Search

A three-dimensional analysis of the leakage magnetic field in a transformer with beveled edges in a magnetic shunt is described. This paper contains a mathematical description of the finite element method used in performing numerical calculations. Formulas allowing to determine the differential and integral parameters of the magnetic field were presented. Magnetic flux density distributions and the points with high values were determined in the shell-type core and movable shunt sub-areas. For different positions of the magnetic shunt, the short-circuit transformer reactance was calculated as the integral parameter of the above-mentioned magnetic field analysis. Their amounts for the extreme positions of the shunt were given, as well. The movable magnetic shunt geometry impact on the short-circuit current value is given. In order to validate the calculation results, the research included some point measurements of magnetic flux density vectors and the winding reactances as well, and good compliance with the simulation data has been obtained. Thus, this analysis can also be applied to other objects with movable shunts in their magnetic systems. [ABSTRACT FROM AUTHOR]

Research on the value and nature of physical quantities allows for a detailed understanding of the conditions in the studied area, and the quality and precision of the final conclusions depend on the accuracy of the measurements. In order to increase the accuracy of measurements, the measurement infrastructure and unmanned vehicles used during the observation should introduce the lowest possible disturbance–they should be minimized in terms of the magnetic field. This article presents a solution based on the infrastructure model and the development of a method using polynomial regression to study the magnetic field in three dimensions (3D-longitudinal X, transverse Y, and vertical Z components). The test stand consists of an Arduino Mega microcontroller, a rotary table driven and controlled by a stepper motor, a touch display whose task is to control the magnetic field measurement parameters and display 3D data, and proprietary software made in the Python programming language. The structural elements of the stand model were produced by an additive method using a 3D printer. The presented solution belongs to the group of modern technological solutions known as the technology of low object detection (stealth technology or low observable technology). [ABSTRACT FROM AUTHOR]

We report the observation of improved confinement discharge in a magnetic braking experiment in the KSTAR tokamak. The improved confinement is achieved with reduced toroidal plasma rotation by non-axisymmetric magnetic field induced toroidal rotation braking along with significant reduction of edge localized modes (ELMs). Modifications in multi-channel transport raise fast ion slowing-down time and improve neutral beam deposition, leading to improved fast ion confinement. We show that modifications of radial electric field and E × B shear flow by magnetic braking provoke an enhanced pedestal to sustain thermal confinement against degradation in the typical 3D field experiment.

Neodymium magnets were independently discovered in 1984 by General Motors and Sumitomo. Today, they are the strongest type of permanent magnets commercially available. They are the most widely used industrial magnets with many applications, including in hard disk drives, cordless tools and magnetic fasteners. We use a vector potential approach, rather than the more usual magnetic potential approach, to derive the three-dimensional (3D) magnetic field for a neodymium magnet, assuming an idealized block geometry and uniform magnetization. For each field or observation point, the 3D solution involves 24 nondimensional quantities, arising from the eight vertex positions of the magnet and the three components of the magnetic field. The only unknown in the model is the value of magnetization, with all other model quantities defined in terms of field position and magnet location. The longitudinal magnetic field component in the direction of magnetization is bounded everywhere, but discontinuous across the magnet faces parallel to the magnetization direction. The transverse magnetic fields are logarithmically unbounded on approaching a vertex of the magnet. [ABSTRACT FROM AUTHOR]

• Design a multi-frequency, three-dimensional (3D) ACFM detection system to obtain rich information on rail surface defects. • Design an expandable phase-locked amplifier module and an adjustable multi-frequency signal source module, which realize synchronous demodulation of multi-frequency and multi-channel detection signals. • Comprehensive evaluation and classification of different surface defects. High load wheel-rail friction leads to surface defects on the rail, which requires an accuracy non-destructive testing (NDT) technology to prevent rail fracture and even major safety accidents. Alternating current field measurement (ACFM) has attracted attention due to its high detection precision and low sensitivity of lift-off and velocity effects. The paper proposes a multi-frequency, three-dimensional (3D) ACFM detection system that can obtain abundant detection information for multi-frequency comprehensive evaluation to improve detection accuracy. The system mainly includes an expandable phase-locked amplifier module and an adjustable multi-frequency signal source module, which provides a hardware IQ demodulation acceleration platform for multi-frequency and multi-channel ACFM detection to obtain enough defect signals for analysis. Analysis of the speed effect indicates that increasing the excitation frequency can improve the stability of the detection signal. We design a quantitative evaluation model for defects with a depth of 2–8 mm and surface angle between 30° and 75°. [ABSTRACT FROM AUTHOR]

Aiming at the performance of giant magnetostrictive transducer and its magnetic field environment, the magnetic field intensity, magnetic leakage and magnetic field uniformity of giant magnetostrictive material(GMM) rod of giant magnetostrictive transducer were studied. Based on GMM, a double-coil transducer was designed. On the basis of analyzing the characteristics of GMM and the working principle of giant magnetostrictive transducer, the design principles of increasing the magnetic field intensity of GMM rod, reducing magnetic leakage and improving the uniformity of magnetic field were put forward. The magnetic field strength in the direction of the rod axis was used as the evaluation standard. The three-dimensional magnetic field simulation of the double-coil giant magnetostrictive transducer was performed by COMSOL Multiphysic. The influence of the structure parameters of the upper and lower magnets and the magnetic conduction loop on the mean value and the uniformity of the magnetic field of the giant magnetostrictive transducer was analyzed. The results indicate that with the increase of the radius of the magnetizer, the uniformity of the magnetic field of the GMM rod increases first and then the amplitude increases slowly. The average value of the magnetic field first changes and then decreases sharply. With the increase of the relative permeability of the magnetic circuit, the magnetic field strength of the GMM rod significantly increased, when the relative magnetic permeability reaches 1 500, the average value of the magnetic field strength tends to be balanced. After optimization, the uniformity of the magnetic field is increased from 59.7% to 90.5%, an increase of 30.8%. [ABSTRACT FROM AUTHOR]

Abstract The electron injector system for a future mid-infrared free-electron laser (MIR FEL) and coherent terahertz (THz) radiation source at the Plasma and Beam Physics (PBP) Research Facility of Chiang Mai University (CMU) in Thailand will consists mainly of a thermionic cathode radio-frequency (RF) electron gun, an alpha magnet, a traveling-wave linear accelerator (linac) structure and two magnetic bunch compressor systems. The detailed study of all components in the injector system is very important for generation of high quality electron beam and radiation. This paper focuses on the alpha magnet, which is used as a magnetic bunch compressor and an energy filter before the beam being accelerated in a post-acceleration linac structure. We report its characteristics and the electron beam dynamics in its three-dimensional (3D) magnetic field distribution that was simulated with the program CST EM Studio 2016. The simulated alpha magnet's fields are comparable with the measurement data. The beam dynamic simulations in 3D magnetic field were performed by using programs ASTRA and ELEGANT. The simulation results allow us to investigate the influence of the fringe field, the vertical focusing and the space charge effect in the alpha magnet. This is significantly important for electron beam manipulation in the injector system. The study outputs reveal that the proper injection angle in the practical beam operation to compensate the fringe field effect should be 42 ∘ that is 1.29 ∘ larger than the ideal injection angle. We also found that the ratio of the vertical focal length to the total path length in the alpha magnet is 0.544, which is independent on the magnetic field gradient. Moreover, the space charge force in the electron bunch leads to the rotation of transverse phase spaces while the beam traverses in the alpha magnet's field. This effect has considerably small influence on the longitudinal phase space, especially for the beam with a bunch charge not exceeding 0.2 nC. [ABSTRACT FROM AUTHOR]

The present work provides a detailed description on quantitative 3D magnetic field reconstruction using a scanning magnetoresistance microscopy setup incorporating a 19.5 μm × 2.5 μm magnetoresistive sensor. Therefore, making use of a rotation stage, 11 nm thick ferromagnetic CoFe elements with 20 μm × 5 μm planar size were measured along different sensor axes and converted into cartesian coordinate magnetic field components by use of the analytical coordinate transform equations. The reconstruction steps were followed and validated by numerical simulations based on a field averaging model caused by a non-negligible sensor volume. Detailed in-plane magnetic component reconstruction with ability to reconstruct sub-micrometer features is achieved. A discussion on the limiting factors for optimal resolution is presented. [ABSTRACT FROM AUTHOR]

The present paper deals with 3D magnetic field analysis of conducting current contours. The magnetic field and forces were calculated analytically and by FEM applying the Comsol Multiphysics package. Forces were calculated by the Maxwell stress tensor and by volume force density. Numerical results for real and ideal contours with the same linear dimensions are discussed. Comparison between analytical and numerical data shows satisfactory agreement.

The superior performance of a novel deflection-type multi-DOF actuator is introduced briefly in this paper, three kinds of permanent magnetic rotor magnetization modes and schemes for a new PM deflection-type multi-DOF motors have been put forward. Static magnetic flux density modulus value calculation and static magnetic field analysis of every kind of permanent magnet magnetization modes and key structure parameters are implemented, and then the detailed distribution features of the rotor in permanent magnet deflection-type multi-DOF motor are simulated under the circumstance of 3D finite element software. Finally some disciplines of NdFeB rotor are concluded and analyzed. The results provide the references for the structure design of such kind of actuators or motors. [ABSTRACT FROM AUTHOR]

The superior performance of PM spherical Multi-DOF motors is introduced briefly in this paper, four kinds of permanent magnetic rotor design schemes for a new PM spherical Multi-DOF motors have been put forward. Static magnetic flux density modulus value calculation and static magnetic field analysis of every kind of permanent magnet structure are implemented, and then the torque features of permanent magnetic rotor structures in permanent magnet spherical multi-DOF motor are simulated under the circumstance of 3D finite element software. Finally the five cylinder structure of NdFeB rotor is manufactured instead of spherical structures. The experiment results demonstrate the effectiveness of the designed structure. [ABSTRACT FROM AUTHOR]