| A portable Halbach magnet that can be opened and closed without force: the NMR-CUFF. | |
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MedLine Citation:
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PMID: 21036637 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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Portable equipment for nuclear magnetic resonance (NMR) is becoming increasingly attractive for use in a variety of applications. One of the main scientific challenges in making NMR portable is the design of light-weight magnets that possess a strong and homogeneous field. Existing NMR magnets can provide such magnetic fields, but only for small samples or in small regions, or are rather heavy. Here we show a simple yet elegant concept for a Halbach-type permanent magnet ring, which can be opened and closed with minimal mechanical force. An analytical solution for an ideal Halbach magnet shows that the magnetic forces cancel if the structure is opened at an angle of 35.3° relative to its poles. A first prototype weighed only 3.1 kg, and provided a flux density of 0.57 T with a homogeneity better than 200 ppm over a spherical volume of 5mm in diameter without shimming. The force needed to close it was found to be about 20 N. As a demonstration, intact plants were imaged and water (xylem) flow measured. Magnets of this type (NMR-CUFF = Cut-open, Uniform, Force Free) are ideal for portable use and are eminently suited to investigate small or slender objects that are part of a larger or immobile whole, such as branches on a tree, growing fruit on a plant, or non-metallic tubing in industrial installations. This new concept in permanent-magnet design enables the construction of openable, yet strong and homogeneous magnets, which aside from use in NMR or MRI could also be of interest for applications in accelerators, motors, or magnetic bearings. |
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Authors:
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Carel W Windt; Helmut Soltner; Dagmar van Dusschoten; Peter Blümler |
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Publication Detail:
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Type: Journal Article Date: 2010-10-30 |
Journal Detail:
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Title: Journal of magnetic resonance (San Diego, Calif. : 1997) Volume: 208 ISSN: 1096-0856 ISO Abbreviation: J. Magn. Reson. Publication Date: 2011 Jan |
Date Detail:
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Created Date: 2011-01-14 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9707935 Medline TA: J Magn Reson Country: United States |
Other Details:
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Languages: eng Pagination: 27-33 Citation Subset: IM |
Copyright Information:
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Copyright © 2010 Elsevier Inc. All rights reserved. |
Affiliation:
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ICG-3: Phytosphere, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany. c.windt@fz-juelich.de |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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