Design and manufacturing method of permanent magnet shimming coil for compensating magnetic susceptibility
A shim coil and design method technology, applied in the direction of measuring magnetic variables, measuring devices, instruments, etc., can solve the problems of being difficult to fully apply, occupying a large space, and requiring high power consumption, and achieve small size, high space utilization, and The effect of low power consumption
Active Publication Date: 2020-05-05
XIAMEN UNIV
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Problems solved by technology
The above improved shimming coils and methods require multiple sets of coils to cooperate with the adjustment of multiple sets of constant current sources to achieve shimming. The overall space occupied is large, the required power consumption is high, and most of them are improved designs of columnar coils, which are difficult to fully apply to planes. However, there are no literature reports on shim coils used to compensate the magnetic susceptibility effects of small-scale nuclear magnetic resonance spectrometers, multi-objective optimization design methods, and classification method minimum interference connecting lines.
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[0056] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.
[0057] The permanent magnet shim coils involved in compensating magnetic susceptibility in this embodiment are as follows: figure 1 , figure 2 As shown, the coil is in the form of a double plane, which is divided into left and right planes. The coil winding shapes on the two planes are different, and are composed of multiple clusters of irregular ring wire groups, and each plane coil is not symmetrical as a whole. .
[0058] In addition, the present invention also proposes a method for designing the shim coil, the process of which is as follows image 3 As shown, the above method is based on the following design:
[0059] The probe part of a small NMR spectrometer is usually relatively compact, and the disturbance effect of the surrounding non-zero magnetic susceptibility medium on the main magnetic field in the sample area is sufficient to...
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The invention provides a design and manufacturing method of a permanent magnet shimming coil for compensating magnetic susceptibility. The design method comprises the following steps: 1, establishinga magnetic susceptibility model in a shimming area; 2, calculating a non-uniform magnetic field caused by the magnetic susceptibility in the shimming area; 3, selecting a shimming coil carrying surface position, and setting an initial condition; 4, establishing a multi-objective optimization function, and setting a weight coefficient of each objective item; 5, setting a weight coefficient initialvalue and a target item convergence condition, and carrying out optimization solution by utilizing a Gilonov regularization and least square method; and 6, if each target item reaches a convergence condition, outputting a design result, otherwise, adjusting a weight parameter, and returning to the step 5. The manufacturing method comprises the following steps of: 1, classifying the conductor groups according to the sizes, the number of turns and the position characteristics of the multi-cluster annular conductor groups; 2, performing path optimization on connection of the annular coils, and reducing interference. By applying the technical scheme, the magnetic susceptibility disturbance field can be effectively compensated.
Description
technical field [0001] The invention relates to the field of miniaturized nuclear magnetic resonance spectrometers, in particular to a design and manufacturing method of a permanent magnet shim coil for compensating magnetic susceptibility. Background technique [0002] The factors that affect the uniformity of the magnetic field of the NMR spectrometer mainly include the inhomogeneity of the main magnet and the magnetic susceptibility of the surrounding area of the sample. The main magnet system of conventional nuclear magnetic resonance spectrometers is equipped with room temperature shim coils to improve the uniformity of the main magnetic field. The specific magnetic field generated by each set of shim coils corresponds to a harmonic item of the spherical harmonic expansion of the main magnetic field. Therefore, nuclear magnetic spectrometers are usually equipped with several or even dozens of sets of shim coils to eliminate each harmonic item of the main magnetic fiel...
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IPC IPC(8): G01R33/383
CPCG01R33/383
Inventor 孙惠军李情姚凯文刘敏郑振耀燕伟跃
Owner XIAMEN UNIV