Design of Gradient Magnetic Field Coil Based on an Improved Particle Swarm Optimization Algorithm for Magnetocardiography Systems

Zhao, Fengwen; Zhou, Xiangyang; Xie, Xiaoxuan; Wang, Kai

doi:10.1109/tim.2021.3106677

Cited by 25 publications

(7 citation statements)

References 26 publications

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“…It is usually a multilayer magnetic shielding made of material with high permeability and suppresses the major stray magnetic field. The active components are compensation coils comprising triaxial uniform magnetic field coils and several gradient coils, which offset the remaining small part of the remnant magnetic induction [12,13].…”

Section: Introductionmentioning

confidence: 99%

A high-performance multilayer cylindrical magnetic shielding with a varying layer spacing for NMR sensors

Shaofeng

Liu

et al. 2023

Meas. Sci. Technol.

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A stable inner working environment is essential for NMR sensors, which requires the absence of remnant magnetic fields and fluctuations caused by the surrounding magnetic fields. In this study, we utilized analytical formulations to derive transverse and longitudinal magnetic shielding factors for multilayer cylindrical magnetic shielding. Subsequently, we proposed a novel method for designing and improving the shielding factor by optimizing the spacing of every pair of adjacent layers within a limited volume. The final design result of the multilayer cylindrical magnetic shielding features optimally designed varying layer spacing, which are associated with a specific length and diameter. After optimization, the transverse shielding factor increased by 5.53%, 8.99%, and 13.51% for the three-, four-, and five-layer shields, respectively, compared to traditional magnetic shielding. The opening in the axial center of the magnetic shielding barrel may cause leakage of the magnetic flux and inhomogeneous remnant magnetic induction. We introduced a stovepipe to the end cap of the axial shield based on the finite element method, resulting in an improvement in the homogeneity of remnant magnetic induction. This modification widened the axial uniform region of the innermost shielding layer by approximately 9 cm within 52.5 cm in our simulation. To implement our proposed optimization method, we established and manufactured a four-layer cylindrical magnetic shielding with stovepipes and varying layer spacing. Moreover, the results indicate that this optimal method works for other applications in which multilayer magnetic shielding is required.

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Section: Introductionmentioning

confidence: 99%

A high-performance multilayer cylindrical magnetic shielding with a varying layer spacing for NMR sensors

Shaofeng

Liu

et al. 2023

Meas. Sci. Technol.

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“…Triaxial uniform field coils are indispensable elements for the capture and manipulation of atoms in many quantum precision measurement devices. Examples of these devices include spin-exchange relaxation free (SERF) atomic magnetometers [1][2][3], nuclear magnetic resonance gyroscopes (NMRGs) [4], * Author to whom any correspondence should be addressed. magnetic resonance imaging devices [5,6], and atomic clocks [7].…”

Section: Introductionmentioning

confidence: 99%

“…Because of this problem, some researchers proposed the realization of in-situ measurement of the coil magnetic field using the atomic spin effect [18]. Zhang et al calibrated the coil magnetic field via extraction and analysis of the Larmor precession frequency of hyperpolarized 3 He in an atomic magnetometer [19]. Chen et al proposed acquisition of the coil magnetic field by measuring the π/2 pulse duration in an NMRG [4].…”

Section: Introductionmentioning

confidence: 99%

“…Chen et al proposed acquisition of the coil magnetic field by measuring the π/2 pulse duration in an NMRG [4]. However, these two methods require the use of noble gases such as 3 He and 129 Xe in the vapor cell, and thus they are not suitable for sensors that contain alkali metal atoms only and no noble gases. Subsequently, Zhang et al analyzed the electron paramagnetic resonance spectra of spin-polarized potassium atoms under various magnetic fields to establish a coil constant model [20].…”

Section: Introductionmentioning

confidence: 99%

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Analytical model for calculation of the magnetic field of triaxial uniform coils in magnetically shielded cylinder

Zhao¹,

Wang²,

Zhou³

et al. 2022

J. Phys. D: Appl. Phys.

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An analytical model to calculate the magnetic field of triaxial uniform coils inside magnetically shielded cylinders (MSCs) composed of high-permeability materials is proposed. The proposed model offers two major advantages over existing methods. First, the model is not limited to the research on coaxial circular coils, but also can be used to analyze the magnetic field characteristics of saddle coils inside MSCs. Second, based on Green’s function expansion and the ferromagnetic boundary conditions, the image method is introduced to consider the reflection effect of the MSC end cap on the coil, thus enabling the coupling effect between the coil and the MSC to be analyzed. To verify the model’s correctness, simulations and experiments are performed separately. With regard to the magnetic field distributions of the saddle coil and the Lee-Whiting coil within a range of ± 80 mm along their axes, the results show that the maximum relative error between the analytical method and the finite element method results is 0.08% and 0.06%, respectively; the maximum relative error between the experimental values and the analytical values is 0.29% and 0.13%, respectively, thus confirming the validity of the analytical model. The results of this research have far-reaching implications for the research of quantum precision measurement devices and triaxial uniform field coils.

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“…The gradient design methods can be divided into two categories depending on whether the coil is discrete [18] or distributed [19]- [23]. The distributed winding method is more flexible because the coil shapes do not need to be predetermined.…”

Section: Introductionmentioning

confidence: 99%

Gradient Coil Design Method Specifically for Permanent-magnet-type Low Field Portable MRI Brain Scanner

Kong

Shen

et al. 2022

IEEE Trans. Instrum. Meas.

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ferromagnetic structures, particularly the anti-eddy plate, in a bi-planar permanent-magnet-type low-field (0.05 T) magnetic resonance imaging (MRI) brain scanner can distort the gradient field in the target region. This study aims to provide a new gradient coil design method that reduces ferromagnetic influences on gradient field linearity. Thus, a simplified model of electromagnetic (EM) structures of the permanent-magnet-type MRI scanners was established. By using precise analytical proof, the anti-eddy plate was reduced to a homogeneous magnetic plate. The overall effects of the EM structures, which can be represented by bi-planar magnetic plates, were evaluated. In sequence, the image magnetic dipole was first introduced to show the effects of anti-eddy plates were added to the conventional equivalent magnetic dipole (EMD) approach. A novel equivalent image magnetic dipole (EIMD) method was proposed to build the gradient coil pattern. The effect of ferromagnetic materials was predicted throughout the gradient coil design phase using the proposed method, and a high-linear gradient field was generated under real working conditions. The computational and experimental results showed that the gradient coil was linear when ferromagnetic structures were present. The effectiveness of the proposed method was demonstrated by comparing T1-weighted images of the conventional method to those of the proposed method. The proposed method reduced image distortion caused by nearby EM structures in bi-planar permanent-magnet-type lowfield MRI systems and provided an effective and concise solution for gradient coil designs.

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Design of Gradient Magnetic Field Coil Based on an Improved Particle Swarm Optimization Algorithm for Magnetocardiography Systems

Cited by 25 publications

References 26 publications

A high-performance multilayer cylindrical magnetic shielding with a varying layer spacing for NMR sensors

A high-performance multilayer cylindrical magnetic shielding with a varying layer spacing for NMR sensors

Analytical model for calculation of the magnetic field of triaxial uniform coils in magnetically shielded cylinder

Gradient Coil Design Method Specifically for Permanent-magnet-type Low Field Portable MRI Brain Scanner

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