The ferrite phase shifter (FPS) is a microwave device that utilizes the gyromagnetic properties of ferrite materials to achieve phase shift. It offers advantages such as fast switching speed, low insertion loss (IL), and high reliability, making it widely used in phased array antenna (PAA) systems. However, the power handling capability (PHC) of Ku-band FPSs remains inadequate, limiting their application in high-power microwave (HPM) phased array systems. Based on the theory of ferrite gyromagnetism and the structure of the latching non-reciprocal FPS, this article derives a transcendental equation for the phase constant of the device. Expressions for the internal field distribution and power distribution are obtained. The interrelationships among phase-shifting efficiency, PHC, and various structural parameters are analyzed, leading to recommended value ranges for the structural parameters of high-power FPSs, thereby providing a theoretical foundation for phase shifter (PS) design. The ferrite material is another critical factor influencing the PHC. The high-power quality factor of the ferrite material is introduced, serving as a criterion for material selection. On this basis, the design, optimization, and development of a latching non-reciprocal double-toroid FPS have been completed. Through appropriate selection of structural parameters, improvement of ferrite material properties, and enhanced integration techniques, the PHC of the Ku-band FPS has been increased to over 500 kW, with an IL of less than 1.3 dB and a maximum differential phase shift (MDPS) of approximately 400°.
{"title":"Research on the Power-Handling Capability of Latching Non-Reciprocal Ferrite Phase Shifters","authors":"Xianggang Hu;Jiancang Su;Yue Ying;Mei Li;Rui Li;Jie Cheng;Shaotong Wu;Min Guo;Haichuan Zhang;Qi Wang;Fengzi Liu","doi":"10.1109/TMAG.2025.3646997","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3646997","url":null,"abstract":"The ferrite phase shifter (FPS) is a microwave device that utilizes the gyromagnetic properties of ferrite materials to achieve phase shift. It offers advantages such as fast switching speed, low insertion loss (IL), and high reliability, making it widely used in phased array antenna (PAA) systems. However, the power handling capability (PHC) of Ku-band FPSs remains inadequate, limiting their application in high-power microwave (HPM) phased array systems. Based on the theory of ferrite gyromagnetism and the structure of the latching non-reciprocal FPS, this article derives a transcendental equation for the phase constant of the device. Expressions for the internal field distribution and power distribution are obtained. The interrelationships among phase-shifting efficiency, PHC, and various structural parameters are analyzed, leading to recommended value ranges for the structural parameters of high-power FPSs, thereby providing a theoretical foundation for phase shifter (PS) design. The ferrite material is another critical factor influencing the PHC. The high-power quality factor of the ferrite material is introduced, serving as a criterion for material selection. On this basis, the design, optimization, and development of a latching non-reciprocal double-toroid FPS have been completed. Through appropriate selection of structural parameters, improvement of ferrite material properties, and enhanced integration techniques, the PHC of the Ku-band FPS has been increased to over 500 kW, with an IL of less than 1.3 dB and a maximum differential phase shift (MDPS) of approximately 400°.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-12"},"PeriodicalIF":1.9,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1109/TMAG.2025.3646166
Peng-Cheng Yang;Ji-Zhong Zhao;Meng-Xue Liu;Yu-Lin Guo;Qi Yang;Qian Zhao;Suo Bai;Yan-Li Liu;Zhu-Bai Li
RE2(Fe,Co)14B magnets bear a high Curie temperature, but their coercivity decreases due to the poor crystal structure stability of RE2(Fe,Co)14B. In this article, Al element was added into RE–(Fe,Co)–Al–B magnets, and the coercivity increases monotonously with the addition of Al elements. For Al content of 0.8 at.%, the coercivity increases to 18.6 kOe in RE14(Fe,Co)79.5Al0.8B5.7 magnets, and the remanence does not decrease obviously. Whereas the content of Al is more than 1.2 at.%, the degree of increase in coercivity reduces, and the remanence decreases obviously. There exists the minor phase of RE(Fe,Co)2 phase, RE-rich phase, and RE–oxide in the sintered RE–(Fe,Co)–Al–B magnets. For the high content of Al, the amount of RE(Fe,Co)2 phase increases, and so the remanence obviously decreases. The addition of the Al element leads to an increase in the melt-point of RE2(Fe,Co)14B phase, and the range of phase transition temperature is narrowed, implying the improvement in the structure stability of RE2(Fe,Co)14B crystals. The magnetocrystalline anisotropy decreases a little due to the addition of the Al element, while the coercivity increases, which should be attributed to both the effects of the RE-rich phase and the improvement of crystal structure stability. The thermal stability of remanence in RE–(Fe,Co)–Al–B is much better than that in commercial Nd–Fe–B magnets, and if further improving the coercivity using the grain boundary diffusion, both the remanence and coercivity with high thermal stability are expected to be acquired in RE–(Fe,Co)–Al–B magnets.
RE2(Fe,Co)14B磁体具有较高的居里温度，但由于RE2(Fe,Co)14B晶体结构稳定性差，其矫顽力降低。本文将Al元素添加到RE - (Fe,Co) - Al - b磁体中，其矫顽力随Al元素的加入而单调增加。对于Al含量为0.8 at的。%, RE14(Fe,Co)79.5Al0.8B5.7磁体矫顽力提高到18.6 kOe，剩余物没有明显降低。而Al的含量大于1.2 at。%时矫顽力增加程度减小，剩余物明显减少。烧结后的RE- (Fe,Co) - al - b磁体中存在少量的RE(Fe,Co)2相、富RE相和RE氧化物相。随着Al含量的增加，RE(Fe,Co)2相的数量增加，剩余物明显减少。Al元素的加入提高了RE2(Fe,Co)14B相的熔点，缩小了相变温度范围，提高了RE2(Fe,Co)14B晶体的结构稳定性。Al元素的加入使磁晶各向异性略有降低，而矫顽力则有所提高，这应归因于富re相的作用和晶体结构稳定性的提高。RE - (Fe,Co) - al - b磁体剩余物的热稳定性远好于工业级Nd-Fe-B磁体，如果利用晶界扩散进一步提高矫顽力，有望获得具有高热稳定性的剩余物和矫顽力。
{"title":"Phase Analysis and Magnetic Properties in Sintered RE–(Fe,Co)–Al–B Magnets","authors":"Peng-Cheng Yang;Ji-Zhong Zhao;Meng-Xue Liu;Yu-Lin Guo;Qi Yang;Qian Zhao;Suo Bai;Yan-Li Liu;Zhu-Bai Li","doi":"10.1109/TMAG.2025.3646166","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3646166","url":null,"abstract":"RE2(Fe,Co)14B magnets bear a high Curie temperature, but their coercivity decreases due to the poor crystal structure stability of RE2(Fe,Co)14B. In this article, Al element was added into RE–(Fe,Co)–Al–B magnets, and the coercivity increases monotonously with the addition of Al elements. For Al content of 0.8 at.%, the coercivity increases to 18.6 kOe in RE14(Fe,Co)79.5Al0.8B5.7 magnets, and the remanence does not decrease obviously. Whereas the content of Al is more than 1.2 at.%, the degree of increase in coercivity reduces, and the remanence decreases obviously. There exists the minor phase of RE(Fe,Co)2 phase, RE-rich phase, and RE–oxide in the sintered RE–(Fe,Co)–Al–B magnets. For the high content of Al, the amount of RE(Fe,Co)2 phase increases, and so the remanence obviously decreases. The addition of the Al element leads to an increase in the melt-point of RE2(Fe,Co)14B phase, and the range of phase transition temperature is narrowed, implying the improvement in the structure stability of RE2(Fe,Co)14B crystals. The magnetocrystalline anisotropy decreases a little due to the addition of the Al element, while the coercivity increases, which should be attributed to both the effects of the RE-rich phase and the improvement of crystal structure stability. The thermal stability of remanence in RE–(Fe,Co)–Al–B is much better than that in commercial Nd–Fe–B magnets, and if further improving the coercivity using the grain boundary diffusion, both the remanence and coercivity with high thermal stability are expected to be acquired in RE–(Fe,Co)–Al–B magnets.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-7"},"PeriodicalIF":1.9,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1109/TMAG.2025.3646293
Yu Tang;Barry Gallacher;Zimeng Yu;Sarah Olsen
Galfenol thin films demonstrate significant potential for microelectromechanical system (MEMS) applications due to their notable magnetostrictive properties and favorable mechanical characteristics. In this study, we report an investigation into the modifications in both the amorphous and crystalline structures of galfenol thin films subjected to various direct current (dc) magnetron sputtering parameters, employing atomic force microscopy (AFM), magnetic force microscopy (MFM), and X-ray diffraction (XRD) techniques. Our results indicate that coercivity force increases with higher sputtering power but decreases as the Ar working pressure rises. Furthermore, the effects of film thickness, root mean square (rms) surface roughness, and sputtering parameters on magnetostriction were systematically investigated.
{"title":"Effects of DC Magnetron Sputtering Parameters on the Topography and Magnetic Properties of Galfenol/SiC Films","authors":"Yu Tang;Barry Gallacher;Zimeng Yu;Sarah Olsen","doi":"10.1109/TMAG.2025.3646293","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3646293","url":null,"abstract":"Galfenol thin films demonstrate significant potential for microelectromechanical system (MEMS) applications due to their notable magnetostrictive properties and favorable mechanical characteristics. In this study, we report an investigation into the modifications in both the amorphous and crystalline structures of galfenol thin films subjected to various direct current (dc) magnetron sputtering parameters, employing atomic force microscopy (AFM), magnetic force microscopy (MFM), and X-ray diffraction (XRD) techniques. Our results indicate that coercivity force increases with higher sputtering power but decreases as the Ar working pressure rises. Furthermore, the effects of film thickness, root mean square (rms) surface roughness, and sputtering parameters on magnetostriction were systematically investigated.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-6"},"PeriodicalIF":1.9,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-18DOI: 10.1109/TMAG.2025.3645930
Jelena M. Orelj;Radoslav S. Surla;Vladimir. B. Pavlović;Nebojša S. Mitrović
The magnetoimpedance (MI) element of $mathrm{Co}_{72.5} mathrm{Si}_{12.5} mathrm{~B}_{15}$ amorphous wires, designed for magnetic sensors, was examined in an external axial dc magnetic field (up to $H_{text {max }} approx 15 mathrm{kA} / mathrm{m}$ ) and a frequency range of $1 mathrm{MHz} leq f leq 12 mathrm{MHz}$ . The peak value of the impedance modulus, $Z_{text {max }}$ , of approximately $100 Omega$ , was registered at a frequency of 12 MHz and an external magnetic field of $2.18 mathrm{kA} / mathrm{m}$ . A maximum MI-ratio of 384% was recorded at 1 MHz and a magnetically saturated state. The magnetic anisotropy field $H_k$ exhibits a linear increase in the operating frequency range from 1 to 7 MHz, followed by a further non-linear huge increase. The frequency dependence of the MI-ratio with the magnetic field as a parameter approved a low dc magnetic field sensing.
研究了用于磁传感器的$mathrm{Co}_{72.5} mathrm{Si}_{12.5} mathrm{~B}_{15}$非晶导线的磁阻抗（MI）元件在外部轴向直流磁场（最大$H_{text {max }} approx 15 mathrm{kA} / mathrm{m}$）和频率范围$1 mathrm{MHz} leq f leq 12 mathrm{MHz}$下的性能。阻抗模量的峰值$Z_{text {max }}$约为$100 Omega$，在12 MHz的频率和$2.18 mathrm{kA} / mathrm{m}$的外部磁场下被记录下来。最大MI-ratio为384% was recorded at 1 MHz and a magnetically saturated state. The magnetic anisotropy field $H_k$ exhibits a linear increase in the operating frequency range from 1 to 7 MHz, followed by a further non-linear huge increase. The frequency dependence of the MI-ratio with the magnetic field as a parameter approved a low dc magnetic field sensing.
{"title":"MI-Sensing Properties of CoSiB Amorphous Wires","authors":"Jelena M. Orelj;Radoslav S. Surla;Vladimir. B. Pavlović;Nebojša S. Mitrović","doi":"10.1109/TMAG.2025.3645930","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3645930","url":null,"abstract":"The magnetoimpedance (MI) element of <inline-formula> <tex-math>$mathrm{Co}_{72.5} mathrm{Si}_{12.5} mathrm{~B}_{15}$ </tex-math></inline-formula> amorphous wires, designed for magnetic sensors, was examined in an external axial dc magnetic field (up to <inline-formula> <tex-math>$H_{text {max }} approx 15 mathrm{kA} / mathrm{m}$ </tex-math></inline-formula>) and a frequency range of <inline-formula> <tex-math>$1 mathrm{MHz} leq f leq 12 mathrm{MHz}$ </tex-math></inline-formula>. The peak value of the impedance modulus, <inline-formula> <tex-math>$Z_{text {max }}$ </tex-math></inline-formula>, of approximately <inline-formula> <tex-math>$100 Omega$ </tex-math></inline-formula>, was registered at a frequency of 12 MHz and an external magnetic field of <inline-formula> <tex-math>$2.18 mathrm{kA} / mathrm{m}$ </tex-math></inline-formula>. A maximum MI-ratio of 384% was recorded at 1 MHz and a magnetically saturated state. The magnetic anisotropy field <inline-formula> <tex-math>$H_k$ </tex-math></inline-formula> exhibits a linear increase in the operating frequency range from 1 to 7 MHz, followed by a further non-linear huge increase. The frequency dependence of the MI-ratio with the magnetic field as a parameter approved a low dc magnetic field sensing.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-4"},"PeriodicalIF":1.9,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Magnetic tunnel junctions (MTJs) are of great significance for the next generation ultrafast spintronic memories due to their non-volatility and nanosecond-level writing characteristics. Effective spin manipulation is the key to realizing high-speed field-free magnetic random access memories (MRAMs). In this article, the performance of applying the interlayer Dzyaloshinsky–Moriya interaction (DMI) to the conventional MTJ structure is investigated. By replacing the perpendicular free layer with a composite structure of out-of-plane free layer/coupling layer/in-plane free layer, the rapid switching of MTJs is achieved. We analyze the working conditions of the device through macrospin simulations and verify them by micromagnetic simulations. This structure significantly improves the speed at which the magnetic moment recovers to stability after the removal of external effects (voltage and current), reaching 56.25% of the traditional spin–orbit torque (SOT) MTJ. We believe that our work may promote the research and development of high-speed and field-free MRAMs in the future.
{"title":"Multilayer Field-Free Magnetic Tunnel Junction With Interlayer Dzyaloshinsky–Moriya Interaction","authors":"Rui Zhou;Haiyang Zhang;Jin He;Qijun Huang;Hao Wang;Sheng Chang","doi":"10.1109/TMAG.2025.3645739","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3645739","url":null,"abstract":"Magnetic tunnel junctions (MTJs) are of great significance for the next generation ultrafast spintronic memories due to their non-volatility and nanosecond-level writing characteristics. Effective spin manipulation is the key to realizing high-speed field-free magnetic random access memories (MRAMs). In this article, the performance of applying the interlayer Dzyaloshinsky–Moriya interaction (DMI) to the conventional MTJ structure is investigated. By replacing the perpendicular free layer with a composite structure of out-of-plane free layer/coupling layer/in-plane free layer, the rapid switching of MTJs is achieved. We analyze the working conditions of the device through macrospin simulations and verify them by micromagnetic simulations. This structure significantly improves the speed at which the magnetic moment recovers to stability after the removal of external effects (voltage and current), reaching 56.25% of the traditional spin–orbit torque (SOT) MTJ. We believe that our work may promote the research and development of high-speed and field-free MRAMs in the future.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-6"},"PeriodicalIF":1.9,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article presents a modified analytical method for evaluating the apparent power in homogenized models of conductor arrays, with particular focus on structures exhibiting periodic and regular hexagonal symmetry. For analyzing the external effect, the extended Ollendorff formula is implemented. For evaluating the internal effect, by solving the diffusion equation with Bessel functions, the apparent power inside the conductor is obtained using the Poynting theorem. The total power of the unit cell is subsequently completed through the application of Ampère’s circuital law. The accuracy of the modified analytical solution is validated against detailed finite element simulations across a wide frequency range. Results show that the modified method significantly improves the prediction of reactive power, especially in the high-frequency regime, while maintaining excellent accuracy in active power estimation. The effectiveness of the method is further demonstrated in large-scale, homogenized domains composed of multiple periodic and hexagonal cells. Detailed field distribution comparisons confirm the validity of the homogenization process.
{"title":"Modified Semianalytical Approach for Homogenization on Multicoils","authors":"Shuli Yin;Junkai Tian;Zhijiang Liang;Youpeng Huangfu;Xikui Ma;Hajime Igarashi","doi":"10.1109/TMAG.2025.3645791","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3645791","url":null,"abstract":"This article presents a modified analytical method for evaluating the apparent power in homogenized models of conductor arrays, with particular focus on structures exhibiting periodic and regular hexagonal symmetry. For analyzing the external effect, the extended Ollendorff formula is implemented. For evaluating the internal effect, by solving the diffusion equation with Bessel functions, the apparent power inside the conductor is obtained using the Poynting theorem. The total power of the unit cell is subsequently completed through the application of Ampère’s circuital law. The accuracy of the modified analytical solution is validated against detailed finite element simulations across a wide frequency range. Results show that the modified method significantly improves the prediction of reactive power, especially in the high-frequency regime, while maintaining excellent accuracy in active power estimation. The effectiveness of the method is further demonstrated in large-scale, homogenized domains composed of multiple periodic and hexagonal cells. Detailed field distribution comparisons confirm the validity of the homogenization process.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-9"},"PeriodicalIF":1.9,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1109/TMAG.2025.3644349
Junfeng Gao;Xinhua Wang;Tao Sun;Zisheng Guo;Lin Yang;Amjad Ali;Yuxia Han
To overcome the limitations of conventional non-destructive testing (NDT) methods for pipelines operating under extreme conditions, such as high temperatures and cryogenic environments, a novel differential magnetic field coil sensor has been designed. This sensor reduces interference from the excitation magnetic field on detection signals, thereby improving the signal-to-noise ratio (SNR). This coil sensor employs harmonic magnetic field excitation (HMFE), utilizing a high-sensitivity pickup coil to receive magnetic field signals. The HMFE technique effectively enhances magnetic field penetration depth by modulating the pipeline's magnetic permeability. Both finite element simulations and experiments demonstrate that HMFE improves the distribution of induced currents within the pipe body, increasing detection depth and accuracy. The proposed differential magnetic field coil sensor enables non-contact inspection of insulated pipelines. Under HMFE, the detection signal contains rich defect characteristic signals. It can effectively detect typical pipeline defects beneath 100 mm thick insulation layers, capable of identifying corrosion pits as small as 3 cm2 at a depth of 2 mm and through-holes with diameters as small as 10 mm. It also demonstrates excellent detection performance for circumferential scratches on pipelines. Even when defects are oriented at a 45° angle relative to the inspection position, the method maintains reliable identification capabilities.
{"title":"A New Sensor for Harmonic Magnetic Field Detection in Pipelines Without Removing Insulation Layer","authors":"Junfeng Gao;Xinhua Wang;Tao Sun;Zisheng Guo;Lin Yang;Amjad Ali;Yuxia Han","doi":"10.1109/TMAG.2025.3644349","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3644349","url":null,"abstract":"To overcome the limitations of conventional non-destructive testing (NDT) methods for pipelines operating under extreme conditions, such as high temperatures and cryogenic environments, a novel differential magnetic field coil sensor has been designed. This sensor reduces interference from the excitation magnetic field on detection signals, thereby improving the signal-to-noise ratio (SNR). This coil sensor employs harmonic magnetic field excitation (HMFE), utilizing a high-sensitivity pickup coil to receive magnetic field signals. The HMFE technique effectively enhances magnetic field penetration depth by modulating the pipeline's magnetic permeability. Both finite element simulations and experiments demonstrate that HMFE improves the distribution of induced currents within the pipe body, increasing detection depth and accuracy. The proposed differential magnetic field coil sensor enables non-contact inspection of insulated pipelines. Under HMFE, the detection signal contains rich defect characteristic signals. It can effectively detect typical pipeline defects beneath 100 mm thick insulation layers, capable of identifying corrosion pits as small as 3 cm2 at a depth of 2 mm and through-holes with diameters as small as 10 mm. It also demonstrates excellent detection performance for circumferential scratches on pipelines. Even when defects are oriented at a 45° angle relative to the inspection position, the method maintains reliable identification capabilities.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-11"},"PeriodicalIF":1.9,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1109/TMAG.2025.3644394
Linhai Hu;Yun Xu;Haoran Lv;Chenyu Zhao
Multi-target transcranial magnetic stimulation (TMS) overcomes the limitations of single-coil physical movement by enabling collaborative stimulation with multiple coils, which has become a key trend in neural modulation research. However, however, current regulation and synchronization challenges arising from multi-coil coupling remain unresolved. This article takes a three-coil coupled system as the research object and proposes a complete solution from underlying modeling to experimental verification: using Kirchhoff’s laws, transient expressions for capacitor voltage and coil current under coupling are derived, a circuit-electromagnetic field coupled model is established, and an accurate expression of the current waveform is provided. This approach determines the capacitance values and precise voltages for different modes and achieves improved synchronization of coil current waveforms by combining capacitor switching and voltage regulation. Circuit simulation verification using Simulink shows that the cosine similarity of current synchronization reaches over 0.9. Further verification is conducted through circuit experiments, and the magnetic field distribution driven by current waveforms is simulated in COMSOL, successfully achieving effective stimulation with electric field strength greater than 100 V/m and mode switching under Mode 1 (1.3 cm shallow double targets) and Mode 2 (2.2 cm deep single target). The research indicates that precise control based on circuit-coupled modeling can effectively enhance the current synchronization of multi-coil coupled system, providing a theoretical basis and engineering practice paradigm for the clinical application of multi-target switching TMS.
{"title":"A Multi-Target Transcranial Magnetic Stimulation System With Coupled Modeling Control","authors":"Linhai Hu;Yun Xu;Haoran Lv;Chenyu Zhao","doi":"10.1109/TMAG.2025.3644394","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3644394","url":null,"abstract":"Multi-target transcranial magnetic stimulation (TMS) overcomes the limitations of single-coil physical movement by enabling collaborative stimulation with multiple coils, which has become a key trend in neural modulation research. However, however, current regulation and synchronization challenges arising from multi-coil coupling remain unresolved. This article takes a three-coil coupled system as the research object and proposes a complete solution from underlying modeling to experimental verification: using Kirchhoff’s laws, transient expressions for capacitor voltage and coil current under coupling are derived, a circuit-electromagnetic field coupled model is established, and an accurate expression of the current waveform is provided. This approach determines the capacitance values and precise voltages for different modes and achieves improved synchronization of coil current waveforms by combining capacitor switching and voltage regulation. Circuit simulation verification using Simulink shows that the cosine similarity of current synchronization reaches over 0.9. Further verification is conducted through circuit experiments, and the magnetic field distribution driven by current waveforms is simulated in COMSOL, successfully achieving effective stimulation with electric field strength greater than 100 V/m and mode switching under Mode 1 (1.3 cm shallow double targets) and Mode 2 (2.2 cm deep single target). The research indicates that precise control based on circuit-coupled modeling can effectively enhance the current synchronization of multi-coil coupled system, providing a theoretical basis and engineering practice paradigm for the clinical application of multi-target switching TMS.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-6"},"PeriodicalIF":1.9,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article presents a degradation model that characterizes the local magnetization properties of non-oriented electrical steel, which takes into account the effects of wire electrical discharge machining (WEDM) and stress relief annealing. The innovation of the presented model lies in its minimal requirement of the measured sample data and the capability of predicting the magnetization properties of narrow structures where degraded areas overlap. In particular, only a single test sample along with original material data is needed to obtain the model coefficients for non-annealed steel sheets. Such a low demand for the measured source data is attributed to the accurate model setup, combined with the residual stress and the limited number of model coefficients. The presented model is fit and applied to the test samples, which are cut from three grades of steel sheets using the WEDM method, both with and without the annealing process. To validate the effectiveness of the proposed model and assess the manufacturing impact on real motors, two synchronous reluctance machines are fabricated with WEDM and annealing methods and measured. Compared to the calculated results using original material data, the static torque calculation error is reduced from 6.9% and 5.6% to 0.8% and 1.4% with the proposed material degradation model.
{"title":"Degradation Model on B–H Curves of Non-Oriented Electrical Steel Considering Wire Electrical Discharge Machining and Annealing","authors":"Youhao Zhang;Kejia Zhang;Dan Shi;Yunchong Wang;Shun Cai;Wenzhi Chen;Jian-Xin Shen","doi":"10.1109/TMAG.2025.3642539","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3642539","url":null,"abstract":"This article presents a degradation model that characterizes the local magnetization properties of non-oriented electrical steel, which takes into account the effects of wire electrical discharge machining (WEDM) and stress relief annealing. The innovation of the presented model lies in its minimal requirement of the measured sample data and the capability of predicting the magnetization properties of narrow structures where degraded areas overlap. In particular, only a single test sample along with original material data is needed to obtain the model coefficients for non-annealed steel sheets. Such a low demand for the measured source data is attributed to the accurate model setup, combined with the residual stress and the limited number of model coefficients. The presented model is fit and applied to the test samples, which are cut from three grades of steel sheets using the WEDM method, both with and without the annealing process. To validate the effectiveness of the proposed model and assess the manufacturing impact on real motors, two synchronous reluctance machines are fabricated with WEDM and annealing methods and measured. Compared to the calculated results using original material data, the static torque calculation error is reduced from 6.9% and 5.6% to 0.8% and 1.4% with the proposed material degradation model.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-10"},"PeriodicalIF":1.9,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-05DOI: 10.1109/TMAG.2025.3640967
Jéssica Kamilly Pereira França;Aline Alves de Freitas;Hellen Barros Lopes Silva;Maurício Silva Lopes;Hudson Antonio Dias Teixeira;Walajhone Oliveira Pereira;Alan Silva de Menezes;Adenilson Oliveira Dos Santos;Luzeli Moreira da Silva
Multiphase alloys with sequential long-range magnetic order represent an intriguing approach to overcoming an intrinsic limitation of single-phase magnetocaloric materials by broadening the operational temperature window and enhancing thermal coupling between phases. In this study, we investigate a dysprosium–platinum–indium (Dy–Pt–In) alloy with a nominal composition of 35 wt% Dy, 41 wt% Pt, and 24 wt% In, synthesized by arc melting and characterized in terms of its structural, microstructural, magnetic, and magnetocaloric properties. Rietveld refinement of X-ray diffraction data, combined with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses, revealed a multiphase alloy composed of a DyPtIn, DyPt2In, and dysprosium–platinum (DyPt) intermetallic phases. The alloy exhibit three magnetic transitions: two successive ferromagnetic (FM) transitions at 32.5 and 23.0 K, and a field-dependent antiferromagnetic-like transition at 7.5 K, which together sustain an nearly constant adiabatic temperature change of ~2.1 K across a broad temperature range (2.5–57 K) and a maximum magnetic entropy change of ~6.3 J/kg·K for a field variation of 50 kOe. The results demonstrate the potential of Dy–Pt–In multiphase systems to extend the working temperature span and enhance the performance of cryogenic magnetic refrigeration (MR) applications.
{"title":"Magnetic Properties and Magnetocaloric Performance in a Dy–Pt–In Multiphase Alloy","authors":"Jéssica Kamilly Pereira França;Aline Alves de Freitas;Hellen Barros Lopes Silva;Maurício Silva Lopes;Hudson Antonio Dias Teixeira;Walajhone Oliveira Pereira;Alan Silva de Menezes;Adenilson Oliveira Dos Santos;Luzeli Moreira da Silva","doi":"10.1109/TMAG.2025.3640967","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3640967","url":null,"abstract":"Multiphase alloys with sequential long-range magnetic order represent an intriguing approach to overcoming an intrinsic limitation of single-phase magnetocaloric materials by broadening the operational temperature window and enhancing thermal coupling between phases. In this study, we investigate a dysprosium–platinum–indium (Dy–Pt–In) alloy with a nominal composition of 35 wt% Dy, 41 wt% Pt, and 24 wt% In, synthesized by arc melting and characterized in terms of its structural, microstructural, magnetic, and magnetocaloric properties. Rietveld refinement of X-ray diffraction data, combined with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses, revealed a multiphase alloy composed of a DyPtIn, DyPt2In, and dysprosium–platinum (DyPt) intermetallic phases. The alloy exhibit three magnetic transitions: two successive ferromagnetic (FM) transitions at 32.5 and 23.0 K, and a field-dependent antiferromagnetic-like transition at 7.5 K, which together sustain an nearly constant adiabatic temperature change of ~2.1 K across a broad temperature range (2.5–57 K) and a maximum magnetic entropy change of ~6.3 J/kg·K for a field variation of 50 kOe. The results demonstrate the potential of Dy–Pt–In multiphase systems to extend the working temperature span and enhance the performance of cryogenic magnetic refrigeration (MR) applications.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 1","pages":"1-9"},"PeriodicalIF":1.9,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11278829","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145847823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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