Large Magnetic Force Research Articles

Complete and robust magnetic field confinement by superconductors in fusion magnets

The fusion created by magnetically confined plasma is a promising clean and essentially unlimited future energy source. However, there are important problems hindering controlled fusion like the imperfect magnetic confinement and the associated plasma instabilities. We theoretically demonstrate how to create a fully confined magnetic field with the precise three-dimensional shape required by fusion theory, using a bulk superconducting toroid with a toroidal cavity. The vacuum field in the cavity consists of nested flux surfaces. The coils creating the field, embedded in the superconducting bulk, can be chosen with very simple shapes, in contrast with the cumbersome arrangements in current experiments, and can be spared from large magnetic forces between them. Because of the superconductor properties, the system will tend to maintain the optimum field distribution in response to instabilities in the plasma. We numerically demonstrate how a fully-confined magnetic field with the three-dimensional spatial distribution required in two of the most advanced stellarators, Large Helical Device and Wendelstein 7-X, can be exactly generated, using simple round coils as magnetic sources. Current high-temperature superconductors can be employed to construct the bulk superconducting toroid. This can lead to optimized robust magnetic confinement and largely simplified configurations in future fusion experiments.

Development of an APPLE III undulator prototype with three-dimensional force compensation for SHINE

The Shanghai high-repetition-rate XFEL and extreme light facility (SHINE) plans to install several elliptically polarizing undulators (EPUs) as afterburners behind the planar undulator section to obtain nearly saturated circularly polarized free-electron laser (FEL) radiation. Therefore, the SHINE R&D project needs to develop a 4-m-long EPU with an effective magnetic field of 1.5 T, a period of 68 mm, and a minimum gap of 3 mm. A magnetic force compensation EPU prototype has recently been built and tested at the Shanghai Synchrotron Radiation Facility (SSRF) based on the addition of permanent magnets. This prototype can realize magnetic compensation under various polarization modes in all working gaps, thereby reducing the deformation of the girders and maintaining sufficient rigidity of the mechanical structure. A girder deformation monitoring system was established to obtain real force compensation feedback. The final magnetic field measurement results meet the physical requirements, and the proposed scheme can be used as an alternative to the EPU with a high magnetic field and large magnetic force.

Investigation of heat and mass transfer for an MHD hybrid nanofluid flow over a rotating disk: a numerical investigation with supervised neural network

The key intention behind this research work is to investigate the heat and mass transfer phenomenon in the flow of hybrid nanofluid over a revolving disk with magnetohydrodynamic effects under consideration (MHD-HNRD). The flow model of the problem has been formulated in the form of PDEs which are further transmuted into ODEs with proper transforming equations. The influence of Magnetic parameter, Brinkman number, Prandtl number, Rotation parameter, and Concentration of the nanoparticles on velocities and thermal profile has been studied and reference data sets for the MHD-HNRD model are computed with the help of the renowned Lobatto-IIIA solver by varying these parameters. This reference solution is then subjected under the proposed solution methodology based on Levenberg–Marquardt Supervised Neural Networks (LMSNNs). An increase in heat transfer rate has been observed with the larger magnetic force and rotation rate. Graphical and numerical results based on mean-square errors (MSEs), time series response, error distribution plots, and regression plots endorse the precision, validity, and consistency of the proposed solution methodology. MSEs up to the level of 10–12 and performance learning curves predict the smoothness of the curves with the number of epochs confirming the accuracy, convergence, and validity of the designed solver.

Design of a 120 W Electromagnetic Shock Absorber for Motorcycle Applications

Based on the shock absorber size and power and power density limitations in motorcycle application, a linear permanent magnet machine for a regenerative suspension system that recovers the kinetic energy originating from shock absorber vibration is investigated. To achieve the target power of 120 W, several design parameters were investigated. The eight-slot eight-pole combination was used due to its high power density. A hybrid permanent magnet structure was implemented which was a combination of a classical Halbach array and iron spacers. In addition, the dimensions of the permanent magnet, and stator inner radius were parametrically studied to enhance the air-gap flux density and coil volume, which are the main factors affecting performance. The detailed design generated 124 W of average power under the rated condition, assuming a vibration speed of 0.157 m/s. Despite the satisfaction of the output power and power density, the large magnetic force caused by the interaction between the iron core and permanent magnet is the main drawback of this design, which has a negative impact on driving safety and comfort. To commercialize the suggested device, additional studies will focus on size, electromagnetic reduction, as well as road test performance.

Positioning of the coil and reduction of the first harmonic of the magnetic field in the superconducting cyclotron using support link forces

A high magnetic field in a superconducting cyclotron is associated with large magnetic forces acting on the magnet coils. These coils are placed in a position using support links that provide stability against the magnetic forces. However, the present configuration of our K500 superconducting cyclotron at VECC, Kolkata does not allow the superconducting coil to be centred with respect to pole tips. This causes field error and beam losses before extraction as observed in our superconducting cyclotron. An analytical model is developed to locate the optimal positioning of the superconducting coils based on support link forces. The present paper describes the methodology for positioning the superconducting coil that produces minimum field error and maintains a safe limit for link forces. Different analyses are presented and compared with experimental data of the superconducting cyclotron at VECC Kolkata.

Trapped magnetic field distribution above a superconducting linear Halbach array

In applications requiring a large magnetic force, permanent magnets with non-parallel magnetization directions can be assembled in a Halbach array to generate a large gradient of magnetic flux density. The saturation magnetization of permanent magnets, however, brings a fundamental limit on the performance of this configuration. In the present work, we investigate experimentally the assembly of cuboid bulk, large grain melt-textured YBa2Cu3O superconductors ( mm3) with orthogonal c-axes so as to form a basic unit of Halbach array. The experiments are carried out at 77 K. The experimental distribution of the magnetic flux density above the array of trapped-field superconductors is compared to a similar array made of permanent magnets. A simple analytical model is developed and is shown to accurately reproduce the main experimental observations. The results suggest that a redistribution occurs in the current flowing in the central sample when the distance between the superconductors is reduced, whereas the neighbouring superconductors are unaffected. It is shown that this current redistribution yields a reduced contribution of the central sample to the magnetic flux density above the centre of the array and a new negative contribution associated with stray fields to the magnetic flux density at this location. This interpretation is confirmed by modelling of the distribution of transport currents in the superconductor using a 3D finite element model.

Magnetic Circuit Analysis of Halbach Array and Improvement of Permanent Magnetic Adsorption Device for Wall-Climbing Robot

To solve the problems that the theoretical analysis of Halbach array magnetic circuit is insufficient and that calculating the magnetic adsorption force of a permanent magnet by using the magnetic node method is complex, the magnetic flux density of a Halbach array magnetic circuit composed of multiple permanent magnets with perpendicular magnetization directions is calculated. On the basis of the concentrated magnetic phenomenon of the ferromagnetic material and the end effect of the permanent magnet, a method for calculating the magnetic adsorption force of the Halbach array magnetic circuit by using the equivalent magnetic flux density is proposed, and the variation trend of magnetic adsorption force after changing the parameters of the magnetic circuit is obtained. ANSYS software is used to analyze several magnetic circuits that produce large magnetic adsorption force, a magnetic circuit structure that produces the largest magnetic adsorption force is determined, and the permanent magnetic adsorption device of the wall-climbing robot is improved. The magnetic adsorption force of the wall-climbing robot before and after the improvement of the permanent magnetic adsorption device is measured through experiments. The experimental results show that the magnetic adsorption force after the improvement is increased by 24.63% compared to before the improvement.

O025 Smart polymer implants as an emerging technology for treating airway collapse in obstructive sleep apnea: proof of concept

Abstract Study objectives To assess the use of a novel magnetic polymer implant in reversing airway collapse and identify potential anatomical targets for airway implant surgery in an in vivo porcine model. Methods Target sites of airway collapse were genioglossus muscle, hyoid bone, and middle constrictor muscle. Magnetic polymer implants were sutured to these sites, and external magnetic forces, through magnets with pull forces rated at 102 kg and 294 kg, were applied at the skin. The resultant airway movement was assessed via nasendoscopy. Pharyngeal plexus branches to the middle constrictor muscle were stimulated at 0.5 mA, 1.0 mA, and 2.0 mA and airway movement assessed via nasendoscopy. Results At the genioglossus muscles, large magnetic forces were required to produce airway movement. At the hyoid bone, anterior movement of the airway was noted when using a 294 kg rated magnet. At the middle constrictor muscle, an anterolateral (or rotatory) pattern of airway movement was noted when using the same magnet. Stimulation of pharyngeal plexus branches to the middle constrictor revealed contraction and increasing rigidity of the lateral walls of the airway as stimulation amplitude increased. The resultant effect was prevention of collapse as opposed to typical airway dilation, a previously unidentified pattern of airway movement. Conclusions Surgically implanted smart polymers are an emerging technology showing promise in the treatment of airway collapse in obstructive sleep apnea. Future research should investigate their biomechanical role as an adjunct to treatment of airway collapse through nerve stimulation.

Magnetic Polymers for Magnetophoretic Separation in Microfluidic Devices

Magnetophoresis offers many advantages for manipulating magnetic targets in microsystems. The integration of micro-flux concentrators and micro-magnets allows achieving large field gradients and therefore large reachable magnetic forces. However, the associated fabrication techniques are often complex and costly, and besides, they put specific constraints on the geometries. Magnetic composite polymers provide a promising alternative in terms of simplicity and fabrication costs, and they open new perspectives for the microstructuring, design, and integration of magnetic functions. In this review, we propose a state of the art of research works implementing magnetic polymers to trap or sort magnetic micro-beads or magnetically labeled cells in microfluidic devices.

Thermorheological properties of magnetorheological grease and its thermomagnetic coupling mechanism

A heating phenomenon exists in the service process of magneto-rheological devices. For magnetorheological devices using magnetorheological grease (MRG) as the working medium, changes in the medium’s rheological behaviors caused by temperature increase will generate challenges in the reliable service of the devices. With laboratory-prepared MRG as the research object, MRG rheological property laws under different temperatures and magnetic field intensities are investigated, and the magnetic properties of carbonyl iron (CI) powder under different temperatures are analyzed. The relationship between the evolution of the MRG structural system and changes in rheological properties under the action of thermomagnetic coupling is discussed. The results show that the MRG structural system is composed of base carrier liquid soap fibers and magnetic chains under the action of a magnetic field, and the soap fibers can strengthen the structural intensity of the MRG. A decrease in the entanglement degree of the soap fiber structure caused by temperature increase will obviously weaken the intensity of the entire MRG system and narrow the regulation and control scope of the MRG rheological properties. The structural evolution of soap fibers under thermomagnetic coupling will affect the chain formation of magnetic particles and ultimately their rheological properties. At low temperature and magnetic field intensity, the entanglement degree of soap fibers is relatively high, and the magnetic force on magnetic particles is weak, which cannot completely overcome the binding of soap fibers. The influence of soap fibers is the dominant factor affecting the MRG rheological properties. As temperature and magnetic field intensity increase, the entanglement degree of soap fibers decreases, magnetic particles gradually disperse from the soap fibers under the action of a large magnetic field force, and the magnetic chain structure gradually becomes the dominant factor affecting the MRG rheological properties. Moreover, the weakening degree of the temperature increase effect on the MRG rheological properties decreases, and the rheological law changes gradually.

268 Smart polymer implants as an emerging technology for treating airway collapse in OSA: a proof of concept study

Abstract Introduction Implantable 3D printed ‘smart’ polymers are an emerging technology with potential applications in treating collapse in adult obstructive sleep apnea through mechanical airway manipulation. There is a paucity of devices that are commercially available or in research and development stage. Limited studies have investigated the use of implantable smart polymers in reversing the collapsibility of the pharyngeal airway by creating counter forces during sleep. This paper describes an application of implantable magnetic polymer technology in an in-vivo porcine model. Study Objectives: To assess the use of a novel magnetic polymer implant in reversing airway collapse and identifying potential anatomical targets for airway implant surgery in an in-vivo porcine model. Methods Target sites of airway collapse were genioglossus muscle, hyoid bone and middle constrictor. Magnetic polymer implants were sutured to these sites and external magnetic forces, through magnets with pull forces rated at 102kg and 294kg, were applied at the skin. The resultant airway movement was assessed via nasendoscopy. Pharyngeal plexus branches to the middle constrictor muscle were stimulated at 0.5mA, 1.0mA and 2.0mA and airway movement assessed via nasendoscopy. Results At the genioglossus muscles large magnetic forces were required to produce airway movement. At the hyoid bone, anterior movement of the airway was noted when using a 294kg rated magnet. At the middle constrictor muscle, an anterolateral (or rotatory) pattern of airway movement was noted when using the same magnet. Stimulation of pharyngeal plexus branches to the middle constrictor revealed contraction and increasing rigidity of the lateral walls of the airway as stimulation amplitude increased. The resultant effect was prevention of collapse, a previously unidentified pattern of airway movement. Conclusion Surgically implanted smart polymers are an emerging technology showing promise in the treatment of airway collapse in obstructive sleep apnea. Future research should investigate their biomechanical role as an adjunct to treatment of airway collapse through nerve stimulation. Support (if any) Garnett-Passe and Rodney Williams Memorial Foundation, Conjoint Grant, 2016-18.

A conceptual study of a high gradient trapped field magnet (HG-TFM) toward providing a quasi-zero gravity space on Earth

In this work, we propose a new concept of a high gradient trapped field magnet (HG-TFM). The HG-TFM is made from (RE)BaCuO bulk superconductors, in which slit ring bulks (slit-TFMs) are tightly stacked with TFM cylinders (full-TFMs), and state-of-the-art numerical simulations were used to investigate the magnetic and mechanical properties in detail during and after magnetization. A maximum value of the magnetic field gradient product of = 6040 T2 m−1 was obtained after conventional field cooled magnetization (FCM) with an applied field, B app, of 10 T of the HG-TFM with 60 mm in outer diameter and 10 mm in inner diameter. This value may be the highest value ever reported compared to any other magnetic sources. The value increased with decreasing inner diameter of the HG-TFM and with increasing B app during FCM. The electromagnetic stress in the HG-TFM during the FCM process mainly results from the hoop stress along the circumferential direction. The simulations suggested that there is no fracture risk of the bulk components during FCM from 10 T in a proposed realistic configuration of the HG-TFM where both TFM parts are mounted in Al-alloy rings and the whole HG-TFM is encapsulated in a steel capsule. A quasi-zero gravity space can be realized in the HG-TFM with a high value in an open space outside the vacuum chamber. The HG-TFM device can act as a compact and cryogen-free desktop-type magnetic source to provide a large magnetic force and could be useful in a number of life/medical science applications, such as protein crystallization and cell culture.

Deep drawing with radial segmental blank holder based on magnetic control

<p indent=0mm>We propose a radial segmental blank holder technique based on the electro-permanent magnet (EPM) technology, in which we can obtain a more reasonable blank holding force (BHF). The magnetic pole unit was constructed according to the characteristics of soft magnetic materials and adjusted the magnetic state of the magnetic pole unit by an instantaneous low-intensity current. The tensile test revealed that the magnetic pole unit can provide a sufficiently large magnetic attraction force to satisfy the blank holding requirements. The measurement results of the temperature rise experiment verified that the magnetic pole unit would not cause overheating. According to the characteristics of the drawing process, the blank holder device and the drawing die based on EPM technology were designed. The BHF applied during the drawing process does not need to be continuously energized, so it has the advantages of energy-saving and safety. Theoretical derivation was used to determine the feasibility of the radial segmental blank holder technique and analyzed the initial distribution of the BHF on sheet metal using FEA. The results show that, compared with the conventional blank holder, we could implement the BHF applied by the new method in a larger radial area. We further verified the efficiency of the radial segmental blank holder technique by performing simulation. Since the BHF is more rationally distributed in the radial direction, we could control the sheet thickness variation better. Finally, the drawing experiment of the galvanized sheet revealed that the EPM technology is feasible for the blank holder, and the radial segmental blank holder technique can efficiently suppress wrinkling and enhance the performance.

Smart polymer implants as an emerging technology for treating airway collapse in obstructive sleep apnea: a pilot (proof of concept) study.

To assess the use of a novel magnetic polymer implant in reversing airway collapse and identify potential anatomical targets for airway implant surgery in an in vivo porcine model. Target sites of airway collapse were genioglossus muscle, hyoid bone, and middle constrictor muscle. Magnetic polymer implants were sutured to these sites, and external magnetic forces, through magnets with pull forces rated at 102 kg and 294 kg, were applied at the skin. The resultant airway movement was assessed via nasendoscopy. Pharyngeal plexus branches to the middle constrictor muscle were stimulated at 0.5 mA, 1.0 mA, and 2.0 mA and airway movement assessed via nasendoscopy. At the genioglossus muscles, large magnetic forces were required to produce airway movement. At the hyoid bone, anterior movement of the airway was noted when using a 294 kg rated magnet. At the middle constrictor muscle, an anterolateral (or rotatory) pattern of airway movement was noted when using the same magnet. Stimulation of pharyngeal plexus branches to the middle constrictor revealed contraction and increasing rigidity of the lateral walls of the airway as stimulation amplitude increased. The resultant effect was prevention of collapse as opposed to typical airway dilation, a previously unidentified pattern of airway movement. Surgically implanted smart polymers are an emerging technology showing promise in the treatment of airway collapse in obstructive sleep apnea. Future research should investigate their biomechanical role as an adjunct to treatment of airway collapse through nerve stimulation.

Structural modeling and validation of laminated stacks in magnetic gearing applications

Laminated structures are commonly employed in magnetic gears based on their ability to direct magnetic flux, while inhibiting eddy currents. Unfortunately, the stiffness of the laminated structure is much lower than a solid part, which can lead to unacceptable deflections, given the large magnetic forces and small air gaps in magnetic gears. Finite element analysis of laminations to accurately predict these deflections can be computationally expensive due to the small elements needed to model the thin lamination dimensions. These analyses also have some uncertainty due to the assignment of bonding stiffness. This paper presents a means of accurately modeling the deflection of a laminated stack with reduced complexity and computational time, which is compared to experimental results. The resulting methods are then used to assess the magnetic and mechanical advantages of different designs for the modulating pieces of a magnetic gear.

Hyperloop – prediction of social and physiological costs

Background: Hyperloop is a new technological concept for a very fast magnetic levitation train that would travel through soft vacuum tubes and could achieve a speed of up to 1,200 km/h. As a new transportation system, it might bring some challenges related to human factors that should be tested and considered when designing and propagating Hyperloop.&#x0D; Aim: This paper used literature review to identify potential physiological and social challenges. Some of these challenges might be high speed, high acceleration /deceleration, large magnetic forces, safety concerns, air pressure, motion sickness and cost as potential human-related challenges.&#x0D; Methods: In this case, the method of literature review aimed to evaluate the potential physiological effect of these factors on the passengers. It investigated physiological consequences of very high speed, high acceleration/deceleration, and a high magnetic field, as well as human factors of the Maglev trains.&#x0D; Results: The literature identified high acceleration/deceleration, high speed and high magnetic field as potential risks or sources of discomfort for the passengers.&#x0D; Conclusion: To the knowledge of the authors, it is the first attempt to identify social and physiological challenges related to the Hyperloop trains concept. It is aimed to inform the development and policies to achieve the safest and most comfortable transportation form.

Miniaturised SH EMATs for Fast Robotic Screening of Wall Thinning in Steel Plates

Electromagnetic acoustic transducers (EMATs) are well suited to generating and detecting a variety of different ultrasonic wavemodes, without the need for couplant, and they can be operated through some coatings. EMATs can be used to generate shear horizontal (SH) waves, which show promise for fast screening of wall thinning and other defects. However, commercial SH-wave EMATs are not suitable for robotic implementation on ferritic steel due to the large magnetic drag force from the magnets. This article describes the design and characterisation of miniaturised SH guided wave EMATs, which significantly reduce the magnetic drag and enable mounting onto a small crawler robot for sample scanning. The performance of the miniaturised EMATs is characterised and compared to a commercial EMAT. It is shown that signal to noise ratio is reduced, but remains within an acceptable range to use on steel. The bandwidth and directivity are increased, depending on the exact design used. Their ability to detect flat bottomed holes mimicking wall thinning is also tested.

Influence of copper damper on bifurcation vibration in superconductive magnetic levitation system

With proper external vibrations, the dynamic behavior of a high-temperature superconducting levitation system will show interesting bifurcation and complex chaos. In order to eliminate the effects of nonlinear vibrations, a larger magnetic force generated by a high-temperature superconductor (HTSC) with strong flux pinning is necessary. However, it provides minimal inherent damping. In this article, we numerically studied the effect of different copper damper arrangements on the superconductive magnetic levitation system in nonlinear vibration by the finite element method. Furthermore, we compared the results with and without a copper damper by analyzing the displacements, temperature differences, and electromagnetic forces (HTSC and copper). The results indicate that adjusting the copper damping can increase the interference rejection capacity of the superconductive magnetic levitation system.

Measurement and Analysis of Magnetic Properties of YBa2Cu3O7-y Bulk Superconductor

YBa2Cu3O7-y single crystal bulk high-temperature superconductor has high critical current density with large magnetic levitation and trapping magnetic forces. Despite its distinctive electromagnetic properties, the longtime heat treatment process of oxide high-temperature superconductor, a ceramic material, is widely considered as a factor that can degrade industrial applicability of superconductors seriously. For applications in power systems, metal-ceramic composites need to be fabricated to enhance magnetic performance. In this study, CeO2 was utilized as an additive to control Y211 particles and improve superconducting magnetic properties. The study achieved meaningful outcomes, given that it reduced the processing time by half (1/2) with the interior seeding technique, realized the effect of top seeding by positioning one additional seed layer on the top surface, and obtained a magnetic levitation force of 67.015 N. In order to improve the physical properties of superconducting materials, interior seeding technique was applied, and the effect of top seeding was obtained by placing one seed layer on the top surface. Therefore, when two seed layers were used to fabricate a specimen, it could improve physical properties of superconductors to the extent that both the top and bottom pellets could be used.

Mössbauer Spectroscopy and Magnetic Properties of Bi0.8Ca0.2-xSrxFeO3 Nanoparticles by Sol-Gel Method

Doping at A/B-sites can effectively improve the physical properties of perovskite ferrites. In this study, the performance of Bi0.8Ca0.2-xSrxFeO3 was investigated using the sol-gel autocombustion method. The results show that with an increase in x value, the grain size first increases and then decreases. With an increase in the doping concentration, the reunion phenomenon reduces, but the smoothness and flatness of the samples are also destroyed. Moreover, with increasing Sr2+ concentration, particle growth is inhibited, resulting in smaller particle sizes. When the Sr2+ concentration increases to a certain value, the environment becomes advantageous for particle growth and therefore the particle size increases. For x=0.13, small particles are obtained. With increasing Sr2+ concentration, the spatial modulation of the spin structure is destroyed, the lattice distorts, and the magnetic force is freed. Mössbauer spectrum measurements shows that when the Ca2+ concentration is greater than the Sr2+ concentration, Sr2+ ions replace Ca2+ ions; as a result, A-A magnetic superexchange diminishes, leading to a decrease in the hyperfine field. Appropriate doping of BiFeO3 can improve its coercivity and refine its grains and result in a larger magnetic force.