Continuous Magnetic Field Research Articles

Design and development of thermo-electromagnetic system for spinodal decompositions of FeCrCo alloys

Permanent magnets are essential components of electromechanical devices. Majority of magnets are used in permanent magnet motors that have extensive application in relation to energy efficiency and sustainability like electric vehicles. This research is aimed for efficient manufacturing of FeCrCo permanent magnets. Electromagnets could be utilized for the generation of continuous magnetic field to use in number of manufacturing processes. A two-pole electromagnet, comprising of two solenoids each having 2200 turns of copper wire, was developed. The system was designed to produce magnetic field up to 10 kilo Gauss for spinodal decomposition of FeCrCo alloy samples under thermomagnetic treatment process. Being rare earth free alloys, FeCrCo magnet is gaining research focus as an alternative magnetic alloy for advanced applications. The electromagnetic system design was refined and confirmed by using the Finite Element Method. The experimental values, of magnetic field generated by the two-pole electromagnet setup, were well close to the simulation results. The magnetizing setup was utilized to treat the FeCrCo magnetic alloy samples simultaneously at high temperature (700 °C) and magnetic field (7 kilo Gauss). This thermo-magnetic setup helped to improve the metallurgical structures of FeCrCo to grow and develop more efficiently. Treated samples of FeCrCo alloy demonstrated enhanced magnetic properties due to effective spinodal decomposition. The improvement in magnetic properties was attributed to the elimination of retained alpha phase and formation of more alpha-1 phase.

3-D Current Density and Magnetic Field of 3-D MR Scanner Gradient Coil

The topic of this paper is to describe the 3-D current density in the windings of a 3-D coil, which fills the volume between two coaxial cylinders at a precisely defined distance from each other, and which serves to generate a magnetic field gradient in the center of the cylinder axis. The 3-D current density is considered an unknown input quantity, which is calculated from the known gradient magnetic field output. It is an inverse problem in mathematics, where the direct problems are the calculation of unknown output quantities based on known input quantities. Fourier series expansion methods in the context of cylindrical coordinates were used to describe the 3-D current density. In that case, Bessel functions are used as development components. The current densities, at each point in space, were lined up to represent current lines. Each power line is associated with a coil winding through which a current of a certain strength flows. After that, the principle of discretization of coil windings was applied. Each winding is divided into a large number of elementary segments that were considered as current elements, which create, based on Bio-Savar's law, an elementary magnetic field. In this way, the total, continuous magnetic field is broken into many elementary components, which come from different current elements. An important result of this process is that each current element can be controlled independently by a current source. This means that the output magnetic field of the gradient can be controlled by current sources, which are the input sizes, and this is what is at the core of the topic of this paper.

Anilato-Based Coordination Polymers with Slow Relaxation of the Magnetization: Role of the Synthetic Method and Anilato Ligand.

We have prepared and characterized three coordination polymers formulated as [Dy2(C6O4Cl2)3(fma)6] ⋅ 4.5fma (1) and [Dy2(C6O4X2)3(fma)6] ⋅ 4fma ⋅ 2H2O with X=Br (2) and Cl (3), where fma=formamide and C6O4X2 2-=3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone dianion with X=Cl (chloranilato) and Br (bromanilato). Compounds 1 and 3 are solvates obtained with slow and fast precipitation methods, respectively. Compounds 2 and 3 are isostructural and only differ in the X group of the anilato ligand. The three compounds present (6,3)-gon two-dimensional hexagonal honey-comb structures. Magnetic measurements indicate that the three compounds show slow relaxation of the magnetization at low temperatures when a continuous magnetic field is applied, although with different relaxation times and energy barriers depending on X and the crystallisation molecules. Compounds 1-3 represent the first examples of anilato-based lattices with formamide and field-induced slow relaxation of the magnetization.

Magnetic field-enhanced oxygen reduction reaction for electrochemical hydrogen peroxide production with different cerium oxide nanostructures

We investigated cerium oxide nanoparticles of various morphologies (nanosheets, nanocubes, and nanoparticles) supported on carbon Vulcan XC-72 for the two-electron oxygen reduction reaction (ORR). A continuous magnetic field (2000 Oe) was used for the first time in the literature. The best results were for 5 % (w/w) CeO2 for all three different morphologies, more than doubling the ring current, enhancing the hydrogen peroxide selectivity from 51 % (Vulcan XC-72) to 84–89 %, and modifying the onset potential to lesser negative values. The presence of the magnetic field led to even higher ring currents with 5 % (w/w) CeO2, H2O2 selectivity from 54 % (Vulcan XC-72) to 88–96 % and changing even more the onset potential. Those results were correlated with the Zeeman effect, the Lorentz force, generating magnetohydrodynamic effects, the Kelvin force, and the formation of Bound Magnetic Polarons. This pioneering research introduces an innovative approach, highlighting the potential of an external continuous magnetic field.

A Two-Temperature Fractional DPL Thermoelasticity Model with an Exponential Rabotnov Kernel for a Flexible Cylinder with Changeable Properties

This article presents a new thermoelastic model that incorporates fractional-order derivatives of two-phase heat transfer as well as a two-temperature concept. The objective of this model is to improve comprehension and forecasting of heat transport processes in two-phase-lag systems by employing fractional calculus. This model suggests a new generalized fractional derivative that can make different kinds of singular and non-singular fractional derivatives, depending on the kernels that are used. The non-singular kernels of the normalized sinc function and the Rabotnov fractional–exponential function are used to create the two new fractional derivatives. The thermoelastic responses of a solid cylinder with a restricted surface and exposed to a moving heat flux were examined in order to assess the correctness of the suggested model. It was considered that the cylinder’s thermal characteristics are dependent on the linear temperature change and that it is submerged in a continuous magnetic field. To solve the set of equations controlling the suggested issue, Laplace transforms were used. In addition to the reliance of thermal characteristics on temperature change, the influence of derivatives and fractional order was also studied by providing numerical values for the temperature, displacement, and stress components. This study found that the speed of the heat source and variable properties significantly impact the behavior of the variables under investigation. Meanwhile, the fractional parameter has a slight effect on non-dimensional temperature changes but plays a crucial role in altering the peak value of non-dimensional displacement and pressure.

Magnetic field control device for transplantation of corneal endothelial tissue with magnetic filaments.

The corneal endothelial transplantation involves the transfer and attachment of a single-layered corneal endothelial tissue to the narrow space between the cornea and iris. Given the high risk of damage to the endothelial tissue and surrounding corneal tissues when using sharp instruments inserted externally to apply force during the process, the development of a device capable of transferring corneal endothelial tissue using a magnetic field became necessary. This study aims to develop a magnetic control device for transferring corneal endothelial tissue with attached magnetic particles to the transplant site, validate its appropriate transfer capabilities, and assess its applicability to corneal endothelial transplantation. For this purpose, a magnetic field-generating manipulation device equipped with four electromagnets controlled by a joystick and microcomputer was developed. Through simulated experiments, the strength of the magnetic field and the attraction force on the tissue were predicted, and the actual magnetic field strength was measured for validation. To measure the magnetic transfer force, experiments were conducted by towing corneal endothelial tissue fixed with 6mg, 12mg, and 18mg plastic weights. Subsequently, the tissue's transfer speed was measured after applying continuous and pulsed magnetic fields. The results confirmed the feasibility of tissue transfer using the magnetic control device, and it was observed that pulsed magnetic fields led to faster transfer speeds and easier control compared to continuous magnetic fields. Exploratory animal experiments using rabbits were conducted to simulate real surgical conditions, confirming the feasibility of corneal endothelial tissue transfer and attachment.

Design and Development of Electromagnet Power Supply for Burst Mode Repetitive High Power Microwave Sources

Single frequency High-power microwave sources like Backward Wave Oscillator, Relativistic Magnetron etc., require a high magnetic field of about 1T to 4T for efficient operation. Single-shot HPM systems usually consist of pulsed magnetic systems. However, for repetitive HPM generation, a continuous magnetic field is required. To obtain a continuous high magnetic field in the required volume usually three solutions are worldwide preferred i.e., permanent magnet, DC electromagnet with cooling arrangements and superconductor-based magnetic coil. All these three systems are bulky, expensive and technologically demanding. In this paper, a novel power supply has been suggested that discharges a charged capacitor through a magnetic coil keeping the discharging current constant for a small period like hundreds of milliseconds to a second. An IGBT switch is used to discharge the capacitor1. The duty cycle of the IGBT switch is controlled using a current feedback signal from the hall sensor, thus keeping the current steady at a preset reference value. An experimental setup has been developed using a 300mF capacitor. A constant current up to 500A is achieved for 200mS. This system is scalable. For a longer duration of operation, more capacitor modules need to be added. Details of design, development and experimental results are presented in this paper.

Nonlinear Kinetic Inductance Sensor

The concept of nonlinear kinetic inductance sensor (NKIS) of electromagnetic radiation is proposed. The idea is based on divergency of kinetic inductanceLk∼dq/dI(ℏqis a momentum of superconducting electrons,Iis a supercurrent) of hybrid superconductor/normal metal (SN) bridge at currentI*Idep(Idepis a depairing current of the hybrid) and temperatureT* much smaller than critical temperatureTc. It makes possible to have large change of phase differenceδϕalong SN bridge in current biased regime atI≃I*even for small electron temperature increase. Appearance ofδϕis accompanied by the change of the current and magnetic flux through the coupled superconducting ring which could be measured with help of superconducting quantum interference device (SQUID). In some respect proposed sensor may be considered as a superconducting counterpart of transition edge sensor (TES) those work is based on large derivativedR/dT(Ris a resistance) nearTc. Because atI≃I*SN bridge is in gapless regime there is no low boundary for frequency of detected electromagnetic radiation. Our calculations show that such a sensor can operate in single photon regime and detect single photons with frequencyν≳10 GHz. We argue that the nontrivial dependenceI(q)of SN bridge could be also used in detectors of continuous electromagnetic radiation, current and magnetic field sensors.

Enhanced magnetoelectric coupling effect in Mg-doped Y-type hexaferrite BaSrCo2-xMgxFe11.1Al0.9O22 ceramics

The influences of Mg doping on the magnetic order structure and magnetoelectric (ME) effect were investigated in Y-type hexaferrite BaSrCo2-xMgxFe11.1Al0.9O22 (x = 0.00, 0.25, 0.50, 0.75, 1.00) ceramics. The results revealed that the Mg doping could increase the magnetic phase transition temperature. The optimal magnetic-driven electric polarization could be obtained at x = 0.25 ceramic, exhibiting a maximum electric polarization of 16.22 μC/m2 and a ME coefficient of 203 ps/m at 100 K. The stability of reversible electric polarization was demonstrated via the measurement of continuous magnetic field cycles. Moreover, the ME phase diagram was established by measuring the magnetic dielectric properties. Finally, a possible Mg-tune magnetic structure was proposed to explain the enhanced ME effect.

Experimental investigation on magnetic field strength providing thrust saturation in a magnetic nozzle radiofrequency plasma thruster

Magnetic field strength applied to a magnetic nozzle radiofrequency (rf) plasma thruster having a 10.5 cm diameter source tube is increased up to about 3 kG by pulsing the solenoid current. A target plate is installed at 30 cm downstream of the source and an impulse bit exerted to the target is measured to assess the thrust, where the thrust balance measurement was impossible due to the interaction between the pulsed magnetic fields and the eddy currents on surroundings. Since the diameter of the plasma plume at the target location is larger than the target diameter, a comparison between the thrust balance and target measurements under continuous magnetic field and rf power is performed prior to the pulsed magnetic field experiments, showing that about 65 percent of the plasma momentum is exerted to the target plate. Saturation of the impulse bit, being equivalent to the force multiplied by the rf pulse width, is clearly observed when increasing the magnetic field strength. The magnetic field providing the force saturation is found to be changed by the source diameter, which is qualitatively explained by considering a change in the plasma loss to the source wall in a thruster model containing the particle balance, power balance, and one-dimensional magnetic nozzle models. It is suggested that the magnetic field strength required for optimizing the force, i.e. the thrust, can be reduced when enlarging the source tube diameter.

Identification of Penetration and Disturbance Dynamo Electric Fields and Their Effects on the Generation of Equatorial Plasma Bubbles

AbstractA very challenging task in ionospheric studies is to determine the separate contributions of penetration and disturbance dynamo processes in the generation of equatorial plasma drift during magnetic storms. In this study, we analyze the ion drift measured by the Communications/Navigation Outage Forecasting System satellite during the magnetic storm on 15–16 July 2012. A unique feature of this storm is the exceptionally long period of continuous southward interplanetary magnetic field (IMF) for 32 hr. The storm‐induced net change of the meridional/vertical ion drift, the difference drift between the storm time and the quiet time, is derived during the storm main phase and the first 20 hr of the recovery phase with southward IMF. The difference drift during the recovery phase cannot be explained by the disturbance dynamo effect alone. A new method is used to separate the drifts caused by the penetration and disturbance dynamo processes. The penetration drift is represented by an empirical pattern of penetration electric field and depends on the IMF magnitude, and the disturbance dynamo drift is obtained by subtracting the penetration drift from the measured difference drift. The derived disturbance dynamo drift is in good agreement with previous statistical pattern. This is the first effort to identify the separate contributions of the penetration and disturbance dynamo processes to the total drift from observed data. The results have important implications in identifying storm‐time penetration and disturbance dynamo electric fields and their effects on the generation and evolution of plasma bubbles.

Multi‐Site Transfer Function Approach for Real‐Time Modeling of the Ground Electric Field Induced by Laterally‐Nonuniform Ionospheric Source

AbstractWe propose a novel approach to model the ground electric field (GEF) induced by laterally‐nonuniform ionospheric sources in real time. The approach exploits the multi‐site transfer function concept, continuous magnetic field measurements at multiple sites in the region of interest, and spatial modes describing the ionospheric source. We compared the modeled GEFs with those measured at two locations in Fennoscandia and observed good agreement between modeled and measured GEF. Besides, we compared GEF‐based geomagnetically induced current (GIC) with that measured at the Mäntsälä natural gas pipeline recording point and again observed remarkable agreement between modeled and measured GIC.

An Improved In-Flight Calibration Scheme for CSES Magnetic Field Data

The CSES high precision magnetometer (HPM), consisting of two fluxgate magnetometers (FGM) and one coupled dark state magnetometer (CDSM), has worked successfully for more than 5 years providing continuous magnetic field measurements since the launch of the CSES in February 2018. After rechecking almost every year’s data, it has become possible to make an improvement to the in-flight intrinsic calibration (to estimate offsets, scale values and non-orthogonality) and alignment (to estimate three Euler angles for the rotation between the orthogonalized sensor coordinates and the coordinate system of the star tracker) of the FGM. The following efforts have been made to achieve this goal: For the sensor calibration, FGM sensor temperature corrections on offsets and scale values have been taken into account to remove seasonal effects. Based on these results, Euler angles have been estimated along with global geomagnetic field modeling to improve the alignment of the FGM sensor. With this, a latitudinal effect in the east component of the originally calibrated data could be reduced. Furthermore, it has become possible to prolong the updating period of all calibration parameters from daily to 10 days, without the separation of dayside and nightside data. The new algorithms optimize routine HPM data processing efficiency and data quality.

Influence of field-induced anisotropy on magnetic properties and domain structure of Fe-based nanocrystalline alloy via a new continuous magnetic field annealing furnace

Influence of field-induced anisotropy on magnetic properties and domain structure of Fe-based nanocrystalline alloy via a new continuous magnetic field annealing furnace

Recording the Magnetic Field Produced by an Undersea Energy Generating Device: A Low-Cost Alternative

This work describes the characteristics of a device capable of detecting the magnetic field generated by a submerged electrical conductor. This low-cost apparatus is based on the open-source Arduino platform and offers the possibility of monitoring magnetic fields generated by undersea cables. Measuring magnetic fields generated by undersea cables facilitates the development of technologies that will harness marine energy potential. The research is based on published parameters of magnetic field values generated by existing submarine cables. A coil was built to simulate an approximate magnetic field at 10 mT. The magnetic field generated by the coil was used as a reference standard. The device developed has a measurement probe built with an array of SS49E Hall effect sensors placed in a straight line and separated 5 cm from each other. A DS18B20 temperature sensor was added to make the necessary corrections and cancel the influence of temperature during the measurements. A microSD card module was attached to store continuous magnetic field measurements. The device was adjusted under strict laboratory conditions. The functionality of the device developed was confirmed by two samplings in the sea. In these samples, the magnetic field generated by the coil was measured in the entire water column from a depth of 3 m to 150 m. Results indicate that the prototype can successfully perform the necessary functions to quantify the underwater magnetic field accurately with about 10 µT accuracy.

Intrinsic evolution of the decoupling and coupling of the plasma density and temperature in a cylindrical laboratory plasma device

An intrinsic evolution in the decoupling–coupling–decoupling (DCD) of the electron density and temperature responding to the magnetic field change is observed in a cylindrical laboratory plasma device. Experimental results show that the density and the temperature decouple in the low magnetic field, couple with higher magnetic field, and decouple again with a continuous magnetic field increase. An element physical picture of the DCD regime is unraveled based on the analyses of gradient lengths, the turbulence propagation directions, the turbulence spatial scales, and the relationship between the normalized collision rates and the poloidal mode numbers.

Magnetic photo-thermal evaporator with joule-assisted heating for stable vapour generation

Solar energy has the potential to be applied in the production of vapour that relies on high-temperature liquids in conventional ways because it is one of the reproducible energy sources. In this work, a magnetic photo-thermal evaporator (MPE) based on nickel foam coated with reduced-graphene-oxide is used to produce vapour. The increase of thermal conversion efficiency can be implemented by a solar absorbed structure that promotes the vaporization of generated water. MPE has its optimal energy conversion efficiency of 98 %. Due to the coupling joule heat and solar thermal processes, the efficient and stable interfacial evaporated performance could be controlled, which is to optimize the multi-process coupling and multi-energy complementary process and promote the actual applications of MPE. Under the solar power of 1000 W·m−2, the evaporation rates obtained were 1.75 kg·m−2·h−1 and 1.81 kg·m−2·h−1 for the coupled continuous and segmented magnetic fields for the 90 s, which are much higher than the theoretical evaporation rate limit for two-dimensional interfacial photo-thermal evaporator. In case of extreme water shortage, the magnetic field can be used to assist in the rapid extraction of fresh water. The advantages of rapid fabrication and lower cost of the MPE have made the developments of solar evaporator applications possible such as desalination and wastewater treatment.

A comparative study of a thermoelastic problem for an infinite rigid cylinder with thermal properties using a new heat conduction model including fractional operators without non-singular kernels

In this research, two alternative approaches to fractional derivatives, namely Caputo–Fabrizio (CF) and Atangana–Baleanu (AB) fractional operators, are used to propose a generalized model of thermoelastic heat transfer of a rigid cylinder with thermal characteristics. The proposed model can be constructed by combining the DPL model with phase delays and the two temperature theories. It will be taken into account that the solid cylinder has variable physical properties. It was also assumed that the surface of the cylinder is penetrated by a continuous magnetic field and is regularly exposed to thermal loading from a continuous heat source. The numerical solutions of the studied physical fields in the AB and CF fractional derivative cases were derived using the Laplace transform method and are compared visually and tabularly and discussed in detail.

Nonlocal magneto-thermoelastic infinite half-space due to a periodically varying heat flow under Caputo–Fabrizio fractional derivative heat equation

Abstract This article deals with a new modified heat conduction model with fractional order that includes the Caputo–Fabrizio differential operator (CF) and the thermal relaxation time. This new approach to the CF fractional derivative has attracted many researchers because it includes a nonsingular kernel. The nonlocal theory proposed by Eringen has also been applied to demonstrate the effect of scale-dependent thermoelastic materials. The problem of thermal isotropic semi-infinite space is addressed as an application of the presented model. The medium is exposed to regularly changing heat sources and is initially placed in a continuous external magnetic field. The system of governing equations was expressed in the field of the Laplace transform, and the problem in this field was solved by the state-space operation. The inverse of the transformed expressions of physical quantities is found numerically using Zakian’s algorithm. The effects of the nonlocal parameter, the fractal order parameter, and the magnetic field were graphically presented and analyzed in detail. Some of the previous investigations were extracted in some special cases.

43+T Grenoble hybrid magnet: Commissioning tests of the current leads and cryogenic satellite producing the pressurized superfluid He at 1.8 K

The Grenoble Hybrid magnet is a modular platform using resistive and superconducting technologies to produce various continuous high magnetic field and flux configurations for the scientific community. They range from 43 T in 34 mm diameter with 24 MW electrical power to 9 T in 800 mm diameter when the superconducting coil is used alone. Thanks to the ongoing upgrade of the electrical power installation of LNCMI-Grenoble up to 30 MW and possibly to 36 MW, the possibility to increase the total field up to 45-46 T in the near future is foresee and deeply studied. The key design parameters will be briefly recalled including the specifically developed Nb-Ti/Cu conductor, the large bore outsert superconducting coil, the magnet cryostat with its structure including the eddy-current shield, the cryogenic line for the interconnection with the cryogenic satellite and the fully dedicated 150 l/h He liquefaction plant. All components of the hybrid magnet platform have been built, tested and delivered to LNCMI-Grenoble, where integration and assembly are ongoing. The status of the project will be given with focus to the recent commissioning tests of the cryogenic satellite producing the pressurized superfluid He at 1.8 K as well as to the successful powering tests of the specially developed current leads at ultimate current and under fully degraded cooling conditions simulating the worst-case accidental scenario.