Magnetic Coil Research Articles

Repetitive transcranial magnetic stimulation as a modality of treatment in patients with fibromyalgia

BackgroundFibromyalgia is characterized by widespread musculoskeletal pain and tenderness. It is also frequently associated with mood disorders, tiredness, sleep disturbances, and cognitive dysfunction. Repetitive transcranial magnetic stimulation (rTMS) is an emerging nonpharmacological therapeutic option for fibromyalgia. rTMS involves an electromagnetic coil placed on the scalp that is rapidly turned on and off to generate short magnetic pulses to the brain (2).rTMS can reduce chronic pain by triggering inhibitory neural pathways at the level of the dorsal horn of the spinal cord. It can improve motor function and alleviate psychiatric symptoms, including depression and anxiety, in many diseases (7).Aim of the workThe study aimed to evaluate the role of repetitive transcranial magnetic stimulation (rTMS) in treating fibromyalgia.ResultsHighly significant improvement in feel-good and work-missed scores by FIQ being lower in the case group compared to the control group (p-values 0.008 and 0.003 respectively). On comparing the control and case groups regarding anxiety and depression using the HADS questionnaire and fatigue assessment using the SF36 questionnaire after rTMS sessions, there was a statistically significant lower depression score in the case group compared to the control group (p-value of 0.024), and statistically significant higher energy/fatigue scores in the case group compared to the control group with (p-value = 0.004).ConclusionThis study demonstrated that rTMS relieved pain, reduced anxiety, depression, and fatigue and enhanced quality of life in patients with fibromyalgia.

A novel multifrequency-tuned transceiver array for human-brain 31P-MRSI at 7 T.

Phosphorus-31 (31P) MR spectroscopy imaging (MRSI) at 7 T is a powerful tool for investigating high-energy phosphate metabolism in human brains with significantly improved signal-to-noise ratio (SNR) and spectral resolution. However, this imaging technique requires dual-frequency radiofrequency coil for performing brain anatomical imaging and B0 shimming at proton (1H) operation frequency, and 31P MRSI at lower operation frequency. Herein, we introduce a novel 31P-1H dual-frequency radiofrequency coil design using a double-tuned and double-matched (DODO) coil that does not require complex circuitry or two coil layers and exhibits similar imaging performance as to single-frequency control coils for both 31P and 1H imaging operations. We constructed an eight-element 31P-1H dual-frequency DODO transceiver array and compared its performance with a quadrature-driven dual-tuned eight-element 31P and eight-element 1H transverse electromagnetic volume coil for both phantom and in vivo human-brain 31P-MRSI studies at 7 T. The DODO transceiver array achieved high spatiotemporal resolution 31P MRSI with 2.5-cc nominal voxel size and 22-min scan time covering the entire human brain, showing excellent SNR for mapping cerebral phosphorous metabolites such as phosphocreatine, adenosine triphosphate, and other low-concentration metabolites. Compared with the transverse electromagnetic volume coil, the DODO array demonstrated large improvements in 31P-MRSI SNR in both phantom and human brain studies, with over 5-fold SNR gain in peripheral regions and over 2-fold SNR gain in central brain regions. This simple and cost-effective array design and excellent performance can greatly benefit human-brain 31P-MRSI applications at 7 T.

Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section

Efficient calculation of self magnetic field, self-force, and self-inductance for electromagnetic coils with rectangular cross-section

Stellarator fusion systems enabled by arrays of planar coils

Abstract We present an overview of a novel electromagnetic coil configuration for stellarators and its application to two near-term fusion systems. The novel coil configuration is the planar coil stellarator, able to implement precisely-quasisymmetric 3D magnetic fields using a set of planar, plasma-encircling coils and a set of planar, field-shaping coils situated on a surface surrounding the plasma. This configuration combines the stellarator’s advantages of steady-state operation, stability, low recirculating power fraction, and a mature physics basis, with the benefits of using simpler, planar coils which allow for a maintenance scheme leveraging large ports, and the ability to control magnets individually. The initial near-term use case considered is a steady state deuterium–deuterium stellarator neutron source, called Eos. The second near-term use case considered is a deuterium–tritium stellarator fusion pilot plant, called Helios, that would be approximately twice the linear dimension of the Eos design.

Electromagnetic Railguns and Coil Guns: Comprehensive Analysis of Physical Principles and Applications and Experimental Improvements

This research is mainly to provides a report and summary of the production and experimental principle of our last electromagnetic gun Electromagnetic guns use the basic principle in physics that moving charges or current-carrying conductors are subjected to the electromagnetic force (i.e., the Lorentz force) in a magnetic field to accelerate projectiles. According to the acceleration method, electromagnetic guns can be divided into rail guns and coil guns . An electromagnetic railgun accelerates projectiles using the fundamental principles of physics involving moving charges and current-carrying conductors interacting with a magnetic field, known as the Lorentz force. Electromagnetic Railguns accelerate projectiles to very high speeds using Lorentz force generated by strong electric pulses through parallel conductive rails . A coilgun is a device that uses electromagnetic fields to accelerate metallic projectiles. Its working principle is based on Faraday's law of electromagnetic induction. By passing current through a coil, a strong magnetic field is generated, which propels the projectile along the guide rail. Coilguns offer several advantages over traditional gunpowder-based propulsion methods, including higher initial velocities, extended ranges, reduced recoil, and lower launch noise. However, despite these potential benefits, our experimental setup revealed several limitations.This report summarizes the challenges encountered and Outlines suggested strategies for improving the design and addressing the identified deficiencies, analyzing the problem through a qualitative perspective. To provide readers with effective information

Energy-Efficient Dual-Site Transcranial Magnetic Stimulation System With Optimized Magnetic Coils

Energy-Efficient Dual-Site Transcranial Magnetic Stimulation System With Optimized Magnetic Coils

Optimization of the Toroidal Magnetic Coil System for the Small Spherical Tokamak MEPhIST-0

A novel design of a continuous toroidal solenoid for the small spherical tokamak MEPhIST-0 is presented. The solenoid’s geometry is optimized in regard to stray magnetic fields perpendicular to the toroidal fields based on Maxwell’s equations and interface conditions for magnetic fields. The solutions obtained may in theory provide the level of stray fields ~10−10 of the toroidal fields. The design of the solenoid is tested by means of COMSOL modeling. The observed ratio of stray fields to the toroidal component of magnetic fields, Bp/BT is approximately ~0.4% at the plasma center. A ripple of the toroidal magnetic field at the edge of the plasma of δ ~ 0.8% is observed. The possibility of plasma breakdown with the chosen toroidal solenoid configuration was evaluated using the DINA calculation code.

Design of high uniformity magnetic field coils for magnetoencephalography measurement

Design of high uniformity magnetic field coils for magnetoencephalography measurement

Locomoting non-magnetic marbles through meniscus emerged on the water surface using a magnetically actuated ferrofluid marble under pulsating and steady magnetic fields.

Recent progress in digital microfluidics has revealed the distinct advantages of liquid marbles, such as minimal surface friction, reduced evaporation rates, and non-wettability compared to uncoated droplets. This study provides a comprehensive examination of an innovative technique for the precise, contamination-free manipulation of non-magnetic water liquid marbles (WLMs) carried by a ferrofluid liquid marble (FLM) under the control of direct current (DC) and pulse-width modulation (PWM) magnetic fields. The concept relies on the phenomenon in which an FLM and WLMs form a shared meniscus when placed together on a water surface, causing the WLMs to closely track the magnetically actuated FLM. The study also explores the dynamic behavior of the marbles by assessing several influencing parameters: magnetic coil current, the starting position of the marbles from the coil, the number of WLMs carried by the FLM, the volume ratio between the WLM and FLM, and the PWM magnetic field properties, including duty cycle and frequency. The results demonstrate that increasing the magnetic coil current or reducing the volume ratio decreases the travel time and enhances the velocity of the carrier FLM under both DC and PWM magnetic fields. Notably, the FLM exhibits significant capability to transport multiple WLMs, although its average and maximum velocity decrease with each additional WLM. Moreover, the travel time of the marbles varies proportionally with the PWM frequency while exhibiting an inverse relationship with the duty cycle.

Mechanical Design of a Common Coil Magnet with RMC Coils (ISAAC)

Mechanical Design of a Common Coil Magnet with RMC Coils (ISAAC)

Multipole Multi-Layered Magnetorheological Brake with Intermediate Slots

Magnetorheological (MR) brakes are flourishing in low-torque applications due to their dynamic controllability nature. Researchers have introduced multi-layer and multipole concepts to increase the torque–volume ratio (TVR) of the MR brake. However, the combination of these two ideas did not exist due to the design limitations. Therefore, this study aims to design a brake that combines the multipole magnetic field and multi-layered structure concepts. The axial slots were introduced on the brake rotor and the stator drum axial surfaces to achieve a high TVR. These slots stop the flux bypass in the inner layers; therefore, the magnetic flux can also reach the brake’s outer layers. This brake was designed with multiple stator and rotor drums and MR fluid layers. The number of poles was placed so that the magnetic field from these poles traveled in a closed loop via the stator, rotor, and MR layers. A 3D model of the brake was prepared for the virtual study. Electromagnetic simulations were conducted to analyze the effect of axial slots’ and other design parameters of the brake. According to those simulation results, the axial slots’ width and position significantly affect the brake output torque. The maximum torque obtained from the brake is 38 Nm, and the TVR value of the brake is 41 Nm/dm3. Additionally, multiphysics simulations were performed to understand the Joule-heating effect of the magnetic coil and the frictional heating in MR fluid. Results showed that the maximum possible temperature in the brake is under the MR fluid temperature limits. Therefore, this multipole multi-layered (MPML) MR brake with axial slots idea is very useful for high-torque MR brake growth.

A Force-Thermal-Magnetic Trimodal Flexible Sensor for Ultrafine Recognition of Metallic Materials.

Humans possess the remarkable ability to perceive the intricate world by integrating multiple senses. However, the challenge of enabling humanoid robots to achieve multimodal sensing and fine recognition of metallic materials persists. In this study, we propose a flexible tactile sensor that mimics the sensory patterns of human skin, which is assembled by a flexible electromagnetic coil that is engraved on the surface of a polyimide substrate and porous MXene/CNT aerogel. This sensor is capable of detecting pressure, temperature, and inductive signals with minimal interference via three disparate response mechanisms of the piezoresistive sensing, the thermoelectric principle, and the electromagnetic induction effect, allowing the device with the abilities of sensing grasp forces and selectively identifying ferromagnetic and nonferromagnetic metals, which has a high accuracy rate of 99.2% in distinguishing mixed metals with varying ratios based on the fusion algorithm of multimodal sensory data. Further, the sensor was integrated on a humanoid robotic hand to demonstrate its recognition capacity of objects used in a kitchen setting and a simulated scenario of mineral exploration, achieving a remarkable ultrafine accuracy of 100% in distinguishing 16 common metal products. These findings will pave the way for humanoid robots to attain heightened levels of perception and recognition.

A foreign object detection method based on a laminated coil for wireless power transfer

Foreign objects in magnetically coupled resonant wireless power transfer (MCR-WPT) systems cause eddy effects, reducing efficiency and raising the temperature. To address this, a high-frequency multilayer detection coil and composite topology circuit are designed to enhance sensitivity by dynamically adjusting component parameters. Verified through Maxwell simulation, the proposed method improves detection efficiency by 46% and eliminates blind spots compared to square coils. The detection range expands by 66% with a 3 × 3 reverse series-laminated coil, effectively decoupling sub-coils and broadening coverage. Experimental results show accurate detection of various foreign objects, such as iron and copper, by analyzing changes in magnetic fields and detection coil voltage. This approach enhances MCR-WPT system safety and efficiency, making it suitable for complex environments.

Experimental investigation of the radial structure of energetic particle driven GAM in TCV

Abstract High amplitude energetic particle geodesic acoustic mode (EGAM) oscillations driven by Neutral Beam (NBI) injected in the direction counter to the toroidal plasma current are observed in the TCV tokamak. The modes appear at frequencies close to the geodesic acoustic mode (GAM) frequency, corresponding to the mode radii calculated without plasma elongation corrections. The spatial structure of the EGAM density oscillation is analyzed using multichannel soft x-ray (SXR) and broadband light emission diagnostics. The analysis of spatiotemporal emission data shows a non-rotating structure of the density oscillations. The non-rotating mode discrimination is the additional new capability of the multichannel spatiotemporal SXR data analysis technique in TCV. We present the discrimination method of assessing the standing character of the EGAM wave. The structure of EGAM density oscillations in TCV is consistent with the theoretical GAM poloidal structure, namely a m= 1 standing wave with density oscillations amplitude proportional to sin(θ), where the poloidal angle θ is measured from the equatorial plane. The poloidal structure of magnetic the field oscillations is analyzed using a poloidal array of magnetic coils. The structure of the EGAM-induced magnetic field oscillations in TCV is a m = 2 standing wave. Time evolution of EGAMs suggests that a nonlinear EGAM chirping is observed. The chirping depends on the EGAM radial location, which varies as the NBI deposition is varied through a vertical shift of the plasma magnetic axis. The chirping disappears at the plasma periphery. A fast periodic radial shift of the EGAMs radial location is also observed to occur during the single chirp.

High-security physical layer encryption scheme for dual-mode index modulation-aided OFDM in magnetic induction communication.

A high security physical layer encryption scheme for dual-mode orthogonal frequency division multiplexing with index modulation (DM-OFDM-IM) in magnetic induction communication is proposed. The scheme utilizes DM-OFDM-IM, where subcarriers within each subblock are divided into two groups, each modulated by distinct signal constellations. DM-OFDM-IM leverages the sequential information from the modulated constellation to transmit extra information, leading to a substantial enhancement in spectral efficiency. In order to improve the security of DM-OFDM-IM magnetic communication system, a 4D hyperchaos model is used to generate four columns of chaotic sequences for specific encryption, frequencies, and symbols scrambling of transmitted data to prevent attacks from illegal receivers. A DM-OFDM-IM magnetic communication signal encrypted by 23.76 kb/s is experimentally transmitted on a 36 cm magnetic induction coil. Due to the use of geometric shaping, the communication distance is increased by 0.316 cm compared with the traditional 8QAM modulation at the hard-decision FEC BER limit of 3.8 × 10-3. The experimental results show that the bit error rate (BER) performance of the signal before and after encryption does not significantly differ. In addition, the key space of the scheme can reach 10146, which effectively ensures the physical layer security of the system. This approach offers robust performance and enhanced security, making it a promising solution for short-distance magnetic communication applications.

Vacuum vessel design with lofted toroidal surfaces for a QHS configuration

A vacuum vessel in between the hot plasma and the magnetic coils is crucial for a fusion reactor. In this work, a tool is presented to perform the initial design of such a vessel automatically. Starting from the last closed flux surface, an algorithm is developed which lofts this manifold out as much as possible. At the same time, the algorithm makes sure that no intersection with the coils takes place. In the presented work, this algorithm is applied to the HSX stellarator and it has been verified that the resulting vessel wall can be built from an engineering perspective. Using field line tracing, the strikepoints on the vessel wall indicate the initial locations for a divertor.

Fabrication and characterization of lead lanthanum zirconate titanate ceramic-based fully transparent piezoelectric loudspeakers for next-generation electronic devices

Transparency is a critical attribute of next-generation electronic devices; this ensures unobstructed visibility while maintaining device functionality. Traditional electromagnetic coils are opaque, and piezoelectric materials with high optical transparency, low power consumption, and rapid responses are required when preparing innovative transparent electronics. In this study, we developed lead lanthanum zirconate titanate (PLZT) ceramics with excellent transparency (PLZT S1 = 65 %, PLZT S2 = 42 % at 550 nm) and piezoelectric properties (PLZT S1 = 180 pC/N, PLZT S2 = 470 pC/N). An indium tin oxide (ITO)-coated PLZT ceramic (PLZT S2) was used to create a fully transparent transducer with a glass diaphragm. This delivered outstanding sound output, attaining 105 dB at the resonance frequency (5.6 kHz) at an input of only 5 Vpp. To demonstrate the versatility of PLZT in terms of transparent electronic applications, PLZT transducers were placed on a desiccator wall; this showcased their capacity to emit a warning sound without compromising visibility when gas leaked inside the desiccator. An ITO-coated PLZT disc was employed to fabricate a loudspeaker with a polyethylene terephthalate (PET) diaphragm; this produced sounds from 30 dB to 68 dB across the entire voice frequency spectrum (500 Hz–8 kHz) with an input of 10 Vpp. This loudspeaker meets the demands of next-generation transparent electronics; optical visibility and high-quality sound reproduction are assured without any compromise in terms of sound quality or visual transparency.

The Influence of Magnetic Fields on the Operational State and Velocity of Smart Projectiles

Abstract The electromagnetic railgun, as a novel launching technology, held great potential for development. However, due to the strong magnetic interference during the launch process, most of the electromagnetic railguns that were being researched at that time could only launch kinetic projectiles. By incorporating magnetic shielding materials within the projectile to mitigate the impact of external magnetic fields on the internal circuitry, it became feasible to launch guided missiles and range-determining projectiles. This advancement could have significantly enhanced the versatility of electromagnetic railguns. The paper established a multi-physical field coupling model between the projectile and the magnetic field using the COMSOL software. First, the shielding efficiency of the shielding body inside the projectile as it passed through a uniform magnetic field was calculated. At the same time, when the projectile moved in the magnetic field, it was subjected to an action force exerted by the magnetic field. The paper studied the force relationship between the projectile and the magnetic field and the deceleration of the projectile, and found that the magnetic field had a role of accelerating the projectile first and then decelerating it. The acceleration stage was much smaller than the deceleration stage. The projectile also generated eddy currents in the magnetic field, causing the temperature of the projectile to rise. The experimental results obtained were basically consistent with the numerical calculation results. Under the shielding effect, the internal circuits of the projectile were greatly reduced by the interference of the magnetic field, and the speed and temperature of the projectile remained within a reasonable range. This also provided certain reference for the design of electromagnetic coil gun muzzle velocity measurement devices and proximity fuse signal transmission devices.

Dynamical behavior of a vertical magnetic pendulum driven by one coil magnet excited by a voltage source

Dynamical behavior of a vertical magnetic pendulum driven by one coil magnet excited by a voltage source

Theoretical modeling and analysis of the launching process in an electromagnetic coil launcher

The rapid increase of space activities has led to an urgent problem of space debris. Active debris removal based on flexible nets is promising in the control of space debris. Here the application of electromagnetic launch in the deployment of flexible net is considered. A lumped-parameter electromechanical model of the coil launcher is developed with emphasis on the analysis of the magnetic field involved. Analytical solution to the magnetostaic problem is given based on eigen-expansions on decomposed domains. Dynamic behavior of the iron slug is then computed and analyzed with optimal initial position of the iron slug found. Influence of the capacitance of the super-capacitor upon the launch performance is also investigated. Results are discussed and future directions of investigations are provided.