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A design for a permanent magnet system is proposed that generates spatially homogeneous, constant magnetic field gradients, thus creating conditions suitable for MRI without gradient coils and amplifiers. This is achieved by superimposing a…

Instrumentation and Detectors · Physics 2015-10-12 Peter Blümler

Objective. To develop methods to design the complete magnetic system for a truly portable MRI scanner for neurological and musculoskeletal (MSK) applications, optimized for field homogeneity, field of view (FoV) and gradient performance…

Purpose: To design a low-cost, portable permanent magnet-based MRI system capable of obtaining in vivo MR images within a reasonable scan time. Methods: A discretized Halbach permanent magnet array with a clear bore diameter of 27 cm was…

Medical Physics · Physics 2020-05-07 T. O'Reilly , W. M. Teeuwisse , D. de Gans , K. Koolstra , A. G. Webb

Access to and availability of MRI scanners is typically limited by their cost, siting and infrastructure requirements. This precludes MRI diagnostics, the reference standard for neurological assessment, in patients who cannot be transported…

Accelerator magnets made from blocks of permanent magnets in a zero-clearance configuration are known as Halbach arrays. The objective of this work is the fusion of knowledge from different measurement sources (material and field) and…

Computational Engineering, Finance, and Science · Computer Science 2024-11-15 Luisa Fleig , Melvin Liebsch , Stephan Russenschuck , Sebastian Schöps

Homogeneous magnetic fields can be generated through the strategic arrangement of permanent magnets. The Halbach array serves as a prominent example of an effective design following this principle. However, it is a two-dimensional approach…

Materials Science · Physics 2025-06-02 Ingo Rehberg , Peter Blümler

Mallinson's idea that some spin textures in planar magnetic structures could produce an enhancement of the magnetic flux on one side of the plane at the expense of the other gave rise to permanent magnet configurations known as Halbach…

Materials Science · Physics 2018-05-09 Miguel A. Marioni , Marcos Penedo , Mirko Baćani , Johannes Schwenk , Hans J. Hug

We present a design for producing precisely adjustable and alternating single-axis magnetic fields based on nested Halbach dipole pairs consisting of permanent magnets only. Our design allows for three dimensional optical and mechanical…

Instrumentation and Detectors · Physics 2018-11-12 Oleg Tretiak , Peter Blümler , Lykourgos Bougas

Portable low-cost MRI systems have the potential to enable point-of-care and timely MRI diagnosis, and to make this imaging modality available to routine scans and to underdeveloped areas. With simplicity, no maintenance, no power…

Medical Physics · Physics 2018-12-31 Shao Ying Huang , Zhi Hua Ren , Sergei Obruchkov , Jia Gong , Robin Dykstra , Wenwei Yu

Background: Calculation of the electric field induced by transcranial magnetic stimulation (TMS) in the brain requires accurate models of the stimulation coils. Reconstructing models from the measured magnetic fields of coils so far worked…

Other Quantitative Biology · Quantitative Biology 2021-12-30 Kristoffer Hougaard Madsen , Maria Drakaki , Axel Thielscher

We present a target field approach to analytically design magnetic fields using permanent magnets. We assume that their magnetisation is bound to a two-dimensional surface and is composed of a complete basis of surface modes. By posing the…

Applied Physics · Physics 2024-05-24 Peter J. Hobson , Chris Morley , Alister Davis , Thomas Smith , Mark Fromhold

Purpose: One of the intrinsic limitations of low-field MRI is low signal-to-noise ratio (SNR), which can be further reduced by electromagnetic interference (EMI) due to the lack of a Faraday shielded room. To address this issue, we propose…

Medical Physics · Physics 2025-10-02 Jules Vliem , Najac Chloe , Beatrice Lena , Andrew Webb , Irena Zivkovic

We have developed a fast method to design perpendicular permanent magnets for simplifying stellarator coils based on existing codes. Coil complexity is one of the main challenges for stellarators. To date, only electromagnetic coils have…

Plasma Physics · Physics 2020-05-13 Caoxiang Zhu , Michael Zarnstorff , David Gates , Arthur Brooks

Halbach magnets are a source of homogeneous magnetic field in an enclosed volume while keeping stray fields at a minimum. Here, we present the design, construction, and characterization for a 10 cm inner diameter double Halbach ring…

Instrumentation and Detectors · Physics 2021-02-24 Arne Wickenbrock , Huijie Zheng , Georgios Chatzidrosos , Joseph Shaji Rebeirro , Tim Schneemann , Peter Bluemler

'Coil design' is an inverse problem in which arrangements of wire are designed to generate a prescribed magnetic field when energized with electric current. The design of gradient and shim coils for magnetic resonance imaging (MRI) are…

Classical Physics · Physics 2010-02-19 Michael Poole , Pierre Weiss , Hector Sanchez Lopez , Michael Ng , Stuart Crozier

We describe the design, assembly, and testing of a magnet intended to deflect beams of paramagnetic nanoclusters, molecules, and atoms. It is energized by high-grade permanent neodymium magnets. This offers a convenient option in terms of…

Instrumentation and Detectors · Physics 2020-05-26 Jiahao Liang , Thomas M. Fuchs , Rolf Schäfer , Vitaly V. Kresin

This review is a compilation of relevant concepts in designing Halbach multipoles for magnetic resonance applications. The main focus is on providing practical guidelines to plan, design and build such magnets. Therefore, analytical…

Instrumentation and Detectors · Physics 2023-11-20 Peter Blümler , Helmut Soltner

The gradient technique is a promising tool with theoretical foundations based on the fundamental properties of MHD turbulence and turbulent reconnection. Its various incarnations use spectroscopic, synchrotron, and intensity data to trace…

Astrophysics of Galaxies · Physics 2024-06-04 Alex Lazarian , Ka Ho Yuen , Dmitri Pogosyan

We present a design and the optimization of an irregular-shaped ring-pair magnet array that generates a 1D monotonic field pattern for 2D head imaging in a low-field portable MRI system. The magnet rings are discretized into fan-shaped ring…

Medical Physics · Physics 2019-01-08 Zhi Hua Ren , Jia Gong , Shao Ying Huang

This study proposes a versatile and efficient optimisation method for discrete coils that induce a magnetic field by their steady currents. The prime target is gradient coils for MRI (Magnetic Resonance Imaging). The derivative (gradient)…

Medical Physics · Physics 2024-04-02 Toru Takahashi
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