Magnetic Coil Design Research Articles

Realization of an Optimized Cylindrical Uniform Magnetic Field Coil via the Flexible Printed Circuit Technology

Abstract The design and fabrication method of magnetic field coils with high uniformity is essential for atomic magnetometers. In this paper, a novel design strategy for cylindrical uniform coils is first proposed, which combines the target-field method (TFM) with an optimized slime mold algorithm (SMA) to determine optimal structure parameters. Then, the realization method for the designed cylindrical coil by using the flexible printed circuit (FPC) technology is presented. Compared with traditional fabrication methods, this method has advantages in excellent flexibility and bending property, making the coils easier to be arranged in limited space. Moreover, the manufacturing process of the FPC technology via a specific cylindrical uniform magnetic field coil is discussed in detail, and the successfully realized coil is well tested in a verification system. By comparing the uniformity performance of the experimental coil with the simulation one, the effectiveness of the FPC technology in producing cylindrical coils has been well validated.

Optimal design of uniform magnetic field coils within irregular magnetic shielding based on coupled SNOPT-finite element method analysis

Optimal design of uniform magnetic field coils within irregular magnetic shielding based on coupled SNOPT-finite element method analysis

Passive magnetic coil design for electromagnetic interference evaluation of axle counters

Measurement of magnetic fields near the railway tracks is crucial to ensure compatibility with the operation of axle counters. According to EN 50592 standard, the magnetic field is detected with a passive magnetic coil and an oscilloscope. From previous studies, in general, there has been no in-depth analysis of how the choice of coil winding parameters could affect the coil output voltage, which then affect the measurement sensitivity, in particular the coil design based on the standard and it is applicability for electromagnetic interference (EMI) evaluation of axle counters. Therefore, this paper will explore the design of a passive magnetic coil to obtain the optimum coil output voltage within the frequency range. Simulations showed that for 10-100 kHz and 100 kHz–1.3 MHz range, the optimum number of turns happened at 60-100 and 15-60 turns, respectively. Based on that, two example coils had been built. Simulations and measurements of their frequency response were in good agreement, with a deviation less than 1.0 dB.

Design of Uniform Magnetic Field Coil With Off-Center Target Region Based on Slime Mold Algorithm for Atomic Magnetometers

Design of Uniform Magnetic Field Coil With Off-Center Target Region Based on Slime Mold Algorithm for Atomic Magnetometers

Design of Transcranial Magnetic Stimulation Coils With Optimized Stimulation Depth

Design of Transcranial Magnetic Stimulation Coils With Optimized Stimulation Depth

Magnetic Field Coil Design Based on Distributed Taylor Expansion: Toward Large Uniform Area With High Orthogonality and Self-Shielding Feature

Magnetic Field Coil Design Based on Distributed Taylor Expansion: Toward Large Uniform Area With High Orthogonality and Self-Shielding Feature

Global optimal design of longitudinal gradient magnetic field coils based on a modified PSO algorithm in micro atomic sensors

Global optimal design of longitudinal gradient magnetic field coils based on a modified PSO algorithm in micro atomic sensors

Design of new resonant magnetic perturbation coils on the J-TEXT tokamak

The resonant magnetic perturbation (RMP) system is a powerful auxiliary system on tokamaks. On the J-TEXT tokamak, a set of new in-vessel coils is designed to enhance the amplitude of the RMP. The new coils are designed to be two-turn saddle coils. These two-turn saddle coils have been optimized in terms of their structure, support, and protection components to overcome the limitations of the narrow in-vessel space, resulting in a compact coil module that can be accommodated in the vessel. To verify the feasibility of this design, an electromagnetic simulation is performed to investigate the electrical parameters and the generated field of the coils. A multi-field coupled simulation is performed to investigate the capacity of heat dissipation. As a result of these efforts, the new RMP coils have been successfully installed on the J-TEXT tokamak. It has significantly enhanced the RMP amplitude and been widely applied in experiments.

Structural optimization design and numerical analysis of in-vessel magnetic compression coils

An FRC (field reversed configuration) device HUST-FRC (HFRC) is under construction at Huazhong University of Science and Technology, and the magnetic compression experiments will be investigated. 22 compression coils installed inside the metal vacuum chamber are designed with a peak current of about 110 kA rising within 50 μs. The coils are subjected to large electromagnetic forces during the compression process, which will challenge the structural stability of the coils. Therefore, it is necessary to estimate the structural stability of the compression coils during the compression progress. The compression process involves complex physical problems such as the coupling of circuit-electromagnetic-thermal-mechanical and non-linear contacts between adjacent coil components. It is also a challenge to calculate the coil current, electromagnetic load, and structure stress. To solve these problems, a joint analysis method is developed based on a two-dimensional (2-D) circuit-electromagnetic-thermal model and a three-dimensional (3-D) electromagnetic-mechanical model. The submodeling method is employed in mechanical simulations to improve the efficiency of coil optimization design. The electromagnetic and mechanical results confirm that the design of the compression coils is valid and feasible.

Design and evaluation of a rodent-specific focal transcranial magnetic stimulation coil with the custom shielding application in rats.

Repetitive TMS has been used as an alternative treatment for various neurological disorders. However, most TMS mechanism studies in rodents have been based on the whole brain stimulation, the lack of rodent-specific focal TMS coils restricts the proper translation of human TMS protocols to animal models. In this study, we designed a new shielding device, which was made of high magnetic permeability material, to enhance the spatial focus of animal-use TMS coils. With the finite element method, we analyzed the electromagnetic field of the coil with and without the shielding device. Furthermore, to assess the shielding effect in rodents, we compared the c-fos expression, the ALFF and ReHo values in different groups following a 15 min 5 Hz rTMS paradigm. We found that a smaller focality with an identical core stimulation intensity was achieved in the shielding device. The 1 T magnetic field was reduced from 19.1 mm to 13 mm in diameter, and 7.5 to 5.6 mm in depth. However, the core magnetic field over 1.5 T was almost the same. Meanwhile, the area of electric field was reduced from 4.68 cm2 to 4.19 cm2, and 3.8 mm to 2.6 mm in depth. Similar to this biomimetic data, the c-fos expression, the ALFF and ReHo values showed more limited cortex activation with the use of the shielding device. However, compared to the rTMS group without the shielding application, more subcortical regions, like the striatum (CPu), the hippocampus, the thalamus, and the hypothalamus were also activated in the shielding group. This indicated that more deep stimulation may be achieved by the shielding device. Generally, compared with the commercial rodents' TMS coil (15 mm in diameter), TMS coils with the shielding device achieved a better focality (~6 mm in diameter) by reducing at least 30% of the magnetic and electric field. This shielding device may provide a useful tool for further TMS studies in rodents, especially for more specific brain area stimulation.

Simulation design and experimental study of magnetic stimulation coil for robot pigeon

To explore the feasibility of applying magnetic stimulation technology to the movement control of animal robots, the influence of coil radius, number of turns and other factors on the intensity, depth and focus of magnetic stimulation was simulated and analyzed for robot pigeons. The coil design scheme was proposed. The coil was placed on the head and one of the legs of the pigeon, and the leg electromyography (EMG) was recorded when magnetic stimulation was performed. Results showed that the EMG was significantly strengthened during magnetic stimulation. With the reduction of the output frequency of the magnetic stimulation system, the output current was increased and the EMG was enhanced accordingly. Compared with the brain magnetic stimulation, sciatic nerve stimulation produced a more significant EMG enhancement response. This indicated that the magnetic stimulation system could effectively modulate the functions of brain and peripheral nerves by driving the coil. This study provides theoretical and experimental guidance for the subsequent optimization and improvement of practical coils, and lays a preliminary theoretical and experimental foundation for the implementation of magnetic stimulation motion control of animal robots.

Design of Compact Self-Shielded Uniform Magnetic Field Coils Based on Multipole Moment Optimization

Design of Compact Self-Shielded Uniform Magnetic Field Coils Based on Multipole Moment Optimization

Design of Biplanar Excitation Magnetic Field Coils With Small-Size and Large Uniform Area in Near-Zero Magnetic Cell Incubator

Low-frequency excitation magnetic field coils are potent tools for studying the effects of magnetic fields on cells. However, the existing excitation magnetic field coils are vulnerable to external magnetic fields and difficult to generate a high uniform excitation magnetic field with a small size. Thus, this study proposes a novel optimization design method combining the target field method (TFM), thickness mirror image method, and fruit fly optimization algorithm (FOA) to design a new type of bi-planar excitation magnetic field coil placed in a near-zero magnetic cell incubator. Based on the optimization design method, three bi-planar coils of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_x</i> , <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_y</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_z</i> with the paralleled arrangement in a near-zero magnetic cell incubator with the size of 365 mm × 336 mm × 200 mm were designed and measured. The coil constants of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_x</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_y</i> ) and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_z</i> are 8860 nT/A and 100640 nT/A, respectively. The non-uniformity of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_x</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_y</i> ) and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_z</i> coils are less than 5% and 1% over the central volume of 80 × 80 × 80 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , 100 × 100 × 100 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , respectively, meeting the most requirement of working space and the amplitude of magnetic field for cell research.

Toroidal magnetic field ripple in the presence of misaligned toroidal field coils on the COMPASS-U tokamak

Homogeneity of the toroidal magnetic field is a critical aspect of the tokamak fusion device. It is affected by the design of toroidal magnetic field coils and their manufacturing and assembly misalignments. The magnetic field of the COMPASS-U project is analysed using toroidal field ripple quantity. ANSYS modelling of bitter-plate-designed toroidal field coils is performed to prepare an accurate simplistic representation of the coils using a virtual current line. Toroidal field ripple is analysed using a Gaussian distribution of possible misalignments. The worst-case toroidal field ripple corresponding to the technical drawings only slightly exceeds the chosen limit of 0.5%.

Design of Uniform Magnetic Field Coil by Quasi-Elliptic Function Fitting Method With Multiple Optimizations in Miniature Atomic Sensors

This article presents a design method of cylindrical uniform field coil based on quasi-elliptic function fitting (EFF) method with multiple optimizations. The EFF method is a type of discrete wire techniques aiming at simplifying the coil structure. Combing with particle swarm optimization (PSO) algorithm, the optimized parameters of EFF coil are obtained for highly uniform magnetic field. To further improve the uniformity of magnetic field in the central space, a new regional points selection optimization method is proposed. The calculation results show that after PSO optimization, the absolute maximum relative error in the target region is optimized to 0.098% by EFF coil comparing with modified single saddle coil (3.08%), nest coil (2.4%), and target field method (TFM) coil (0.11%). After regional points selection optimization, the volume proportion of absolute magnetic field relative error less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1\times 10^{-4}$</tex-math></inline-formula> increases from 35.24% to 54.38% by EFF coil comparing with TFM coil. In addition, the simple EFF coil structure is verified to be easy to process and keep high performance through experiments. As the EFF coil’s high uniformity and simple structure, the new method has important significance for the miniaturization of atomic sensors.

Comparative study on HTS magnet coil design approach for 1.0 T @ 65 K with 10 ppm field homogeneity at 80 mm DSV

A comparative study is carried out between two distinct coil design approaches (Multi-coil and Compensated solenoid) for the development of 1.0 T REBCO main magnet coil suitable for Extremity Magnetic Resonance Imaging (E-MRI). The design includes a operating temperature of 65 K, for the enhancement of Ic with field anisotropy of REBCO tape. Each magnet design consists of HTS tape wound in the form of double pancake coils, having the inner winding diameter as 200 mm, whereas both outer diameter and magnet length are restricted to less than 400 mm. The two coils configurations are compared by keeping the bore inner diameter, outer diameter, length and fixed HTS tape length constant. Thereafter the parameters such as peak flux density, maximum radial field, stray field distribution, coil stress and field homogeneity for 80 mm diameter of spherical volume (DSV) are analyzed. Multi-coil design gives a better field homogeneity (315 ppm) as compared to Compensated solenoid.

Optimal design of transcranial magnetic stimulation coil with iron core

Objective. Iron core coils offer a passive way to increase the induced electric field intensity during transcranial magnetic stimulation (TMS), but the influences of core position and dimensions on coil performance have not been elaborately discussed before. Approach. In this study, with the basic figure-of-eight (Fo8) and slinky coil structures, iron core coil optimization is performed with the finite element method considering core position and dimensions. A performance factor combining performance parameters, including the maximum induced electric field, stimulation depth, focus, and heat loss, is utilized to evaluate the comprehensive coil performance. Main results. According to the performance factor, both iron core coils obtain the best overall performance with a fill factor 0.4 and the two legs of the iron core close to the inner sides of the coil. Finally, three prototypes are constructed—the basic, optimized, and full-size slinky iron core coil—and magnetic field detection demonstrates a good agreement with the simulation results. Significance. The proposed systematic optimization approach for iron core coil based on Fo8 and slinky basic structure can be applied to improve TMS coil performance, reduce power requirements, and guide the design of other iron core TMS coils.

Design of Transcranial Magnetic Stimulation Coils for Mouse With Improved Stimulus Focus and Intensity

Transcranial magnetic stimulation (TMS) is a noninvasive and painless treatment for some neurological or psychiatric disorders. The rodent model of TMS provides the possibility to reveal the mechanism of TMS at cellular and molecular levels. However, their application has been hampered by lack of stimulation coils with appropriate focus and intensity. In this study, we analyzed various forms of coils and proposed conductive shield and iron core materials to improve the coil performance. The results showed that the combination of “Halo” coil and “Figure of Eight” coil with shield and iron core could generate better stimulus focus (30.44 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) and intensity (87.6 V/m).

Magnetic coil design of steady magnetic field test facility for Tokamak complex

The most electrical equipment could be failure during the normal operating if they are exposed to the steady magnetic field which is beyond several mT (milli tesla), especially for the component installed around the Tokamak complex. Thus, these components which need to installed in such area must be tested in advance in order to verify the immunity property of steady magnetic field. This paper introduces a test facility which can be used to test the component. The test volume is 2.1 m3, the magnetic induction is 120 mT. At last, the test results for this facility are provided, it shows that the deviation between simulation and experiment are only 1% and used for immunity test of steady magnetic field for electrical equipment.

Design, simulation, and test of surface and volume radio frequency coils for 13C magnetic resonance imaging and spectroscopy.

Hyperpolarized 13C Magnetic Resonance (MR) is a promising technique for in vivo non-invasive assessment of metabolism in humans. Despite the considerable signal increase provided by hyperpolarization techniques, the low molar concentration of derivate 13C metabolites gives rise to technological limits in terms of data quality. The development of dedicated radio frequency coils, capable of providing a large field of view with high signal-to-noise ratio data, is thus a fundamental task. This work describes the design, simulation, and test of a surface and a volume coil, both designed to be integrated with a clinical scanner for hyperpolarized 13C studies in small animal models, with the purpose to provide a detailed characterization and comparison of their performance. In particular, coil inductance was evaluated with analytical calculation, while the magnetostatic theory was employed for coils magnetic field pattern estimation. Workbench tests permitted us to characterize coil performance in terms of quality factor and efficiency. Additionally, this Tutorial summarizes the acquisition experience for the reconstruction of 13C spectroscopic maps in phantom using the two designed coils and a 3T MR clinical scanner. We believe that this Tutorial could be interesting for graduate students and researchers in the field of magnetic resonance coil design and development, especially for 13C studies.