Four- and eight-piece Halbach array analysis and geometry optimisation for maglev

Han, Qinghua; Ham, Chan; Phillips, Ron

doi:10.1049/ip-epa:20045059

Cited by 23 publications

(7 citation statements)

References 13 publications

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“…A linear Halbach array can be easily fabricated using multiple magnets with alternating orientations. The simplest example of a Halbach array is a refrigerator magnet, which allows augmentation of the magnetic field on one side while canceling the field on the other side. , Figure shows a magnetic field simulated by using COMSOL Multiphysics for a linear Halbach array generated from several discrete magnets. Compared with the field of a normal cubic magnet, the main characteristics of a Halbach array are (i) the poles of a Halbach array are on the same side, which are different from a common cubic magnet with south and north poles on opposite sides; (ii) an enhanced periodic magnetic field is generated on the top (strong) side while the field is mostly canceled on the bottom (weak) side; (iii) the direction of the magnetic field on the top side shows periodic change from vertical to horizontal with complex orientations in between; and (iv) the field gradient is large in regions of horizontal field near the array.…”

Section: Resultsmentioning

confidence: 99%

Assembly and Photonic Properties of Superparamagnetic Colloids in Complex Magnetic Fields

Han

et al. 2011

Langmuir

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Interparticle magnetic dipole force has been found to drive the formation of dynamic superparamagnetic colloidal particle chains that can lead to the creation of photonic nanostructures with rapidly and reversibly tunable structural colors in the visible and near-infrared spectrum. Although most studies on magnetic assembly utilize simple permanent magnets or electromagnets, magnetic fields, in principle, can be more complex, allowing the localized modulation of assembly and subsequent creation of complex superstructures. To explore the potential applications of a magnetically tunable photonic system, we study the assembly of magnetic colloidal particles in the complex magnetic field produced by a nonideal linear Halbach array. We demonstrate that a horizontal magnetic field sandwiched between two vertical fields would allow one to change the orientation of the particle chains, producing a high contrast in color patterns. A phase transition of Fe(3)O(4)@SiO(2) particles from linear particle chains to three-dimensional crystals is found to be determined by the interplay of the magnetic dipole force and packing force, as well as the strong electrostatic force. While a color pattern with tunable structures and diffractions can be instantly created when the particles are assembled in the form of linear chains in the regions with vertical fields, the large field gradient in the horizontal orientation may destabilize the chain structures and produces a pattern of 3D crystals that compliments that of initial chain assemblies. Our study not only demonstrates the great potential of magnetically responsive photonic structures in the visual graphic applications such as signage and security documents but also points out the potential challenge in pattern stability when the particle assemblies are subjected to complex magnetic fields that often involve large field gradients.

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Section: Resultsmentioning

confidence: 99%

Assembly and Photonic Properties of Superparamagnetic Colloids in Complex Magnetic Fields

Han

et al. 2011

Langmuir

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“…While the magnetization axis of an ideal Halbach array rotates smoothly, in practice, a period of a Halbach array can be approximated from four magnets arranged so that the magnetization axis of each magnet is rotated 90 • to the magnet placed before it. 16 In the assembly proposed in Ref. 12, a three-quarter section of a Halbach array period, in the back-to-back configuration described above, is used to produce a magnetic field that is confined and concentrated to the center of the assembly.…”

Section: Magnet Assemblymentioning

confidence: 99%

An ultra-stable 1.5 tesla permanent magnet assembly for qubit experiments at cryogenic temperatures

Adambukulam,

Sewani,

Stemp

et al. 2020

Preprint

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Magnetic fields are a standard tool in the toolbox of every physicist, and are required for the characterization of materials, as well as the polarization of spins in nuclear magnetic resonance or electron paramagnetic resonance experiments. Quite often a static magnetic field of sufficiently large, but fixed magnitude is suitable for these tasks. Here we present a permanent magnet assembly that can achieve magnetic field strengths of up to 1.5 T over an air gap length of 7 mm. The assembly is based on a Halbach array of neodymium (NdFeB) magnets, with the inclusion of the soft magnetic material Supermendur to boost the magnetic field strength inside the air gap. We present the design, simulation and characterization of the permanent magnet assembly, measuring an outstanding magnetic field stability with a drift rate of < 1.7 ppb/h. Our measurements demonstrate that this assembly can be used for spin qubit experiments inside a dilution refrigerator, successfully replacing the more expensive and bulky superconducting solenoids.

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“…As the size of the magnetic flux density of the permanent magnet Halbach array determines the size of the braking force, the optimization index can be selected as: where M P M is the permanent magnets mass per unit area [20], which can be computed as:…”

Section: Geometric Structure Optimization Design Of Permanent Magnetmentioning

confidence: 99%

Design of Double-Sided Linear Permanent Magnet Eddy Current Braking System

Chen¹,

Tan²,

Li³

et al. 2017

PIER M

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Abstract-This work tries to design an Eddy current braking system that can brake at a very high speed within a short time or a short distance. In order to maximize the braking force and reduce lateral forces that can cause track deformation or damage, a double-sided linear permanent magnet Halbach array is proposed in this paper. Two possible designs (Type I and Type II) have been investigated. By using mathematic models, Finite Element Method (FEM) and experimental results, Type I design of a double-sided linear permanent magnet Halbach array is selected. Compared with the other design, Type I design can provide a much larger braking force. Moreover, the analysis also shows that the mathematic models can well capture the characteristic of Type I design. Thus these models are used to design a set of optimal design parameters such as the length and thickness of permanent magnet block to maximize flux density and braking force per unit mass of permanent magnets. The optimal performance is validated by using FEM.

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Four- and eight-piece Halbach array analysis and geometry optimisation for maglev

Cited by 23 publications

References 13 publications

Assembly and Photonic Properties of Superparamagnetic Colloids in Complex Magnetic Fields

Assembly and Photonic Properties of Superparamagnetic Colloids in Complex Magnetic Fields

An ultra-stable 1.5 tesla permanent magnet assembly for qubit experiments at cryogenic temperatures

Design of Double-Sided Linear Permanent Magnet Eddy Current Braking System

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