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Social-spider optimization (SSO) is a new nature-inspired algorithm of the swarm intelligence field to global optimization applications, which is based on the simulation of cooperative behavior of social spiders. To enhance the performance of the standard SSO, a modified SSO (MSSO) approach based on beta distribution and natural gradient local search was proposed in this paper. In order to verify the performance of the MSSO, tests using Loney’s solenoid benchmark and a brushless direct current motor benchmark are realized comparing the effectiveness of the SSO and the proposed MSSO. The results of this paper demonstrated that the MSSO performance is promising in electromagnetics optimization. [ABSTRACT FROM AUTHOR]

This paper presents an analytical calculation method for the computation of the magnetic vector potential of an axisymmetric solenoid in the presence of an iron shield and a ferromagnetic core. The proposed method can be used as a fast analytical computation technique for accelerating the design optimization process of the solenoid systems. In this paper, the analysis of the current carrying coil in the presence of the ferromagnetic materials is treated as a boundary value problem. The solution approach is based on partitioning the solution domain into distinct regions. The general form of the solution to Maxwell’s equation in each region along with the corresponding boundary conditions is obtained using the Fourier analysis and the separation of variables. The final solution to the boundary value problem is constituted by considering the continuity of the magnetic vector potential, as well as the magnetic field, on the interfaces between the regions. Finally, the proposed analytical computation method is applied on an electromagnetic actuator. The magnetic vector potential is computed over the entire solution domain, and the result is compared with that of the finite-element method. [ABSTRACT FROM AUTHOR]

This paper introduces a primary pad for wireless charging applications, which is able to transfer high power over large air gaps and is tolerant to lateral displacements suitable for electric vehicle charging applications. The developed pad is an improved solenoid designed specifically to address issues such as flux leakage and loss while retaining good coupling. It is a hybrid structure that consists of a combination of rectangular- or square-shaped coils and a central solenoid, all connected in series. When energized, it produces a single-sided, polarized flux similar to the flux pattern of the solenoid and double D (DDP) pads. The power transfer capability of this pad is investigated through finite-element analysis simulations. The results are compared first to a similar sized solenoid from which it was derived, and also a DDP primary pad and are verified through measurements on prototype systems in the laboratory. The aim of this paper is to provide an improved hybrid solenoid pad showing higher coupling factors and lower stray field emissions with a performance (coupling and stray field emissions) similar to that of DDPs. [ABSTRACT FROM AUTHOR]

This paper proposed the use of a ringer, a self-switched inductive storage system, for applications involving reluctance accelerators, a kind of electromagnetic launcher, and compatible with applications where portability is a requirement. There will be shown three different useful approximations for the analysis of the ringer, employed as a power source for a reluctance accelerator. First, it described the equations governing the que behavior of an ideal unloaded ringer, and then the equations for the ringer with an uncoupled inductive load, and ultimately a Lagrangian model for the ringer as an inductive power source for a reluctance accelerator, capable to make predictions about the currents through the circuits and the exit speed of the projectile for a given firing. The accuracy of the predictions made with the third approximation, the Lagrangian model, was tested experimentally. [ABSTRACT FROM AUTHOR]

According to the Chinese fusion engineering testing reactor (CFETR) central solenoid model coil (CSMC) properties test requirements, a large cryogenic test platform will be built. The feeder, as one of the important components of the platform, should be studied to afford the much valued help for the basic test facilities. This paper focuses on the feeder structural design and the stress analysis in conditions of different loads. All of the work could not only provide necessary help for building CFETR CSMC test platform but also provide the important service experience of the large cryogenic test platform in the future. [ABSTRACT FROM AUTHOR]

In this paper, we propose an efficient procedure to obtain loop and star basis functions useful to the surface integral equation. They are of any order, for 3-D curved surfaces, and they keep the solenoidal/nonsolenoidal splitting, improving the performance for low frequencies (near field). These bases, introduced in a former work and applied to the electric field integral equation (EFIE), herein are used in both the magnetic field integral equation (MFIE) and the combined field integral equation (CFIE) providing a good performance even at the low-frequency regime. For addressing the low-frequency performance, scale factors and normalization of the basis are applied to EFIE, MFIE, and CFIE formulations. [ABSTRACT FROM AUTHOR]

Leakage and magnetizing inductances of transformer windings are routinely measured by power utilities during scheduled maintenance. They are often used to confirm the diagnosis of mechanical damages in windings after Swept Frequency Response Analysis shows a mismatch. Inductance measurements performed at power frequency can possibly reveal the presence of damages that have substantially progressed but cannot detect them at their nascent stages since inductances at power frequency remain almost unaltered. This paper investigates the possibility of using high-frequency inductance to this end considering a frequently encountered mechanical damage, viz., disk-space variation in a disk winding. Effect of disk-space variation is investigated in this article using FEM at first and inductances at different frequencies are considered: magnetizing and leakage inductances at 50 Hz, and inductance at a higher frequency region corresponding to winding resonances, say, 500 kHz. The inductance at high frequencies not only exhibited increased sensitivity compared to that at power frequency, but also captured the extent of damage. Simulations performed using Ansys Maxwell and experimental results on an actual 1- $\phi$ transformer are reported. Results show that the high-frequency inductance not only offers a considerably increased sensitivity to disk-space variation in windings compared to the power frequency inductances, but also provides insight regarding the extent of movement which is not apparent from the frequency response. [ABSTRACT FROM AUTHOR]

The Center Solenoid Model Coil (CSMC) is a pre-research project of CFETR, and its task is to design and manufacture the CS superconducting model coil to gain wider experience in solving the related technical problems existing in design and construction of CFETR CS coils. The expected achievement is to charge the CSMC up to the operation current of 47.65 kA and the maximum magnetic field to 12 T with a swift rump rate of 1.5 T/s without quench. Quench detection by voltage measurements is likely to be the fastest available technical solution to avoid coil's damage caused by quench, but the voltage detection is a real challenge due to large noise induced by the power supply in alternating current operation. The pick-up sensors, comprising the co-wound wire (CWW) and the co-wound tape (CWT), are used in the CSMC quench detection system for noise compensation and suppression. To accurately compensate all related induced voltage in the multi-pulse coil system, the foremost task is to estimate the static inductance matrix between the CSMC and its pick-up sensors. In this paper, a numerical model is developed for inductance calculation and analysis. Moreover, several numerical simulations with this design model to evaluate the maximum inductive noises and quench detection signals by CWW and CWT have been conducted for the case of the worst test scenarios. [ABSTRACT FROM AUTHOR]

In this paper, we aimed to develop a pulsed electromagnetic field (PEMF) system and to investigate its effects on diverse cell types. To ensure uniform magnetic flux density in the space for cell culture, the PEMF system was designed with an efficient solenoid using an analytical design and finite-element analysis. We investigated its effects on diverse cell types by using cell proliferation assay and flow cytometry analysis. The results of this paper show promise in furthering the PEMF-related biomedical research and its applications in translational studies. [ABSTRACT FROM PUBLISHER]

The thrust ripple in a permanent magnet linear synchronous motor (PMLSM) is mainly generated by the detent force that is caused by the interaction between the permanent magnet (PM) and the iron core without input current in armature winding. This paper proposes two different techniques to minimize the detent force in a PMLSM. One is to choose an optimal constructive design; the other is to employ a current compensator. In this paper, we investigate the performance of detent force minimization using both of them. The effectiveness is verified by both numerical and experimental results. [ABSTRACT FROM AUTHOR]

The central solenoid model coil (CSMC), a crucial component of China Fusion Energy Test Reactor, is currently in the design and manufacturing process. CSMC assembly consists of a number of steps such as winding pack, an outer NbTi coil, a middle Nb3Sn coil, an inner Nb3Sn coil, and a preload structure. The highest field of the model coil is 12 T with the maximum change rate of a magnetic field of the conductor is 1.5 T/s. In this paper, length of the cooling channels together with thermal–hydraulic parameters such as inlet pressure, temperature, and mass flow rate are optimized. In addition, thermal–hydraulic analysis for the cooling loop located in the worst condition of the model coil was conducted to recognize the temperature and mass flow rate change over time. The hydraulic model, the material properties, and the heat loads associated with analysis are given, and the results of the analysis are presented. [ABSTRACT FROM AUTHOR]

RF sources are used in many applications, including high-power radar, communications, cancer therapy and diagnosis, electronic countermeasures, and high-energy accelerators. Many of these sources are located in well controlled environments where high-quality coolant fluids are readily available. Others, however, are located on platforms where harsh environmental conditions exist, and high-quality coolants are not easily provided. This includes ships at sea and remote transmitters in the second-world and third-world countries. Corrosive ethylene glycol mixtures may be required where extreme temperatures are encountered. Essentially, all high-power RF sources are fabricated from brazed copper structures, which are particularly susceptible to corrosion from corrosive coolants. This paper demonstrates using atomic layer deposition (ALD) to deposit nanometer-scale ceramic coatings inside coolant passages to separate the coolant from the underlying metal surface. This effectively reduces or eliminates corrosion and erosion, thereby increasing lifetime and reliability of RF sources. We describe ALD equipment and process specifically focused on RF sources and related components. The results of numerous experiments are reported, confirming the efficacy of the technology. [ABSTRACT FROM AUTHOR]

In order to verify key techniques and manufacturing aspects of the central solenoid (CS) coil of the China fusion engineering test reactor (CFETR), the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) plan to develop a CS model coil. The conceptual design of the CS model coil of CFETR has been carried out by ASIPP. The CS model coil shall produce a 12-T peak field in the bore of the magnet. The maximum magnetic field change rate is 1.5 T/s. The designed operating current is 47.65 kA. The CFETR CS model coil structure design mainly includes coil winding design, buffer zone design, preload structure design, coil joints and joint supports design, and liquid helium cooling channels design. This paper presents the conceptual design of CFETR CS model coil structure based on electromagnetic design and optimization. [ABSTRACT FROM AUTHOR]

In this paper, a thin superconducting solenoid is used to provide magnetic field in the CMD-3 particle detector. The solenoid is powered by a full-wave ac-dc superconducting rectifier. The rectifier is a current step-up superconducting transformer with two thermally controlled superconducting switches connected to its secondary windings. TheCMD-3 solenoid is indirectly cooled, therefore the indirect cooling method is used for the rectifier as well instead of a conventional liquid helium bath. The rectifier charges and discharges the solenoid, and provides long-term magnetic field stabilization. The CMD-3 solenoid operational magnetic field is 1.3 T with 927 A current. The rectifier charges the solenoid to this field within 7 h. Achieved long-term stability of the field is 2 × 10-5 T. The rectifier has been demonstrating good reliability since 2010, when the magnet system of the CMD-3 had been commissioned. Design, test results, and performance of the rectifier are reported in this paper. [ABSTRACT FROM AUTHOR]

The Institute of Plasma Physics, Chinese Academy of Sciences was contracted by General Atomics Company to develop a superconducting feeder system containing a pair of 50-kA high-temperature superconducting (HTS) current leads for ITER central solenoid magnet test. These HTS current leads (HTSCL) are based on the previous ITER lead design experiences. However, the vertical assembly design of HTSCL which is different from ITER's horizontal assembly causes the water leakage in the insulation flange during the initial phase. Some improvements were recognized and expected to avoid the potential risk for further prototypes and series production of ITER leads. Some development experiences are shared in this paper. The HTS current leads contain BiSCCO AgAu matrix tapes tominimize the heat load to 4.5 K end. Its resistive part is cooled by 50-K helium. In the HTS part, the conduction cooling is adopted. The HTS current leads were integrated in the feeder system to perform 4.5-K full current test. The factory acceptance test was implemented to verify the highvoltage and thermodynamic performances. The maximum current of 55 kA was achieved. The test indicates that the helium mass flow consumption is 3.3 g/s per lead and the loss of flow accident time is approximate to 10 min at the nominal current with the stoppage of 50-K helium. The insulation flange passed the high-voltage test of 15 kV, while the leakage current is less than 1 mA after the improvement. More detailed test results will be shown in this paper. [ABSTRACT FROM AUTHOR]

The ITER Central Solenoid (CS) consists of a stack of six independent coil packs called modules. It features a total height of 18 m and a diameter of over 4 m. The modules are in an advanced stage of fabrication and testing by the US ITER Project Office (USIPO) and its subcontractor General Atomics (GA). A qualification module mockup at one to one scale but of reduced height was wound and Vacuum Pressure Impregnated (VPI) by GA to validate final manufacturing, using tooling and processes fully representative of a series module. The module was submitted to a thermal cycle down to the temperature of 4.5 K at which the coils will be cooled by supercritical helium. During plasma operation, the CS modules are subjected to a complex combination of static and dynamic forces. The understanding of the mechanical behaviour of the CS module coils is of paramount importance to analyse and predict the overall response of the CS stack. To this purpose, an extensive programme of investigation of the module mockup has been defined and applied. This allowed assessing, through examination and testing of a large number of VPI conductor array samples extracted from the mockup, the soundness of the coil through advanced non-destructive examination techniques including X-ray microtomography, dimensional metrology measurements and micro-optical observations. Moreover, additional testing of physical and mechanical properties carried out at room and cryogenic temperature allowed the behaviour of the conductor stacks to be assessed. The paper summarises the results of these investigations and their interpretation through mechanical analyses based on the individual properties of the coil constituents. [ABSTRACT FROM AUTHOR]

The electron cooling technology is applied in the spectrometer ring (SRing) to improve the luminosity of ion beam for the High Intensity heavy-ion Accelerator Facility (HIAF). The electron cooler consists of a gun section, two 90-degree toroids, a cooling section and a collector section. There are four kinds of main coils used to provide longitudinal magnetic fields along the path of the electron beam. In this paper, we present the modeling and analyzing of the electron cooler magnets by three-dimension software. The optimizing of the magnetic field of cooling section is completed to achieve the required effective cooling length. The magnetic fields along the electron beam path and ion beam path are calculated and the beam trajectory of typical ion is also simulated to offer data for correcting the orbit. [ABSTRACT FROM AUTHOR]

Although motors that use rare-earth permanent magnets typically exhibit high performance, their cost is high, and there are concerns about the stability of the raw material supply. This paper proposes a permanent-magnet-assisted synchronous reluctance motor (PMASynRM) with a ferrite magnet that does not use rare-earth materials considering productivity. The performance of the proposed PMASynRM is evaluated based on the finite-element method and an experiment using a prototype machine. The analysis results reveal that the proposed PMASynRM has the same power density and an equivalent efficiency as rare-earth permanent-magnet synchronous motors for hybrid electric vehicles (2003 Toyota Prius). Furthermore, some experimental results are presented in order to validate the analytical results. As a result, the proposed PMASynRM was found to achieve high-power-density and high-efficiency performance. [ABSTRACT FROM AUTHOR]

It is attractive to use sheet beam vacuum devices to generate high frequency, high-power microwave radiation. In this paper, we present the numerical and experimental studies of a high-power Ka-band sheet electron beam backward wave oscillator (BWO), in which the double-grating rectangular waveguide is used as the slow wave structure (SWS) for its thermal and mechanical robustness. The fundamental mode of this kind of SWS is an antisymmetric mode which has an antisymmetric longitudinal field distribution and will nonsynchronously interact with the electron beam on two sides of the electron channel along the vertical direction. We put forward a method to overcome this trouble in this paper. To drive this BWO, a high-power sheet beam is used with a cross section of 30 mm $\times\,$ 1 mm. A thin graphite cathode is used for its superiority in producing a high current, high-quality electron beam. For an experimental electron beam of 141 kV and 1668 A, the output power of over 46.8 MW at 31.68 GHz is obtained, which corresponds to a beam–wave interaction efficiency of 19.9%. Compared with the conventional hollow beam BWO and the single-grating rectangular waveguide sheet beam BWO, the double-grating sheet beam BWOs efficiency is higher, which indicates that the double-grating sheet beam device is promising for producing millimeter wave radiation with high power and high efficiency. [ABSTRACT FROM PUBLISHER]

A novel magnetic vector potential (MVP) formulation with Coulomb gauge is proposed for solving 3-D magnetostatic problems. A dummy scalar variable is introduced in the whole computation domain to impose the Coulomb gauge. Unlike traditional Coulomb-gauged formulation using the penalty technique, which works only for nodal elements approximation of the MVP, the new formulation proposed in this paper allows the use of edge element approximation of the MVP. It can avoid possible large errors at material interfaces or re-entrant corners of the problem domain when using nodal discretizations for the MVP. This formulation is easy to implement, and the resultant matrix system is symmetric with a unique solution. Both linear and nonlinear numerical examples are presented to showcase the accuracy and usefulness of the proposed method for engineering computation. [ABSTRACT FROM AUTHOR]

This paper proposes a new design optimization method for a magnetic actuator based on a hybrid analysis method. The equivalent circuit method and the finite analysis method are combined to create a design method that is both accurate and efficient. The driving performance of the magnetic actuator is predicted through the use of simple circuit parameters, and the specific flux distribution required to obtain a detailed design is calculated only in the design domain, where finite elements are located. The magnetic potential, obtained from lumped circuit parameters, is used to set the boundary conditions of the design domain and for calculating the topological design sensitivity. Since the objective function and design constraints are defined using circuit parameters and the topological variable in the hybrid analysis model, the optimization problem is separated into two phases, to deal with two types of field variable. A simple design example of a solenoid-type actuator is provided to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, the effect of external magnetic field loaded at the initial period of inertial stretching stage on a jet produced by Ø56-mm shaped charge is evaluated through the depth-of-penetration (DOP) test method. Experimental results are compared with the results obtained under the field loaded at the later inertial stretching stage. A standoff of 650 mm is used in the experiments, in which the shaped charge jet can undergo formation, elongation, breakup, rotation, and drift. The initial energy is provided by a capacitor bank, which is loaded on the solenoid to generate a magnetic field used for coupling with the jet. The external magnetic field loaded at the initial period of inertial stretching stage can enhance the stability of the jet and increase its DOP. The penetration capability of the jet in the above-mentioned condition is increased by 77.4%. [ABSTRACT FROM AUTHOR]

A new model of the radio frequency identification antenna using the solenoid coil, surrounded by a coaxial ferrite toroid, is proposed in this paper. The truncated region eigenfunction expansion method is adopted to derive the expressions of the magnetic vector potential. Besides, due to the low conductivity and high permeability of the ferrite, a convenient solution region division is introduced to avoid solving the transcendent eigenvalue equation caused by the end effect as usual. Numerical calculations are performed, and the results are in excellent agreement with those obtained from the finite-element method simulations. [ABSTRACT FROM AUTHOR]

An electromagnetic proportional solenoid is used as a force control device to generate thrust force acting on a valve element in a hydraulic pressure control valve. However, a conventional proportional solenoid has the problem of hysteresis appearing in its current–thrust force characteristics, which is induced by friction and magnetic hysteresis. In order to reduce hysteresis, this paper proposes the three-phase ac solenoid that reproduces a pseudo-magnetic bearing. Its prototype reduces hysteresis and achieves the same performance as the conventional proportional solenoid. The magnetic pole shape and the current input condition considering the magnetic flux density saturation are presented based on electromagnetic field analysis. [ABSTRACT FROM AUTHOR]

A fast and accurate calculation of the resonant frequency of a solenoid coil is needed in many applications, e.g., wireless power transfer and magnetic resonance imaging. It helps to accelerate the design and optimization of a coil. However, the existing calculation models for the key equivalent parameters, the inductance ($L$) and the capacitance ($C$), of the solenoid coils can only provide estimations for standard tightly wound cylindrical coils, and the accuracy is not high. There are no accurate models available for calculating $L$ , $C$ , and the resonant frequency when a solenoid becomes irregular, e.g., when it is sparse (with a large pitch), when it has nonuniform pitches, or when it is noncylindrical. In this paper, we propose a fast and accurate model for such an irregular solenoid coil to calculate its inductance, capacitance, and, thus, the resonant frequency. The accuracy of the proposed model is tested on the solenoid coils (with large pitches, nonuniform pitches, or noncylindrical shape) by comparing the calculated results to those using commercial simulation software and the measurement results. For a sparsely wound solenoid, the proposed model provides an accurate calculation of the inductance with a maximal pitch-to-wire-diameter ratio of 40 (an error rate of 8.33% at this ratio). For a varied-pitch solenoid and a noncylindrical one, an error rate of less than 5% can be achieved for a calculation of the inductance. [ABSTRACT FROM AUTHOR]

This paper describes the development of a new magnetometer calibration device using an active magnetic field compensation technique based on the base quantity of time rather than secondary standard field measurements. The proposed arrangement can be used as a laboratory calibration device that monitors and compensates the ambient dc magnetic field in a magnetically quiet environment. Furthermore, it can be developed to serve as a laboratory primary standard since it is based on the measurement of a base quantity, such as time. The proposed technique is based on the fluxgate magnetization principle and the measurement of the time difference between the two successive output pulses. The laboratory arrangement consists of a long solenoid for 1-D applications, which may be extended to 2-D and 3-D using Helmholtz coils, and a microcontroller for fast signal processing operations, which evaluate and compensate the detected ambient magnetic field using a closed-loop control algorithm. The proposed arrangement is used to obtain the calibration curves of a commercial Hall and a custom-made fluxgate sensor. [ABSTRACT FROM AUTHOR]

In this paper, a novel active shimming method is proposed to minimize the shim coil–magnet and the shim coil–shim coil magnetic couplings simultaneously. In standard superconducting shim coil designs, each shim coil is usually designed individually to correct specific field harmonic components of the inhomogeneous field without considering the magnetic couplings among the shim coils and the main magnet. In particular, a strong interaction among the zonal shim coils and the main magnet can lead to a series of problems, like the drift of main field, instability of field homogeneity, and even destruction of coils. In this paper, magnetic decoupling techniques for reducing magnetic interactions among the zonal shim coils and the main magnet are developed. To complete a set of independent shim coils design, a nonlinear optimization model considering the field deviation and magnetic coupling is established. To improve the efficiency and solution quality of the involved optimization problem, the nonlinear model is first converted to a linear one by using the McCormick envelopes scheme. Through linear programming (LP), the optimal topology and preliminary positions of the shim coils are determined. To further optimize the position and turn numbers of the shim coil, a nonlinear programming (NLP) is then implemented to achieve desired field uniformity. In order to verify the feasibility and effectiveness of the proposed method, a simulation design of two sets of shim coils, Z2 and Z4, for a practical 9.4T magnet for whole-body magnetic resonance imaging (MRI) is presented. Compared with coils designed by conventional methods, magnetic coupling between the zonal shim coils and the main magnet had been effectively reduced. And also, magnetic coupling between the zonal shim coils had also been minimized as much as possible, which consequently improve the stability and safety of the MRI magnet system. [ABSTRACT FROM AUTHOR]

The superconducting magnetic energy storage (SMES) system technology has the potential to bring real power storage characteristic to the utility transmission and distribution systems. The principal object of this paper is to provide a positive approach in an optimized design of a SMES solenoid coil, ensuring the desired energy storage capacity based on the normalized simulated annealing (SA) algorithm. The optimization algorithm for simultaneous optimization computes and produces 2-D alignments in the Pareto front at the end of the optimization run. The optimization process of the normalized SA algorithm is verified by another strategy algorithm, i.e., the nondominant sorting genetic algorithm. In both strategies, simultaneous optimization will show a set of feasible solutions in Pareto optimality in SMES solenoids. Hence, this requires field analysis for verification of the Pareto optimality design. Moreover, to provide inadequate free space surrounding the area where stray field reduction is desired, aiming simultaneously at compactness and efficiency of the SMES system (the approach of a stray field cancellation (active shielding) scheme by modeling multiparallel solenoids), is a further object of this paper. [ABSTRACT FROM AUTHOR]

Magnetic flux leakage (MFL) testing is a widely applied method for the ferromagnetic specimen defect detection. In this paper, we present a solenoid analytical model to MFL field based on the molecular current model of a magnetic medium. This model applies $B$ – $H$ characteristics of the material to confirm the homogeneous magnetization of the specimen and to obtain the magnetic moment of solenoids, and then it uses a semi-infinite solenoid as the source to simulate the leakage field. Furthermore, this model proves that the edge effect and defect geometry can be represented properly by setting ellipsoid defects at different positions in the specimen. The results of the proposed model are influenced not only by defect shape as that of the magnetic dipole model but also by the relationship between the magnetization and the normal direction of the defect surface, which leads to the more accurate reconstruction of defects. Based on these findings, the error from the assumption of homogeneous magnetic dipole distribution or magnetization can be explained by the solenoid interaction. This explanation provides a new way to eliminate the computation error, and the solenoid model shows higher computational efficiency compared with the numerical model. [ABSTRACT FROM AUTHOR]

This paper aims to realize compact actuation systems by sensorless approach. This study adopts solenoid actuators which have advantageous characteristics from the view point in inexpensive cost, simple structure, and high-output force in spite of difficulty in low cost position and force sensing. Some sensorless position estimation techniques for solenoid actuators were reported. However, position and force simultaneous estimation has not sufficiently been achieved. In addition, any real-time feedback control has not been reported. This paper proposes sensorless feedback position control for compact solenoid actuators. The force generation and position/force estimation are conducted by using a dc supply power superposed by an ac component. This control technique has three main features: 1) separation of the power supply into ac and dc components for the position estimation, 2) simultaneous real-time estimation of position and force, and 3) robust feedback position control. Simulations and experiments were conducted for verification of the proposed control with the above three features, and the results indicated that error between the estimation and actual positions was within 0.2 mm. This proposed system offers a new avenue for compact and inexpensive application field. [ABSTRACT FROM PUBLISHER]

Transcranial magnetic stimulation (TMS) is a non-invasive, surgery-free, and safe treatment for major depressive disorder. There is a need to develop coils, which can stimulate deep brain regions for the treatment of other neurological disorders, such as Parkinson’s disease. Stimulation of the deep brain regions cannot be directly tested on human subjects without successful animal trials. In this paper, seven mouse TMS coils were compared and their electric and magnetic fields in the brain were calculated. Coils, such as “Slinky” coil and “V” coil, stimulate small and outer layers of the mouse brain, while “Animal Halo” coil stimulates $\sim 90$ % of the mouse brain. This comparison between the coils enables researchers to choose the right coil according to their need, such as the depth of penetration or the focality of brain region to be stimulated. [ABSTRACT FROM PUBLISHER]

This paper presents the design and electrical performance of transformers with magnetic thin films for on-chip power conversion and isolation. The inductance of the devices is greatly enhanced by the use of a high-permeability magnetic material as a solenoid core, resulting in an inductance density of 108 nH/mm2. The total thickness of the transformer structures is <30~\mu \textm with a volume inductance density of 3.6~\mu \textH /mm3. By laminating the magnetic core, losses are well controlled leading to a peak quality factor ( $Q$ ) of 16 at 40 MHz. [ABSTRACT FROM PUBLISHER]

A modular, mid-power, Ka-band frequency (27–40 GHz) gyrotron is reported. The gyrotron is known as a dominant tube for millimeter waves, but once fabricated its frequency changing is limited. In this paper, a gyrotron with a replaceable resonator was designed and built. By a rather simple action of resonator replacement, the operating frequency of the gyrotron can be replaced. The use of a ferroelectric cathode supports a quick opening and closing of the tube for the resonator replacement in less than half an hour. With the view of covering a wide range of frequencies, a wide range magnetic field pulsed copper solenoid was designed, supporting the gyrotron operation on either the fundamental or the second harmonic of the electron-cyclotron frequency. The gyrotron design is based on a ferroelectric electron gun designed and built to provide the appropriate electron beam to a wide variety of resonators, operating at the fundamental or at the second harmonic. The gyrotron with two differently designed resonators has been constructed and tested in the TE01, TE21, and TE11 modes at 39, 31, and 27 GHz, respectively. With an accelerating beam voltage of −35 kV and a beam current of $\sim 1$ –1.7 A, an output power of \sim 1$ –6 kW was obtained at single pulse and at \sim 200$ -ns micropulse in \sim 6 macropulse with $\sim 25$ % duty cycle. In addition, the system was operated with 5-s repetition rate for half an hour, and a high stability was measured for all the mentioned frequencies. [ABSTRACT FROM AUTHOR]

A strong homogeneous magnetic field is required for a gyrotron as well as other applications. For many applications, the natural solution is a superconducting magnet, but for some applications, this solution is not suitable. In this paper, a copper-based design of a continuous, strong magnetic field source is presented. The design is based on a spaced Bitter solenoid with various radii, and with a transversely flowing cooling system. The results of the design are ±0.19% homogeneity over a length of 25 mm, and a power consumption of 12.2 kW for continuous operation. These results show that such a concept is applicable for a 95-GHz gyrotron operating in a long pulse or even continuous mode. [ABSTRACT FROM PUBLISHER]

Some evidence has demonstrated that focal vibration (FV) plays an important role in the mitigation of spasticity. However, the research on developing the FV system to mitigate the spasticity effectively has been seldom reported. To relieve post-stroke spasticity, a new pneumatic FV system has been proposed in this paper. An image processing approach, in which the edge of vibration actuator was identified by the Canny edge detector, was utilized to quantify this system’s parameters: the frequency ranging from 44 Hz to 128 Hz and the corresponding amplitude. Taking one FV protocol with the frequency of 87 Hz and the amplitude 0.28 mm of this system as an example, a clinical experiment was carried out. In the clinical experiment, FV was applied over the muscle belly of the antagonist of spastic muscle for twelve chronic spastic stroke patients. Spasticity was quantified by the muscle compliance and area under the curve for muscle (AUC_muscle). The result has demonstrated that, in the state of flexion of spastic muscle, the AUC_muscle and muscle compliance of the spastic muscle significantly increased immediately after FV compared with before-FV, illustrating the mitigation of the spasticity. This study will not only provide a potential tool to relieve post-stroke spasticity, but also contribute to improving the sensory and motor function of patients with other neurological diseases, e.g. spinal cord injury, multiple sclerosis, Parkinson and dystonia, etc. [ABSTRACT FROM AUTHOR]

The Deep Underground Neutrino Experiment (DUNE) at Fermilab is one the most challenging next-generation experiments in the field of neutrino physics. It will feature two detectors for a detailed study of neutrino oscillations using an unprecedentedly intense neutrino beam. The two detectors are a Near Detector located on the Fermilab site, 574 m away from the neutrino generation, and a Far Detector in South Dakota, 1300 km away. The Near Detector consists of three subdetectors, based on different technologies in order to achieve the best understanding of the neutrino beam. One key element of the Near Detector is a High Pressure Argon TPC surrounded by a calorimeter. This detector will need a 0.5 Tesla magnetic field transverse to the neutrino beam direction, with a 7 m diameter, 8 m long warm bore. A thin superconducting solenoid with a partial yoke, needed in order to minimise the amount of material along the path particles take crossing the different elements of the Near Detector is proposed. In this paper we present a detailed magnetic analysis and a preliminary study of the cooling, the cable and the mechanics for this magnet. [ABSTRACT FROM AUTHOR]

The ITER Central Solenoid (CS) will be manufactured by assembling a stack of six modules, which are under fabrication by the US ITER organization and its subcontractors. The tests of the first CS Module have been performed at the premises of the General Atomics (GA) facility in Poway (US), in order to check compliance to the ITER requirements. Among other tests, the magnet was submitted to exponential dumps of the transport current from different initial values (10, 15, 20, 22.5, 25, 35, 40 kA) down to 0 kA. These tests are aimed at conducting DC breaker commissioning of the test facility and were used to measure the AC losses in the coil during electrodynamic transients. This paper presents the results of these measurements, along with a comparison with analytical computations of the losses in the magnet. [ABSTRACT FROM AUTHOR]

The ITER Central Solenoid (CS) modules are under fabrication by the US ITER organization and its subcontractors. US ITER will supply seven modules to the ITER Organization (IO), six of which will be assembled in a stack that forms the ITER Central Solenoid, the last one being spare. The first module, namely CSM 1 was manufactured by General Atomics (GA) and went through Factory Acceptance Tests (FAT) including high voltage testing, Paschen testing and then cold test at 4.5 K and up to 40.0 kA in order to demonstrate compliance with coil performance requirements. The paper focuses on the results of the first CS Module thermal hydraulic characterization without current (and field). Pressure drops, transit time, and thermal coupling between pancakes are presented. Analysis results and tests are also compared. [ABSTRACT FROM AUTHOR]

The last acceleration stage of the deuteron beam of the LIPAc linear accelerator is provided by eight superconducting cavities in a cryomodule (SRF Linac). Each cavity needs a magnet package, which consists of a solenoid for beam focusing and two vertical and horizontal dipole correctors for beam steering. The superconducting coils are fed by vapour cooled current leads. The beam position monitor is part of the magnet helium vessel. The series fabrication of eight sets of magnets and current leads has been performed by Elytt Energy, under CIEMAT follow-up. This paper describes the final design used for production, the main challenges addressed during fabrication, together with the quality control procedure, acceptance tests and qualification criteria to validate both the magnets and current leads. Currently some activities are being performed in the magnet helium vessels for improvement of surfaces for handling inside the clean room and reducing the risk of presence of particulate contaminations in the beam tube. [ABSTRACT FROM AUTHOR]

The construction of a magnet system for the tokamak device of JT-60 super-advanced (JT-60SA) was completed in March 2020. The manufacturing of central solenoid (CS) had been finished in March 2019. The circularity of 4.0 mm is a requirement for CS manufacturing from the point of view of plasma control. The high accurate manufacturing method and jigs had been developed, and the circularity of CS achieves 1.44 mm, which meets the requirement of 4.0 mm. The clearance between the CS and the TF coils is very small, only 14 mm in design. In case the CS touches the TF coils and is subjected to load during operation, the CS can be damaged. Thus the surface dimensions of the CS and the TF coils have been measured before the installation of CS to confirm if the clearance is sufficiently large to avoid the CS crashing into the TF coils. The CS was successfully installed to the tokamak center without any damages in December 2019 as the final step of the magnet assembly of JT-60SA. In this paper, the manufacturing results and the installation of the CS are described. [ABSTRACT FROM AUTHOR]

The central solenoid model coil (CSMC) for China Fusion Engineering Test Reactor (CFETR) is being developed in the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The maximum magnetic field is 12 T in the bore of the Nb3Sn coils. It has a 1.5 T/s changing rate under 47.65 kA operating current. It was designed as a hybrid superconducting magnet with Nb3Sn and NbTi coils to reduce cost. The detailed structure of the CSMC has been designed, it mainly including Nb3Sn coils, NbTi coils, preload structure, coil buffer zone, joints, supports, feederthroughs, helium pipes and pipe supports. The preload structure consisting of 15 preload beams, 30 preload rods and support plates. And a 75 MN preload force will be applied on the preload structure at room temperature. This paper describes the final design of the Central Solenoid Model Coil. And the mechanical analysis results show that the final design is reasonable and feasible. [ABSTRACT FROM AUTHOR]

The Central Solenoid (CS) model coil, which is used to develop and verify the larger-scale superconducting magnet technology of China Fusion Engineering Test Reactor (CFETR), has been designed and is currently being manufactured at ASIPP. In case of an emergency shut-down like in succession of a quench, the voltage across the coil may rise to about 2.1 kV. Therefore, the coil has to be provided with a reliable electrical insulation. The electrical insulation systems of the CS model coil consist of turn, layer, and ground insulation. The insulation electrical performance tests are required to carry out at different stages of the manufacturing process to verify the insulation performance of the model coil. This paper gives the description of the insulation system, the applied and proposed test procedures. The test process of the electrical qualification test on mock-up coil is introduced. The test results are analyzed to verify the feasibility of insulation system design and manufacturing. [ABSTRACT FROM AUTHOR]

A central solenoid model coil (CSMC) is being developed to verify the large-scalar superconducting coil manufacture technology for China Fusion Engineering Test Reactor (CFETR) in Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The turn insulation wrapping of the Nb3Sn pancake coil is conducted after the coil heat treatment. The turn releasing technology is necessary to be developed and verified to insure there is no damage to Nb3Sn conductor during the turn insulation wrapping of the Nb3Sn pancake coil. This paper introduces the design, analysis and verification for the safe stretch distance, the design and debugging of the special equipment, and the process experiment with the 4 × 4 mockup coil. [ABSTRACT FROM AUTHOR]

The parameters of electrical machines can change considerably during operation due to thermal effects. Therefore, the corresponding models and the estimates of parameters can be subject to a significant bias and uncertainty, which degrade the performance of the system. In this paper, a method is developed to estimate the resistance of the coil of a linear electromagnetic actuator, i.e., of a single-coil linear solenoid. In the electrical model of the solenoid actuator, the inductance depends on the current. The inductance is identified from the transient waveform of the current (step response), and an estimate of the resistance is provided by extrapolating to the steady state of the current. Thus, the resistance can be estimated before the system reaches the steady state. The presented method is generalized to pulsewidth-modulation (PWM) drive conditions by considering the average of the current of the coil in the successive PWM cycles. This improves the suppression of measurement noise. The developed approach is demonstrated through numerical and experimental analyses. [ABSTRACT FROM PUBLISHER]

Brain storm optimization (BSO) is a novel population-based swarm intelligence algorithm based on the human brainstorming process. BSO has been proven feasible and has been successfully applied to benchmark problems in the electromagnetic field. In this paper, inspired by the mechanism of quantum theories, a novel variant of BSO algorithm, called quantum-behaved BSO (QBSO), is proposed to solve an optimization problem modeled for Loney’s solenoid problem. The new mechanism improves the diversity of population and also utilizes the global information to generate the new individual. Simulation results show that QBSO has better ability to jump out of local optima and perform better compared with the basic BSO. [ABSTRACT FROM AUTHOR]

A rotameter is a variable area type flow sensor. It is generally used as a local indicator and display unit. Hence, a special technique is needed to transmit and to display the reading of a rotameter at a remote distance. In this paper, an improved inductance bridge-type technique has been developed to convert the float movement of the rotameter into an electrical current signal, which can be transmitted to a remote indicator. A straight ferromagnetic wire attached to the float of the rotameter acts as a sensing element of the proposed rotameter transducer. The movement of the wire as a result of fluid flow variations inside an inductive pickup coil changes the self-inductance of the coil with the changes in flow rate. An improved inductance bridge network has been used to measure the self-inductance of the coil. It has been observed that the variation of the self-inductance of the pickup coil as well as the variation of the transducer and transmitter outputs with flow rate has a very good linearity and repeatability. The necessary theoretical equations, along with the experimental results, are reported in this paper. [ABSTRACT FROM AUTHOR]

Guiding magnetic field plays a very important role in the efficient operation of the relativistic backward-wave oscillator (RBWO). Generally, magnetic fields are made using solenoid coils extended behind the cathode region to get the desired magnetic field in the beam-microwave interaction region. Large diameter anodes are required to generate a required electron beam with low radial velocity. This paper presents a pulsed solenoid coil design in which the uniform magnetic field extends just up to the cathode and requires a much lesser volume in which the coil has to be kept and has a lower number of turns. This magnetic field coil setup has been tested for 18-A dc coil current to measure the magnetic field profile. A uniformity of 93.5% is achieved within 460 mm length. This coil setup was further tested with an RBWO setup at 550 kV, 7-kA electron beam parameters to generate 1-GW peak microwave power using a 0.55-T magnetic field at 3.28 GHz. [ABSTRACT FROM AUTHOR]

The central solenoid (CS) model coil (CSMC), which has a high stored energy, is developed to validate the CS manufacturing methods for the China Fusion Engineering Test Reactor (CFETR). The designed operation current of the model coil is 47.65 kA. The maximum rate of the magnetic field is 1.5 T/s. The stored energy of the model coil is 407.6 MJ. A set of verification test of the model coil will be conducted after manufacture, so a CSMC power supply, which generates the current for coil operation, and a quench protection, which could quickly release the stored energy, are required. The main circuit topology of power supply was designed according to the requirements of the testing current waveform. The current control was adopted, which controlled the actual output current provided by the power supply system to track any specified current reference of the model coil within acceptable precision. The design of the quench protection system for model coil was also described in this paper. [ABSTRACT FROM AUTHOR]

The ITER magnet system is made up of four main subsystems: 18 toroidal field (TF) coils, a six-module central solenoid coil, 6 poloidal field (PF) coils, and 18 correction coils (CCs). The Feeder system with its main busbar and correction coil busbar represents one of the main magnet components as well. All coils and busbars with different dimensions used cable-in-conduit conductors (CICCs). China needs to provide six different types of conductors. The ITER CICCs consist of a cable made of Nb3Sn or Nb-Ti strands inserted in a stainless steel tube (called jacket or conduit). Depending on the coil type, the jacket material is either made of a low carbon AISI 316LN (for TF coil) or AISI 316L grade stainless steels (for PF and CC coils, etc). Mechanical properties of base material need to be tested at room and/or cryogenic temperature under predefinedmechanical deformation and heat treatment conditions. This paper concerns mechanical tests on the jacket materials, including static tensile tests, fatigue crack growth rate, and fracture toughness tests. [ABSTRACT FROM AUTHOR]

The Muon Ionization Cooling Experiment located at Rutherford Appleton Laboratory in England utilizes a superconducting solenoid system for the muon cooling channel that also holds particle-tracking detectors and muon absorbers inside their bores. The solenoid system installation was completed in summer of 2015 and after commissioning the system it has been running successfully. This paper summarizes the commissioning results and operational experience with the magnets focusing on the performance of the two spectrometer solenoids built by the U.S. [ABSTRACT FROM AUTHOR]