Design for 500-kW WPT Coils Based on Coil Geometry Search Including Physical Dimensions

INTRODUCTION: Despite more than a decade of endovascular coil treatment, the effects of coils on cerebral aneurysm (CA) hemodynamics are still poorly understood. Coils present several challenges to in vivo and in vitro flow measurement techniques and previous in silico methods have suffered from large assumptions on coil geometry. Here we present the first fluid dynamic simulations of coiled CAs that consider the structure and deployment mechanics of embolic coils. We also investigate the influence of coil packing density, design, and configuration on CA fluid dynamics. Methods: Coil deployment was modeled using a novel finite element approach that realistically simulates coil dynamics during deployment. Two coil designs were investigated: helical and 3D. Coil design and material properties were matched to manufacturer specifications. Five deployment sequences of each coil design, at different microcatheter placements, were simulated in two idealized CA models with variable neck sizes. Blood flow was simulated using computational fluid dynamics. Simulated deployments and fluid dynamics were then compared to deployments of actual coils in identical physical CA models and in vitro particle image velocimetry flow measurements. Results: Simulated results closely matched in vitro data. Reductions in aneurysmal velocity magnitudes were largest for 3D coils and in a narrow-neck model. In that model, 3D coil deployments reduced average aneurysmal velocity magnitudes by a 51% - 69% range at packing densities less than 20% and by a 74% - 84% range at packing densities greater than 30%. Linear regression results showed reductions were strongly dependent on the spacing between coil loops within the aneurysm and packing density, with correlations of 0.6 and 0.7 respectively. Conclusion: Coil design and packing density may play equally important roles in determining CA hemodynamics. Results in an anatomical model will also be presented. The proposed virtual coiling approach represents a novel and effective method for realistically simulating coiled CAs, and is an important step towards clinical preoperative planning of coil treatment.

Magnetic coil design study is carried out, for the purpose of mitigating or suppressing the edge localized modes (ELMs) in a EU DEMO reference scenario. The coil design, including both the coil geometry and the coil current requirement, is based on criteria derived from the linear, full toroidal plasma response computed by the MARS-F code (Liu et al 2000 Phys. Plasma 7 3681). With a single midplane row of coils, a coil size covering about 30°–50° poloidal angle of the torus is found to be optimal for ELM control using the n > 2 resonant magnetic perturbation (RMP) field (n is the toroidal mode number). For off-midplane coils, the coils’ poloidal location, as well as the relative toroidal phase (coil phasing) between the upper and lower rows of coils, also sensitively affects the ELM control according to the specified criteria. Assuming that the optimal coil phasing can always be straightforwardly implemented, following a simple analytic model derived from toroidal computations, it is better to place the two off-midplane rows of coils near the midplane, in order to maximize the resonant field amplitude and to have larger effects on ELMs. With the same coil current, the ex-vessel coils can be made as effective as the in-vessel coils, at the expense of increasing the ex-vessel coils’ size. This is however possible only for low-n (n = 1–3) RMP fields. With these low-n fields, and assuming 300 kAt maximal coil current, the computed plasma displacement near the X-point can meet the 10 mm level, which we use as the conservative indicator for achieving ELM mitigation in EU DEMO. The risk of partial control coil failure in EU DEMO is also assessed based on toroidal modeling, indicating that the large n = 1 sideband due to coil failure may need to be corrected, if the nominal n > 1 coil configurations are used for ELM control in EU DEMO.

A well-designed polarimeter is integral to the realization of the highly sensitive atomic magnetometer. Amongst various detection schemes, optical polarimetry based on Faraday modulator is most commonly used owing to its angular sensitivity at low-frequency range. The multilayered solenoid coil is the key component of Faraday effect based optical detection system. This paper primarily deals with design and analysis of multilayered coil of Faraday modulator. All deterministic parameters that affect the optimum design have been identified and analyzed. Mathematical expressions have been obtained for axial field homogeneity; modulation depth and power dissipation manifesting direct dependence on coil geometry. The design parameters of the coil are optimized with respect to axial magnetic field homogeneity over region of interest and reduced power losses with suitable geometric construction. The influence of different geometrical and electromagnetic parameters on optimum design has been highlighted and guidelines for design procedure are given. Theoretical results have been compared with simulation and experimental results. The mathematical formulation could be implemented in a computer program for recurrence design and to assist the realization of an optimized design of Faraday modulator coil.

A simulation study was initiated to investigate whether or not a marine full azimuth acquisition geometry improves the image of the subsurface at Heidrun. Full azimuth shot data was modelled with finite difference and one-way wave equation modelling, and images obtained from full, wide, and narrow azimuth survey geometries were compared with each other. The study shows that a full azimuth geometry leads to better suppression of noise, less migration artefacts, more consistent amplitudes along horizons, and sharper fault planes than a narrow azimuth design. Attenuation of multiple energy is present, but less than expected. The improvements in image quality can be obtained with a realistic 4-vessel wide azimuth design and a coil geometry, but the coil geometry has a smaller acquisition footprint in the shallower part. Based on the modelling results, a field trial with coil design was carried out at Heidrun.

Magnetic stimulation of peripheral nerves is evoked by electric field gradients caused by high-intensity, pulsed magnetic fields created from a coil. Currents required for stimulation are very high, therefore devices are large, expensive, and often too complex for many applications like rehabilitation therapy. For repetitive stimulation, coil heating due to power loss poses a further limitation. The geometry of the magnetic coil determines field depth and focality, making it the most important factor that determines the current required for neuronal excitation. However, the comparison between different coil geometries is difficult and depends on the specific application. Especially the distance between nerve and coil plays a crucial role. In this investigation, the electric field distribution of 14 different coil geometries was calculated for a typical peripheral nerve stimulation with a 27 mm distance between axon and coil. Coil parameters like field strength and focality were determined with electromagnetic field simulations. In a second analysis, the activating function along the axon was calculated, which quantifies the efficiency of neuronal stimulation. Moreover, coil designs were evaluated concerning power efficacy based on ohmic losses. Our results indicate that power efficacy of magnetic neurostimulation can be improved significantly by up to 40% with optimized coil designs.

In the SAE J2954 standard for stationary wireless charging of electric vehicles, two different coil geometries are proposed: The circular (C) and the double-D (DD) coil system. In the future, electric vehicles are expected to be equipped with the vehicle assembly (VA) coil geometry as proposed in the standard. This can be used as a design criterion for an electrified road, where the installed primary coils have to be compatible to the vehicle coil. In this paper, the two SAE systems are compared to each other regarding the coupling factor stability with a compatible primary side for dynamic wireless charging, i. e., charging while in motion. Therefore, two coil designs have been built up in laboratory, each consisting of three identical primary air coil pads compatible with the corresponding SAE secondary side. The results indicate that the coupling factor for the double-D coil system shows lesser variation along the path than for the circular coil system, but the absolute coupling factor is greater for the circular coil system.

An Inductive Charging System use an electromagnetic field to transfer energy between two galvanic separated objects. To ensure the energy transfer there are many possibilities to build up the coil geometry. The new coil geometry presented in this paper is based on a Quadrupole coil design which main advantage is the higher power density while power transfer. The Quadrupole itself is a configuration of superposition of two bipolar windings, orthogonal to each other. In addition to the Quadrupole coil there will be added another magnetization winding in parallel. Due to that, an additional degree of freedom to adjust the current will be outcome. Through the so-called magnetization winding it is possible to adjust the reactive current, while it is feasible to adjust the active current via the link winding, separately. This phenomenon will be disused in the later paper while the current design will be compared to common coil designs especially the series resonance topology. A numerical approach is introduced to ensure design criteria. In addition, a validation of the result is presented via FEM simulation and hardware measurement.

Wireless power transfer (WPT) systems for Electric Vehicles (EVs) are designed to meet specifications such as stray field, power transfer, efficiency, and ground clearance. Typical design approaches include iterative analysis of predetermined coil geometries to identify candidates that meet these constraints. This work instead directly generates WPT coil shapes and magnetic fields to meet specifications and constraints through the optimization of Fourier basis function coefficients. The proposed Fourier Analysis Method (FAM) applies to arbitrary planar coil geometries and does not rely on iterative finite-element analysis (FEA) simulations. This flexibility allows for rapid design evaluation across a larger range of coil geometries and design specifications. A prototype coil is built to compare FAM outputs to experimental measurements and FEA simulations. The FAM is then used to illustrate the tradeoff of coil current and stray field for a given power level showing that the method is capable of generating optimized coil shapes to meet arbitrary field constraints.

Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique investigated for the treatment of various neuropsychiatric disorders such as major depressive disorder and obsessive-compulsive disorder. Coil design and analysis has been a popular topic in TMS studies, primarily as the coil geometry significantly affects the induced electric field ( $E$ -field) distribution. In this work, we compare the distribution of the induced $E$ -field of 16 different TMS coils by finite element analysis. The coils are positioned at two head locations: the vertex and the dorsolateral prefrontal cortex (DLPFC). Due to the coil geometry, only nine of the 16 coils are positioned at the DLPFC. Notably, the authors use 50 heterogeneous head models derived from MRI scans of healthy patients in this analysis. As a result, the sensitivity of the $E$ -field intensity and focality to anatomical variations is investigated. The maximum $E$ -field intensity induced in the brain ( $E$ -Max brain), and the volume in the brain exposed to the $E$ -field with at least half the $E$ -Max ( $V$ -Half) were metrics used to assess the intensity and focality of the induced $E$ -field. It was observed that some of the coils induced high $E$ -field intensity and were highly sensitive to anatomical variations. Other coils exhibited high focality and lower sensitivity to anatomical variations at the same time. For the coils positioned at the DLPFC, less variability was observed when compared to the vertex location. This study provides an understanding of the effect of coil geometry and anatomical variation on the induced $E$ -field during TMS.

Recent progress in 3D tokamak modeling is now leveraged to create a conceptual design of new external 3D field coils for the DIII-D tokamak. In this work generalized perturbed equilibrium code is used to determine optimally efficient spectrum for driving total, core, and edge neoclassical toroidal viscosity torque. These fundamental modes of 3D control are shown to have consistent outboard structures across a wide variety of plasma scenarios and machines. Given these target spectra, the currents and 3D geometry of multiple coils can be optimized to increase efficient drive for the physics of interest without undesired secondary effects. Here, this nonlinear optimization is demonstrated using the flexible optimized coils using space-curves code. The optimized coils are individually distorted in space, creating toroidal ‘arrays’ containing a variety of shapes that often wrap around a significant poloidal extent of the machine. Importantly, efficient coupling can be maintained even when enforcing large distances between coils and the plasma during the geometric optimization of coil designs. The physics-driven optimization presented here thus provides a practical path to utilizing coils built on the exterior of the vacuum chamber in future reactors to obtain the powerful 3D field benefits demonstrated on current machines with close, internal coils.

We propose a novel flexible and entirely stretchable radiofrequency coil for magnetic resonance imaging. This coil design aims at increasing patient comfort during imaging while maintaining or improving image quality. Conductive silver-coated thread was zigzag stitched onto stretchable athletic fabric to create a single-loop receive coil. The stitched coil was mounted in draped and stretched fashions and compared to a coil fabricated on flexible printed circuit board. Match/tune circuits, detuning circuits, and baluns were incorporated into the final setup for bench measurements and imaging on a 3T MR scanner. A fast spin echo sequence was used to obtain images for comparison. The fabricated coil presents multi-directional stretchability and flexibility while maintaining conductivity and stitch integrity. SNR calculations show that this stretchable coil design is comparable to a flexible, standard PCB coil with a 13-30% decrease in SNR depending on stretch degree and direction. In vivo human wrist images were obtained using the stitched coil. Despite the reduction in SNR for this combination of materials, there is a reduced percentage of SNR drop as compared to existing stretch coil designs. These imaging results and calculations support further experimentation into more complex coil geometries. This coil is uniquely stretchable in all directions, allowing for joint imaging at various degrees of flexion, while offering the closest proximity of placement to the skin. The materials provide a similar level of comfort to athletic wear and could be incorporated into coils for a variety of anatomies.

A new type of high-frequency RF surface coil was developed for in vivo proton or other nuclei NMR applications at 7T. This is a purely distributed-element and transmission line design. The coil consists of a thin strip conductor (copper or silver) and a ground plane separated by a low-loss dielectric material with a thickness (H). Due to its specific semi-open transmission line structure, substantial electromagnetic energy is stored in the dielectric material between the thin conductor and the ground plane, which results in a reduced radiation loss and a reduced perturbation of sample loading to the RF coil compared to conventional surface coils. The coil is characterized by a high Q factor, no RF shielding, small physical coil size, lower cost, and easy fabrication. A brief theoretical description of the microstrip RF coil is given that can be used to guide the coil designs. A set of gradient-recalled echo images were acquired by using the single- and two-turn microstrip RF surface coils from both phantom and human brain at 7T, which show good penetration and sensitivity. The two-turn coil design significantly improves the B1 symmetry as predicted by the microstrip theory. The optimum H for microstrip surface coils is approximately 7 mm. This coil geometry yields a B1 penetration similar to that of conventional surface coils. SNR comparison was made between the microstrip coil and conventional surface coils with and without RF shielding. The results reveal that the novel surface coil design based on the microstrip concept makes very high-field MRI/MRS more convenient and efficient in research and future clinics.

Magnetic stimulation can activate excitable tissues noninvasively. However, this method requires high energy to operate and can produce equipment heat that leads to inefficient stimulation. In this study, a comprehensive optimization of efficiency for magnetic stimulation has been conducted. A total of 16 781 coil designs were tested in order to determine the optimal coil geometry and inductance for neural excitation. Induced electric fields were calculated to find the optimal stimulation site (OSS) of a given coil. The threshold energy of a magnetic pulse for neural excitation was then calculated based on the transmembrane responses of a nerve model. Simulation results show that there exists an optimal inductance, as a consequence of an optimal pulse duration, corresponding to a minimum threshold energy. A longer pulse width is required to obtain the maximum efficiency for axons with slower membrane dynamics, a longer coil-to-fiber distance, and greater values of resistance (R) and capacitance (C) of the resistance-inductance-capacitance circuit. The optimal geometry features a minimum coil height, suggesting a flat coil design for optimal efficiency. The dimension of the optimal coil design increases with the coil-to-fiber distance. Moreover, the cloverleaf design achieves the highest efficiency for infinitely long fibers whereas the butterfly design is optimal for terminating or bending fibers.

The inductive power transfer (IPT) has contributed to the fast growth of the electric vehicle (EV) market. The technology to recharge the EV battery has attracted the attention of many researchers and car manufacturers in developing green transportation. In IPT charging system, the coil design is indispensable in enhancing the EV battery charging process performance. This paper starts by describing the two charging techniques; static charging and dynamic charging before further presents the IPT system descriptions. Afterwards, this paper describes a brief review of coil designs which discusses the critical factors that affect the power transmission efficiency (PTE) including their basic designs, design concepts and features merits. The discussions on the basic coil designs for IPT are of the circular spiral coil (CSC), square coil (SC), rectangular coil (RC), and double-D coil (DDC). Furthermore, the significant advantages and limitations of each research on different geometries are analyzed and discussed in this paper. Finally, this paper evaluates some essential aspects that influence the coil geometry designs in practical.

Nonplanar mold surface heating using external inductive coil and magnetic shielding materials