Coupling Effect between Equilibrium Field and Heating Field and Modification of the Power Supply System on SUNIST Spherical Tokamak

Strong inductive coupling between the heating field and equilibrium field is confirmed to be responsible for the poor plasma equilibrium in initial discharges on the SUNIST spherical tokamak. A modification project for the power supply system of equilibrium field coils is successfully performed to increase the duration time of plasma current flattop from much less than 1ms to about 2 ms.

RIGOROUS PROOF FOR CHARACTERISTICS OF PRACTICABLE MAGNETIC POTENTIOMETERS AND THEIR APPLICATION

The characters of practicable magnetic potentiometers have not been rigorously proved. This paper deduced a mathematical description of mutual inductance of the cylindricalmagneticpotentiometerwithfinite turns crosssection and verifies that M is independent of the position with respect to the primary circuit and is unaffected by stray fields of current not linked with them. Using these features, a novel device is designed to measure ACcurrent of the measuring range 0~4 000 A. The experimental result shows the measuring error is less than 1%.The device holds various advantages: such as the fixed number of turns of the primary winding, low cost, small size and weight. This paper pointed out that if the device is used to measure the nonsinusoidal signal, an integrator can increase the accuracy.

Magnetic transition of ferromagnetic material at high pressure using a novel system

A system for the investigation of the magnetic properties of materials under high pressure is fabricated based on diamond anvil cell （DAC） technology. The system is designed with an improved coil arranged around the diamond of a non-magnetic DAC. Using this system, the magnetic transition of ferromagnetic （Fe） sample under increasing pressure can be observed. We successfully obtain the evolution of magnetic properties as a function of applied pressure reaching 26.9 GPa in the Fe sample. A magnetic transition is observed at approximately 13 GPa, which is consistent with the theoretical prediction.

Dynamics modeling and electromechanical coupling characteristics analysis of cage induction motors

Induction motors, as typical electromechanical energy conversion devices, have received limited attention in previous studies on electromechanical coupling vibrations, precise modeling, and the use of electromechanical coupling effects for fault diagnosis and condition assessment in motor drive systems. This study proposes a comprehensive model of cage induction motors that integrates the multiple coupled circuit model with a rotor-bearing dynamics model. The model accounts for the linear increase in the magnetomotive force across the slot and incorporates the skidding characteristics of bearings in the rotor-bearing system. By calculating the time-varying mutual inductance parameters based on the air-gap distribution in the vibration environment, the electromechanical coupling vibration of the cage motor is investigated. Furthermore, this study examines the electromechanical coupling vibration characteristics influenced by various factors, including bearing clearances, radial loads, and the vertical excitation frequencies of the stators. The results show that the proposed model improves the excitation inputs for the electrical and mechanical systems of the motor compared with conventional models. Increased bearing clearance and radial load affect the current and torque similarly but have opposite effects on the slip ratio. This study provides a deeper understanding of electromechanical coupling mechanisms and facilitates the use of such phenomena for fault diagnosis and condition assessment in motor-driven systems.

Coupling analysis of transcutaneous energy transfer coils with planar sandwich structure for a novel artificial anal sphincter

This paper presents a set of analytical expressions used to determine the coupling coefficient between primary and secondary Litz-wire planar coils used in a transcutaneous energy transfer(TET) system. A TET system has been designed to power a novel elastic scaling artificial anal sphincter system(ES-AASS) for treating severe fecal incontinence(FI), a condition that would benefit from an optimized TET. Expressions that describe the geometrical dimension dependence of self- and mutual inductances of planar coils on a ferrite substrate are provided. The effects of ferrite substrate conductivity, relative permeability, and geometrical dimensions are also considered. To verify these expressions, mutual coupling between planar coils is computed by 3D finite element analysis(FEA), and the proposed expressions show good agreement with numerical results. Different types of planar coils are fabricated with or without ferrite substrate. Measured results for each of the cases are compared with theoretical predictions and FEA solutions. The theoretical results and FEA results are in good agreement with the experimental data.

An efficient technique to retrieve information from a damaged near-field communication tag

Purpose-The purpose of this paper is to discuss a technique of restoring data from a broken/damaged near-field communication(NFC)tag whose coil is damaged and seems unrecoverable.Design/methodology/approach-This paper discusses a method to restore data from damaged NFC tags by designing a coil that matches the technical specification of NFC for restoring information.In this paper,an NFC tag with a broken antenna coil and its operational NFC chip is used for restoring data by making an external loop antenna for the same chip.Findings-If the NFC tag is damaged,the information stored on the tag can be lost and can cause serious inconvenience.This research provides an excellent mechanism for retrieving all the information accurately from a damaged NFC tag provided the NFC chip is not damaged.Research limitations/implications-One of the major limitations of this research is that the NFC chip remains intact without any damages.Data can only be recoverable if just the antenna of the NFC tag is damaged;any damage to the NFC chip would make it impossible for the data to be recoverable.Practical implications-The research is carried out with limited resources in an academic institute and hence cannot be compared to antenna designs of the industry.Furthermore,industry vendors are using aluminum to design the coil;however,in this study a copper coil is used for coil design since it is far less expensive than aluminum coil.Originality/value-NFC is a rather new short-range wireless technology and not much work is done in this field as far as antenna study is concerned.This study brings a technique to design a coil antenna for a damaged NFC tag to retrieve all the information without losing even a single bit of sensitive information.

Research on Electromagnetic Characteristics of the Inductively Coupled Coil for Small Animal MR Imaging

The inductively coupled coils principally consist of two coils with no physical connection in between.A major problem is a mutual inductance between the two coils,which caused the frequency response peaks splitting.In this study,it was found that the position of the splitting of the peaks is not only related to the coupling coefficient(k)but also related to the quality factor(Q)of the coil.Based on this research,we construct a coupled coil for use in a 1.5T clinical MR scanner,this coil,comprising two semicircular coils fixed symmetrically around on a cylinde frame,was designed and constructed.The3-inch surface coil supplied by the MR scanner was used to compare imaging performance with the coupled coil.A water phantom was used for the signal-to-noise ratio(SNR)measurements.A total of 52 male Sprague-Dawley rats and 16 male BALB/C nude mice were scanned in this study for feasibility evaluation.