Minimum maximum temperature gradient coil design

Authors

  • Peter T. While,

    Corresponding author
    1. Department of Microsystems Engineering (IMTEK), Laboratory for Simulation, University of Freiburg, Freiburg, Germany
    • School of Mathematics and Physics, Faculty of Science, Engineering and Technology, University of Tasmania, Hobart, Tasmania, Australia
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  • Michael S. Poole,

    1. School of Information Technology and Electrical Engineering, Faculty of Engineering, Architecture and Information Technology, University of Queensland, St. Lucia, Brisbane, Queensland, Australia
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  • Larry K. Forbes,

    1. School of Mathematics and Physics, Faculty of Science, Engineering and Technology, University of Tasmania, Hobart, Tasmania, Australia
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  • Stuart Crozier

    1. School of Information Technology and Electrical Engineering, Faculty of Engineering, Architecture and Information Technology, University of Queensland, St. Lucia, Brisbane, Queensland, Australia
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Department of Microsystems Engineering (IMTEK), Laboratory for Simulation, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany. E-mail: peter.while@imtek.unifreiburg.de

Abstract

Ohmic heating is a serious problem in gradient coil operation. A method is presented for redesigning cylindrical gradient coils to operate at minimum peak temperature, while maintaining field homogeneity and coil performance. To generate these minimaxT coil windings, an existing analytic method for simulating the spatial temperature distribution of single layer gradient coils is combined with a minimax optimization routine based on sequential quadratic programming. Simulations are provided for symmetric and asymmetric gradient coils that show considerable improvements in reducing maximum temperature over existing methods. The winding patterns of the minimaxT coils were found to be heavily dependent on the assumed thermal material properties and generally display an interesting “fish-eye” spreading of windings in the dense regions of the coil. Small prototype coils were constructed and tested for experimental validation and these demonstrate that with a reasonable estimate of material properties, thermal performance can be improved considerably with negligible change to the field error or standard figures of merit. Magn Reson Med 70:584–594, 2013. © 2012 Wiley Periodicals, Inc.

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