Magnetic Coil Research Articles

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.

A novel bulk magnetostrictive sensor for bending applications

In this paper, a bulk magnetostrictive material is used to measure bending forces. It is made of a cylindrical vanadium permendur alloy. In this sensor, two comb shape magnetic cores and excitation coils are used to create magnetic fields in the material’s surface layer. When bending force is applied to the material, created stresses causes a change in the magnetic flux density on the surface of the material. Induced voltage changes in the pickup coils are used as the output of the sensor. The range of the sensor is up to 280 Newtons. The accuracy of the bending sensor is ±5.1%FS. The bending force measurement sensitivity of the sensor is 7.5mV/N. By performing combined loading tests, it was found that the sensor is able to detect bending force in both directions. The outputs of the two directions are decoupled and only 4.7 % is affected by each other.

Open-window MSR Design with Active Magnetic Compensation Coil based on COMSOL Multiphysics.

Magnetic shielding room (MSR) is one of the necessary equipment for measuring magnetocardiography (MCG) and magnetoencephalography (MEG). The traditional closed MSR only focuses on the indicators of the shielded magnetic field, and ignores the patient's feelings within the MSR. In this paper, an open-window MSR is proposed to solve the problem that patients have difficulty in communicating with the outside of closed MSR and have closed fear. The simulation results show that the size and distribution trend of the residual magnetic field in the inner working area of the MSR with shield-duct and active magnetic compensation coil is similar to that of the closed MSR. The method proposed in this paper provides a way to improve the comfort of patients in MSR for measuring MCG and MEG in humans.

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.

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.

Research and Analysis of Carbon Fiber-Reinforced Polymer Prepreg Detection Based on Electromagnetic Coil Sensors

Research and Analysis of Carbon Fiber-Reinforced Polymer Prepreg Detection Based on Electromagnetic Coil Sensors

Behavior of plasma parameters under mirror and cusp magnetic fields in DC glow discharge – a numerical study

Abstract The plasma parameters in DC glow discharge can easily be controlled by externally applied magnetic field without disturbing internal / built-in process parameters. Though several works have been carried out to study the influence of the magnetic field at different configurations on the plasma parameters, a complete understanding on the behaviour of the plasma discharge under the mirror and cusp fields could not be achieved. Further studies on the same are needed to improve the efficiency of the DC glow discharge system for existing applications and to find the new applications. In this work, a 2D axis-symmetric non-equilibrium plasma model with drift-diffusion approach is developed to study the characteristics of the plasma in DC glow discharge through various plasma parameters under mirror and cusp fields. The effects of current and position of magnetic coils on electric potential, ionization rate, electron temperature and electron number density are predicted and discussed. The distribution of electron number density at various coil currents and positions under both mirror and cusp fields are presented and the operating conditions favorable for applications in surface modification are suggested.

Structural design and test of superconducting magnet coil for the cooling storage ring external-target experiment

Abstract Heavy ion collision is an unique method for studying cold and dense nuclear matter in labs. The Cooling Storage Ring (CSR) External-target Experiment (CEE) at the Heavy Ion Research Facility in Lanzhou (HIRFL), China, is the first multi-purpose nuclear physics experimental device to operate in the GeV energy range. One of the key parts is a large acceptance dipole magnet, which is used to bend particles so that they can be detected by various detectors. A superconducting coil with the size of 3.1 m ×3.6 m × 2 m was designed to verify the rationality of the scheme. Although the coil-dominated superconducting magnet with NbTi has been used to reduce the weight and size of the magnet, large deformation and stress will occur in the cooldown and excitation stages owing to the large volume and weight. Therefore, it is crucial to design a reasonable structure to ensure the strength of the magnet and prevent the magnet from interfering with other components due to large deformation, and even the possibility of quenching. A truss supporter is proposed for the support of the superconducting coil. In this study, the structural design of the cold mass of a superconducting magnet is introduced, and its mechanical behaviors during cooldown and excitation are analyzed in detail. To verify the feasibility of the coil design and process route, a sub-size prototype was manufactured and tested at 4.2 K and reached the design current successfully.

Design and Optimization of Electromagnetically Driven End-Effector

The excellent flexibility and plasticity of a flexible robotic hand enable it to grip objects of various shapes and sizes. Currently, most of the flexible robotic hand fingers on the market use pneumatic drives. However, the unstable power of the pneumatic drive can cause the object gripped by the finger to slip. Additionally, the pneumatic pump can create noise pollution. To address these issues, a flexible end-effector is designed using an electromagnetic coil as the power source. The electromagnetic-driven end-effector has high precision and fast response, without the need for external devices. It only requires controlling the current to control the magnetic force of the electromagnet, thereby controlling the degree of end-effector bending. The finite element simulation is used to analyze the impact of the structural parameters of the end-effector on bending degree. And the optimal basic parameters of the end-effector are determined. Under the same intensity of the current, when the bottom layer thickness is 5 mm, end-effector knuckle spacing is 4 mm, the maximum angle of end-effector bending is reached.

Wall-Eyed Internuclear Ophthalmoplegia: History and Hypothesis.

Most patients with internuclear ophthalmoplegia (INO) are orthotropic, although a subset is exotropic. When INO is bilateral, this is termed wall-eyed bilateral internuclear ophthalmoplegia (WEBINO). In 1979, Sharpe described his "first case" of wall-eyed monocular internuclear ophthalmoplegia (WEMINO) as "a unique clinical syndrome" characterized by unilateral INO and ipsilateral exotropia. WEMINO was clinically identified in seven patients, with oculographic correlation in six and neuropathological confirmation in one. Oculographic features of exotropic INO patients were compared with those of six orthotropic INO patients using magnetic search coil and infrared oculography. All clinically defined WEMINO patients showed slowed, hypometric ipsilateral saccades by oculography. Six patients had ipsilateral exotropia, and three had ipsilateral hypertropia. Ipsilateral abducting saccades had faster peak velocities for smaller saccades, more so for orthotropic patients. Exotropic patients had normal sinusoidal mean vestibulo-ocular reflex (VOR) gains and phases; orthotropic patients had subnormal mean VOR gains and phase leads. WEMINO is a clinical ocular motor syndrome characterized by unilateral slow, hypometric adducting saccades with exotropia and hypertropia of the ipsilateral eye. We propose that it results from discrete unilateral damage to burst-tonic fibers in the medial longitudinal fasciculus (MLF) with sparing of the adjacent extrafascicular pathways. Paradoxically, orthotropic INO results from more extensive damage to ascending pathways lateral, ventral and caudal to the MLF. Direct injury to the medial rectus subnucleus is not required. This manuscript was in preparation at the time of Dr Sharpe's death in 2013 and is an acknowledgement of his forward-thinking, as his hypotheses have stood the test of time.

Electron temperature and ion density distribution on a vertical section in a weakly magnetized inductively coupled plasma

In this study, the distributions of electron temperature and ion density on a vertical section in a weakly magnetized inductively coupled plasma were measured using radially movable floating probes placed at different axial positions. The chamber used in this experiment included two cylindrical parts: a smaller radius top part with a planar antenna on the top quartz window and a larger radius downstream part. A magnet coil around the chamber top part maintained a divergent magnetic field in the discharge region. As the current in the magnet coil increased, the magnetic field also increased. Due to the variations of the radio frequency electric field in the plasma, the increase in electron temperature can be divided into different stages. At the higher magnetic field, the electric field of the electrostatic wave can increase electron temperature at the chamber center axial. Also, since the electron cyclotron resonance (ECR) heating in the chamber downstream part changed with the magnetic field, the maximum ion density was observed when the magnetic field around the bias electrode was slightly larger than the ECR magnetic condition. The reasons for these variations were verified in the plasma numerical simulations. The ion flux distribution measured on the bias electrode can change from a center-high distribution to an M-shape distribution with the increased magnetic field.

Сверхпроводниковая электромагнитная система ИТЭР. Статус изготовления и сборки на 2024 год

The electromagnetic system (EMS) is one of the most significant components of the International Thermonuclear Experimental Reactor (ITER). It establishes the machine’s ability to generate and control a fusion plasma with a current of up to 15 MA and a power of up to 500 MW within hundreds of seconds. ITER EMS is the largest superconductor magnet system that has ever been created with a stored energy of up to 50 GJ. It is a highly technological magnets using superconductors based on Nb3Sn and NbTi, which work at a temperature of 4-6 K with compulsory cooling by a flow of liquid and gaseous helium. The EMS coils are required to be operable at electrical voltages up to 20-30 kV, and mechanical stresses up to 500-600 MPa. The manufacturing of the coils and the associated superconducting current carrying system are now moving into the final stage of production. The most part of them has already been manufactured and delivered to the ITER toroidal magnetic coil chamber (Tokamak) installation site. This review briefly describes the design of ITER superconductor coils of all 4 types and gives the current status of their manufacturing and assembly.

Numerical Optimization of Hall Effect Thruster with variation in Magnetic Field

In the present study, numerical analyses were conducted to enhance the strength of the magnetic field. While electromagnetic coils and permanent magnets have conventionally been used for this purpose, the study explores the utilization of superconducting magnets, known for their significantly stronger magnetic fields. Through analytical tests on a thruster powered by a 5-kW source at 400 V, and 12.5 A current, computer simulations are conducted using an open-source HallThruster.jl developed using Julia language which gave 1D simulation of plasma properties of Hall effect thruster (HET), along a thrust of 0.687 N was achieved representing a three times greater increase, and specific impulse increasing to 3097 sec which is 1.7 times more compared to conventional results, accompanied by improved plasma parameters. Furthermore, to study the particle behavior the Particle In cell (PIC) approach was utilized, from which particle motion due to the magnetic field was achieved. By enhancing the magnetic field, we can significantly boost thrust, unlocking new possibilities for exploring distant planets and conducting long-duration space missions. Utilizing superconducting materials ensures continuous, efficient operation with increased thrust and fewer operating payloads, ultimately enhancing overall spacecraft functionality. This advancement paves the way for future innovations in space exploration and applications.

Efficient Calculation of the Self-Magnetic Field, Self-Force, and Self-Inductance for Electromagnetic Coils

Efficient Calculation of the Self-Magnetic Field, Self-Force, and Self-Inductance for Electromagnetic Coils

Динаміка електрокерованих паливних клапанів реактивних двигунів малої тяги на «зеленому» паливі

Recently, the leading space countries have paid much attention to searching for and using new types of untoxic “green” propellants. Developments of 0.1 N to 220 N “green”-propellant thrusters have been reported, and some of them have been successfully tested in flight conditions. Liquid-propellant spacecraft thrusters are actuators of a spacecraft in-orbit motion control system. They are actuated from command signals of the spacecraft control system by applying a voltage to the electromagnet coils of the propellant valves of each of the engines that are to feed the propellant during a specified time interval to produce a required thrust impulse. A problem common to liquid-propellant thrusters irrespective of the propellant type is a thruster start-up delay with respect to the command signal and a thruster shut-down delay with respect to the electromagnet coil de-energizing. In other words, the thruster response is shifted with respect to the command signal. Because of this, the valve parameters must be chosen in such a way as to minimize the delay effect. The goal of this work is to determine design parameters of electrically controlled propellant valves that would provide an efficient in-orbit operation of “green”-propellant thrusters with a minimum of electric energy consumption. To determine these parameters, use was made of a branch standard, the procedure of work with which was based on empirical data and verified by numerical simulation. The key factor in shortening the thruster start-up delay is to reduce the seat-to-tip valve plate travel on condition that a required propellant amount is fed to the reaction chamber. However, this extends the shut-down delay, which has a harmful effect in the short-impulse operation mode. It is shown by calculation that after the electromagnetic parameters have reached their steady-state values, the voltage can be reduced by 30 to 40 per cent of its nominal value with the valve kept in an open state, after which the valve closes with a shorter delay. In addition, this way of valve energizing reduces the total electric energy consumption for valve operation. The mathematical model of valve dynamics allows one to determine the valve operation parameters in the case of short command signals probable in flight conditions. In such a case, a valve does not open to a full extent, which results in a low specific impulse. The results of this study may be used in the development of “green”-propellant thrusters.

A Control Strategy of Multiple Microrobots Using a Hybrid Electromagnetic System

AbstractMagnetic microrobots are controlled to exhibit a wide range of motions, allowing them to navigate complex environments and perform multifunctional tasks with high precision. This work presents a novel hybrid electromagnetic actuation system by integrating two distinct conventional configurations, such as a paired‐coils electromagnetic disc (EMD) system and a distributed electromagnetic array coil (EAC) system. In order to ensure the effective functioning of the microrobot, its motion dynamics are thoroughly analyzed to identify the critical kinetic parameters. For demonstration purposes, first, a mixing task is performed by employing a single microrobot actuated with simultaneous motions. The mixing efficiency is observed to reach 83% within 30 s, in contrast to the efficiency of control of 45%. Second, a structural reconfiguration function is demonstrated by employing an independent control of two U‐shaped microrobots to form a new I‐shaped microrobot. Last, differentiated motion control of multiple magnetic pads is demonstrated, resulting in various 2D static formations in the shapes of numbers and alphabets. The presented results hold great promise for advancing the field of microrobotics by offering a novel solution for versatile microrobot motion controls.

Development of a flexible phased array electromagnetic acoustic testing system with array pickups

The thermal barrier coatings (TBCs) used to protect blades of heavy-duty gas turbines is prone to debonding defects during fabrication and service. It is difficult to detect the debonding defects in the TBC system non-destructively and in situ due to the curved shape of blade and the narrow space between the blades setting in the gas turbine. In this paper, a flexible phased array electromagnetic acoustic (FPA-EMA) testing system with array pickups is developed, which is capable to drive a flexible phased array electromagnetic acoustic transducer (FPA-EMAT) to generate and receive ultrasonic wave directly in the metallic substrate of TBCs, and is potential to be applied to the inspection of debonding defects in the TBC system of gas turbine blades. A phased array excitation unit, a multi-channel signal receiving unit and a new signal post-processing algorithm are developed for the new EMA testing system to enhance the surface acoustic wave in the layered structure and to improve the low conversion efficiency of the conventional EMA testing system. In addition, a bias magnetic field coil fed with long pulse current of large amplitude is adopted to make the new EMAT thin and flexible in order to be applied in a narrow space. The interfering noise and geometric size problems brought by the multiple excitation and pickup channels are well addressed in the new system. The good performances of the developed FPA-EMA testing system were verified experimentally and show the system of good potential to be applied to NDT of practical curved structures.

Miniaturized Pathogen Detection System Using Magnetic Nanoparticles and Microfluidics Technology

Rapid detection of a biological agent is essential to anticipate a threat to the protection of biodiversity and ecosystems. Our goal is to miniaturize a magnetic pathogen detection system in order to fabricate an efficient and portable system. The detection device is based on flat, multilayer coils associated with microfluidic structures to detect magnetic nanoparticles linked to pathogen agents. One type of immunological diagnosis is based on the measurement of the magnetic sensitivity of magnetic nanoparticles (MNPs), which are markers connected to pathogens. This method of analysis involves the coupling of antibodies or antigen proteins with MNPs. Among the available magnetic techniques, the frequency mixing method has a definite advantage by making it possible to quantify MNPs. An external magnetic field composed of a low- and a high-frequency field is applied to the sample reservoir. Then, the response signal is measured and analyzed. In this paper, magnetic microcoils are implemented on a multilayer Printed Circuit Board (PCB), and a microfluidics microstructure is designed in connection with the planar coils. Simulation software, COMSOL version 5.3, provides an analytical perspective to choose the number of turns in magnetic coils and to understand the effects of changing the shape and dimensions of the microfluidics microstructure.