changes were associated with limb dominance.

Advanced Anti-icing and Deicing Strategies for Overhead Power Transmission Lines Based on Giant Magnetocaloric Effect of La0.7Ca0.254Sr0.046MnO3.

Perovskite manganates (AMnO3) exhibit diverse structural, thermal, electrical, and magnetic properties. Their strong magnetocaloric effect (MCE) near the Curie temperature (TC) makes them ideal for magnetic-thermal anti-icing and deicing in power transmission lines. Below TC, ferromagnetic AMnO3 produces heat through multiple mechanisms, with the changing magnetic field induced by the strong AC current, causing heat through magnetic hysteresis and eddy currents, alongside the direct MCE. Above TC, no heating is generated, as MCE is unfavorable, thus preventing additional energy loss at elevated temperatures. In this work, La0.7Ca0.254Sr0.046MnO3 with TC close to 0 °C were synthesized by solid-state reaction. It is found that particle size >10 μm is beneficial for a large MCE, based on the results of particle size dependence of MCE. The resulting maximum magnetic entropy change at 277 K is 7.69 J·kg-1·K-1, and an adiabatic temperature change of 3.87 K at 277 K is achieved under 5 T. The prototype cable is fabricated using a well-established wire drawing process. A climate-simulation chamber is employed for the anti-icing and deicing experiments. The prototype cables demonstrated a strong capability for deicing and anti-icing. This simple and cost-effective prototype cable shows significant potential for mitigating the icing problem of overhead high-voltage power transmission lines.

A surface-shunting method for the prevention of a fault-mode-induced quench in high-field no-insulation REBCO magnets

In this paper, we apply a surface-shunting method to prevent quenches in no-insulation (NI) REBCO magnets triggered by external failures of magnet current leads or power suppliers (i.e., fault mode). In a high-field magnet system, an NI coil may still be at risk during the mentioned quench events even if the whole magnet is well-designed, non-defective, and properly operated. The mechanism of this fault-mode quench initiation and propagation still remains unclear, complicating the development of reliable quench protection. Here, we present this mechanism to demonstrate a corresponding practical quench-preventive approach named surface shunting, which utilizes a low-temperature solder attached to the top and bottom of pancake coils. We validate the effectiveness of this approach by comparing the electromagnetic, thermal, and mechanical behaviors in the fault mode with and without the shunt. We conclude that the surface shunt suppresses the fault-mode quench initiation and propagation by redirecting the original turn-to-turn current and induced overcurrent out of the NI winding. We anticipate this work can provide a solution to improve the operational safety of high-field HTS NI magnets against quench and potential damage during fault modes.

MHD simulations of astrophysical and laboratory jets under different magnetic field configurations

This paper presents the results of MHD simulations of astrophysical and laboratory supersonic jets under a superposition of poloidal (Br, Bz) and toroidal (Bϕ) magnetic fields. It is shown that the escaping matter is quickly collimated by the magnetic field. A shock wave of an elongated shape is formed, which moves from the target to the boundary of the chamber, leaving behind a stable flow. A periodic shock wave structure is observed inside the main conical expanding shock wave. It is shown that the toroidal component of the magnetic field remains in the region throughout the entire calculation and plays a role in the collimation of the flow. The poloidal magnetic field decreases in the region of the jet cone, but remains in the simulation region throughout the calculation and also participates in flow collimation. Thus, both components Bz and Bϕ take part in the collimation of the flow by the magnetic field. The width of the jet and the opening angle of the cone Ɵ depend on the magnitude of the magnetic field induction. As the field increases, the jet becomes narrower and the cone angle decreases. Initially, we do not specify the rotation of the jet Ω. However, due to the presence of the Bϕ field, the substance acquires angular velocity and twists along the z axis. The simulation results are in agreement with laboratory jets arising in the experiment at the Neodymium laser installation, and with the previously obtained results of MHD modeling of jet formation separately, in poloidal or toroidal magnetic field.

Magnetic dipole contribution to the γ spectrum from d−t collisions

One in about a few 105 sub-Coulomb d−t collisions is accompanied by the emission of a γ photon. The γ spectrum from these collisions is dominated by a 16.7 MeV peak, corresponding to the population of the p-wave 3/2− α−n ground-state resonance in the E1 transition from an intermediate d-wave α−n state, corresponding to the He5 excited state around 16.7 MeV. The strength of this spectrum at the large γ-energy endpoint decreases fast both due to kinematic factors and due to centrifugal repulsion between neutron and α particle at near-zero relative energies. However, no centrifugal repulsion would occur if s-wave α−n states were populated in a magnetic dipole transition. Therefore, one can expect that close to the γ-spectrum endpoint around 17.5 MeV the M1 transition could dominate, leading to additional counts in experimental spectra which could be easily misinterpreted as a background. This work presents calculations of the M1 contribution to the d+t→α+n+γ cross section caused both by convection and magnetization currents. While the first contribution was found to be negligible, the one from magnetization depends strongly on the choice of the model for the d−t channel scattering wave function. Using d−t interaction models from the literature, represented either by a gaussian of by a square well, resulted in unrealistically strong M1 contribution. Withoptical folding potential constructed in the present work, correctly representing the sizes of deuteron and triton, the M1 contribution near the endpoint is reduced to about 2% of the 16.7-MeV E1 peak. Arguments in favor of more detailed calculations, that could potentially change this number, are put forward. Published by the American Physical Society 2024

Effect of external magnetic field on the fretting wear mechanism of the ferromagnetic materials

With the widespread implementation of maglev technology in fields such as rail transit and military, it is imperative to investigate the effects of magnetic fields on fretting damage in metallic materials. This study conducted multi-parameter fretting wear tests on typical ferromagnetic counterparts in the presence of an external permanent magnetic field. Subsequently, the wear behavior and damage mechanism of the fretting interface were elucidated through multi-scale characterization analysis. The results indicated that the operation state of the fretting interface was shifted towards the partial slip regime under the magnetic field. Meanwhile, the external magnetic field transformed the dominant wear mechanism from abrasive wear to adhesive wear. The influence of the external magnetic field on fretting wear has been demonstrated to manifest in dual aspects: Firstly, the Hertzian contact stress at the interface is enhanced by the magnetic field induction force, resulting in a remarkable reduction of about 79.83 % in accumulated dissipation energy; Secondly, the effectiveness of debris being expelled from the worn interface decreased, and the wear progression was further impeded by the accumulated debris, so that the abrasion loss is significantly reduced by about 60.66 %. These findings provide valuable theoretical data and practical reference for the protection of fretting damage in ferromagnetic materials under the action of a magnetic field.

Regulating mechanisms of external axial magnetic field on flow and heat transfer behavior for process optimization in plasma beam polishing

Plasma beam polishing has emerged as an innovative alternative to conventional metal finishing techniques. However, the precision machining ability of plasma arc encounters challenges due to the formation of surface undulations, while previous research has predominantly focused on parameter adjustments. In this paper, the feasibility of optimizing the plasma beam polishing process was validated through magnetic field regulation, as the surface topography and subsurface structure were obviously flattened. Given this, a micro plasma arc model under inhomogeneous axial magnetic field was established to explore the regulating mechanisms of the external axial magnetic field on the flow and heat transfer behavior of the plasma arc. Through this model, the plasma characteristics (magnetic induction intensity, electric potential, arc current, Lorentz force, plasma velocity and electron temperature) were comprehensively discussed. The results indicate that the external shape of the plasma arc is determined by the self-induced magnetic field, while the externally applied axial magnetic field significantly influences the internal flow of the plasma arc. The axial and radial magnetic fields generated by the excitation coil can induce circumferential rotation by dragging the plasma arc with Lorentz force, creating a more suitable energy beam for the polishing process. To verify the model, the arc temperature was measured using spectroscopic diagnostics, and the arc shape was captured using a high-speed camera, both of which were basically consistent with the simulation results.

The interplay between optoelectronic and magnetic properties in Co-doped Cu2ZnSnS4 for next-generation solar cell devices

Abstract A search for next-generation solar cell devices to massively actualize renewable energy is being exponentially conducted. It includes the development of Cu2ZnSnS4 (CZTS)-based solar cells, which are known as cost-effective and highly stable solar cell devices. In this present research, we develop a CZTS solar cell by adding a magnetic degree of freedom using cobalt (Co) doping. We find that the Co doping can induce modulation of the crystalline structure and bandgap of CZTS, which further influences its photovoltaic performance. The increase in the grain size of the CZTS with the addition of Co doping could further induce the reduction of detrimental grain boundaries, which benefits the photovoltaic performance of CZTS-based solar cells. Co doping also generates magnetic behavior in CZTS, which supports its magnetically controlled optoelectronic properties and thus, in turn, enhances the photovoltaic performance. We believe that this study could open up opportunities to obtain next-generation solar cell devices with excellent performances by using magnetic-field induction.

Acene-Integrated Buckybowls with Near-Infrared II Absorption and over 90% Photothermal Conversion Efficiency.

Tetracene and pentacene are large, promising building blocks for construction of complex molecular nanocarbons due to their extraordinary photophysical and electronic properties. Herein, two acene-integrated buckybowls, composed of two rows of tetracenes and pentacenes fused through s-indacene unit at the zigzag edges, have been synthesized and characterized. Compared to parent tetracene and pentacene, the buckybowls are extremely stable and show much smaller electrochemical bandgaps. Kinetic studies gave the bowl-to-bowl inversion barriers of 11.7 and 13.3 kcal mol-1. Subsequent investigations on magnetic ring currents revealed two local diatropic currents at two rows of acenes and one paratropic current at the s-indacene unit, respectively. Notably, both buckybowls show a broad absorption that reaches into near-infrared II region, and a high photothermal conversion efficiency (> 90%) was achieved when exposed to near-infrared 1064 nm laser photo-irradiation. This study highlights the unusual nature of merging the intrinsic properties of acenes with the inherent properties of buckybowls and showcases a potential avenue for acene utilization for the design of novel complex nanocarbons with a broad range of applications.

Acene‐Integrated Buckybowls with Near‐Infrared II Absorption and over 90% Photothermal Conversion Efficiency

Tetracene and pentacene are large, promising building blocks for construction of complex molecular nanocarbons due to their extraordinary photophysical and electronic properties. Herein, two acene‐integrated buckybowls, composed of two rows of tetracenes and pentacenes fused through s‐indacene unit at the zigzag edges, have been synthesized and characterized. Compared to parent tetracene and pentacene, the buckybowls are extremely stable and show much smaller electrochemical band gaps. Kinetic studies gave the bowl‐to‐bowl inversion barriers of 11.7 and 13.3 kcal mol‐1. Subsequent investigations on magnetic ring currents revealed two local diatropic currents at two rows of acenes and one paratropic current at the s‐indacene unit, respectively. Notably, both buckybowls show a broad absorption that reaches into near‐infrared II region, and a high photothermal conversion efficiency (> 90%) was achieved when exposed to near‐infrared 1064 nm laser photo‐irradiation. This study highlights the unusual nature of merging the intrinsic properties of acenes with the inherent properties of buckybowls and showcases a potential avenue for acene utilization for the design of novel complex nanocarbons with a broad range of applications.

Influence of γ-radiation on magnetoelectrical properties of Bi0.85Sb0.15 (0.001≤x≥0.05) solid solution

Abstract The influence of γ-quantum on the magnetoelectric properties of Bi0.85Sb0.15 <Pbx> (0.001≤x≥0.05) thermoelectrics doped with lead atoms at ~77÷300K and magnetic field induction up to 1.0 Tesla has been studied. It was found that at low doses of gamma irradiation of the Bi0.85Sb0.15 <Pb> solid solution, point defects are formed, which lead to an increase in the concentration of free electrons n, specific electrical conductivity σ and a decrease in the absolute value of the thermo EMF coefficients α and RH. As the dose of γ-quanta increases in the process of subsequent restructuring, point defects accumulate, i.e. accumulation of point defects, which leads to a decrease in the concentration of current carriers and a corresponding change in σ, α. and RH.

Improved prediction of critical currents for multi-pancake coil across variable temperature regions

With the increasing performance of the second-generation high-temperature superconducting (2G-HTS) tapes, the technology of all-REBa2Cu3O7-δ (REBCO, RE: rare earth) superconducting magnets has developed rapidly. However, the 2G-HTS magnet with hybrid cryocoolers constantly adjusts its operating temperature according to the actual demands, which involves the critical current when the magnet crosses variable temperature regions. In this paper, a modified ideal model based on the homogenization model is proposed, which can predict the critical current of 2G-HTS magnets more consistently. The in-field properties of REBCO tapes in variable temperature regions were tested by the physical property measurement system. Furthermore, the improved model was combined with the in-field properties of REBCO tapes to obtain the critical currents of a 2G-HTS multi-pancake (MP) coil at 20 K, 30 K, 65 K, and 77 K. The critical current of a multi-pancake coil at 77 K was experimentally verified. The modified ideal model uses the actual current density, which results are closer to the experimental results with an agreement of 97.3%. This new method proposed in this work is significant in quickly predicting critical currents for 2G-HTS magnets across variable temperature regions.

Total Magnetic Field Perturbations at Martian Low Altitudes (≤500 km): MAVEN Observations in 2014–2023

AbstractMagnetic perturbations in the Martian ionosphere are often considered as representing plasma irregularities, but thorough statistical comparisons between the two independent phenomena have been rarely conducted. In this study, we investigate the statistical relationship between total magnetic field perturbations and those of O2+ density as observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft at altitudes below 500 km in 2014–2023. From the 1 Hz time series of magnetic field strength, perturbation intensity is estimated by subtracting a signal smoothed with a Savitzky‐Golay filter (window size ∼36 km). Statistically, the magnetic perturbations are stronger on the dayside than at night, in the local summer hemisphere than in winter, and away from crustal magnetic anomalies than nearby. Also, day‐to‐day variability of the magnetic perturbations exhibits a weak but significant correlation with that of solar wind electron density. The statistical behavior of total magnetic field perturbations is not the same as that of O2+ density perturbations: that is, the former is not a perfect proxy for the latter. The seemingly counter‐intuitive discrepancy can be explained by effects of inhomogeneous background magnetic field strength (participating in total pressure balance across plasma perturbations) and localized ionospheric currents at altitudes unreachable by MAVEN.

ЗАСТОСУВАННЯ ФАЗНИХ СТРУМОВИХ КОНТУРІВ ДЛЯ МОДЕЛЮВАННЯ ГАРМОНІЙНОГО МАГНІТНОГО ПОЛЯ МАГНІТОЕЛЕКТРИЧНОГО ГЕНЕРАТОРА

The model of electromagnetic field of a magnetoelectric generator with a smooth cylindrical rotor and surface-mounted permanent magnets is investigated. Permanent magnets are interpreted using complex amplitudes of a system of current loops with harmonic currents. The aim of the study is to develop a mathematical model for calculating the harmonic magnetic field of a magnetoelectric generator with permanent magnets by replacing the permanent magnets with phase current loops with complex current amplitudes and to investigate its adequacy. Three variations of model representation of permanent magnets placed on the surface of the magnetic core are utilized. Depending on the model representation of permanent magnets, two dynamic generator models and two harmonic models have been developed. For each model, equations of the electromagnetic field are written. An example of a three-phase scheme of current loops of the rotor for modeling the electromagnetic field of the magnetoelectric generator with complex amplitudes of currents is presented. Comparison of the magnetic field induction, current, voltage, and electromagnetic torque is performed with three variations of magnet width relative to the pole pitch. References 14, figures 5, table 1.

Mechanical and high-temperature characterization of additively manufactured Ni-superalloys at SALSA neutron strain diffractometer

Neutron diffraction is a well-established method for the measurement and characterization of internal stresses in metallic and ceramic materials at room temperature. Some cases have been reported in the literature in which the method has been extended to higher temperatures. In this paper we report both novel setups for in-situ heat treatments and for in-situ mechanical testing at high temperature at SALSA in the Institut Laue-Langevin (ILL). Characterization of internal stresses in Ni-superalloys demonstrated the feasibility, stability and exploitation of results achieved by a tailored induction heating system. Different coils are adapted to accommodate several sample geometries for accurate focusing of the magnetic heating induction field on the sample, to achieve high heating rates up to 50 °C/s and therefore limiting the microstructural evolution impact during ramping-up to the target temperature. In return, this enhances the choice of reference d0, by either measurements at room temperature and extrapolated values to high temperature, or by direct measurements also at high temperature. A detailed strategy of d0 stress-free reference approaches for such in-situ experiments at high temperature is discussed.

Characteristics of Controlled Bridge Circuit and Its Application in Magnetic Field Induction Measurement

Characteristics of Controlled Bridge Circuit and Its Application in Magnetic Field Induction Measurement

A Wideband High Gain Differential Patch Antenna Featuring In-Phase Radiating Apertures.

Communication systems need antennas with wide bandwidths to provide large throughput, while imaging radars benefit from high gain for increased range and wide bandwidths for high-resolution imaging. This paper presents the design and evaluation of a wideband, high-gain antenna that achieves an average gain of 9.7 dBi over a bandwidth of 1.49 GHz to 3.92 GHz by using multiple in-phase radiating apertures. The antenna has a unique structure with a central rectangular short-circuited patch sandwiched between two back-to-back U-shaped radiating patches and two flanking H-shaped short-circuited patches. Each of the U-shaped patches employs a coplanar waveguide as feeding to achieve ultra-wideband impedance matching. Benefiting from design arrangement, in-phase electrical field distributions appear at the gaps between the patches that result in equivalent radiating magnetic currents in the same direction. Theory analysis shows that the close-spaced, same-direction magnetic currents created by the radiating apertures intensify the radiation and increase antenna gain within its impedance bandwidth. Simulated data show that the use of the coplanar waveguide feeding and short-circuited patches increase the bandwidth from 65 MHz to 2.43 GHz. Moreover, the short-circuited patches increase the gain by 3.45 dB at 2.4 GHz. Simulation and measurement results validate the design and show that the antenna features a maximum gain of 11.3 dBi and an average gain of 9.7 dBi in a fractional bandwidth of 89.8%. Because of the high gain values and the wide bandwidth, the antenna is particularly suited for long-range communication systems and high-resolution radar applications.