Design of a 200-MHz continuous-wave radio frequency quadrupole accelerator for boron neutron capture therapy

A high-intensity continuous-wave(CW) radio frequency quadrupole(RFQ) accelerator is designed for boron neutron capture therapy.The transmission efficiency of a 20-mA proton beam accelerated from 30 keV to 2.5 MeV can reach 98.7% at an operating frequency of 200 MHz.The beam dynamics have a good tolerance to errors.By comparing the high-frequency parameters of quadrilateral and octagonal RFQ cross sections,the quadrilateral structure of the four-vane cavity is selected owing to its multiple advantages,such as a smaller cross section at the same frequency and easy processing.In addition,tuners and undercuts are designed to tune the frequency of the cavity and achieve a flat electric field distribution along the cavity.In this paper,the beam dynamic simulation and electromagnetic design are presented in detail.

High-frequency structure design and RF stability analysis of a 4-vane radio frequency quadrupole with pi-mode stabilizer loops

Compact accelerator-based neutron source facilities are garnering attention and play an important and expanding role in material and engineering sciences,as well as in neutron science education and training.Neutrons are produced by bombarding a low-energy proton beam onto a beryllium or lithium target.In such an acceleratorbased neutron source,a radio frequency quadrupole(RFQ)is usually utilized to accelerate a high-intensity proton beam to a few MeV.This study mainly covers the highfrequency structure design optimizations of a 4-vane RFQ with pi-mode stabilizer loops(PISLs)and its RF stability analysis.A 176 MHz RFQ accelerator is designed to operate at a 10%duty factor and could accelerate an80 mA proton beam from 65 keV to 2.5 MeV within a length of 5.3 m.The adoption of PISLs ensures high RF stability,eases the operation of the accelerator,and implies less stringent alignment and machining tolerances.

Design of the poloidal field system for KTX

The design of the poloidal field （PF） system includes the ohmic heating field system and the equilibrium （EQ） field system, and is the basis for the design of a magnetic confinement fusion device. A coupling between the poloidal and plasma currents, especially the eddy current in the stabilizing shell, yields design difficulties. The effects of the eddy current in the stabilizing shell on the poloidal magnetic field also cannot be ignored. A new PF system design is thus proposed. By using a low-μ material （μ = 0.001, ε = 1） instead of a conductive shell, an electromagnetic model is established that can provide a continuous eddy current distribution on the conductive shell. In this model, a 3D time-domain problem with shells translates into a 2D magnetostatic problem, and the accuracy of the calculation is improved. Based on these current distributions, we design the PF system and analyze how the EQ coils and conductive shell affect the plasma EQ when the plasma ramps up. To meet the mainframe design requirements and achieve an efficient power-supply design, the position and connection of the poloidal coils are optimized further.

Electromagnetic design and dynamic analysis of large turbo-generator

Through a great deal calculation, the design and simulation analysis of stator parametric and rotor electromagnetic system of 1000MW turbo-generator are performed by using Ansoft Maxwell Rmxprt12.1 software. Besides. the basic parameters of the generator, the geometry dimensions of the stator and rotor, type and sizes of the slots, coils and windings parameters and the way of windings connection are determined. The finite element model of electromagnetic systems of generator stator and rotor was constructed by Ansoft Maxwe112D3D 12.1, and the transient electromagnetic characteristics of generator was analyzed and simulated. The 3D geometric models of turbo-generator were established respectively by using PROE software, and the dynamic finite element model of generator structure was built by ANSYS workbench 11.0. In addition, the dynamic characteristics of stator iron core, stator frame were calculated respectively. The simulation calculation has shown that the structural parameters, material parameters, and the electromagnetic characteristics parameters for large turbogenerator that are put forward by this paper should be optimal. and the design plan and method suggested by this paper should be feasible. The paper provides an effective solution for the development of larger turbo-generator than 1000 MW.

Optimization Design of Electromagnetic Nihility Nanoparticles

Nihility material is a medium whose relative permittivity and permeability tend to zero simultaneously. In this work, comparing with the scattering properties of perfect nihility nanoparticles （made from nihility material）, we provide an optimization design of electromagnetic nihility nanoparticles, which is a coated hybrid nanosphere constituted by commutative c-negative （ENG） and μ-negative （MNG） media. Compared to a single ENG or MNG nanosphere, it is found that the total and back scattering spectra of coated hybrid nanospheres are much closer to those of perfect nihility nanospheres. Moreover, it is observed that the scattered electromagnetic field distribution of coated hybrid nanospheres is identical to that of perfect nihility nanospheres. These results indicate that the combination of commutative ENG and MNG media can constitute a composite structure which gives the closest approximation of electromagnetic scattering of perfect nihility nanospheres in a wide frequency range.

Electromagnetic System Design and Visual Simulation

An electromagnet design system is developed using Visual C++ language and OpenGL technology to visualize parametric 3D model. The system consists of primary design, optimization design, dynamic and static characteristics, and visual simulation. All empirical parameters and curves used in design process are stored in database. Through human-computer interactions, an electromagnetic system can be designed conveniently with the results and characteristics curves displayed in graphic model. Using this system can greatly shorten the process of product design, and the results satisfy technical requirements.

Levitation force analysis of medium and low speed maglev vehicles

The rule of levitation force variation with different structure and electromagnetic parameters provides a basis for electromagnet design of electromagnetic suspension （EMS） medium and low speed maglev vehicles. In order to acquire accurate calculation results of levitation force, different calculation methods, including analytical method, 2D FEM （finite element method）, and 3D FEM, are applied to investigate the impact of various structural parameters, such as excitation current, air gap, lateral offset, and pole width, on levitation force. The analytical analysis is based on the classic mathematical model of levitation force between electromagnet and rail and performed with MATLAB. In the 2D and 3D FEMs, the numerical calculation of the levitation force is conducted with Ansoft by taking the magnetic saturation into account. In addition, the longitudinal end effect on the levitation force calculation is considered in the 3D FEM. The results show that the 3D FEM is the most accurate among the above three methods for calculating the levitation force, and the analytical method can only work for small current and/or large air gap conditions. A lateral- offset between vehicle and rail will reduce the levitation force; the levitation force descends sharply once the lateral offset exceeds the threshold, i.e., 8% of the pole width for U-shaped electromagnets. The maximum lift-to-weight ratio emerges when the pole width ratio of F type rail to electromagnet is 6：7. This may offer a reference for EMS maglev vehicle design and application.

Performance Evaluation of a 60kW IPM Motor for Medium Commercial EV Traction Application

This paper presented the design and performance analysis of a 60kW interior permanent-magnet(IPM)synchronous motor used as traction drive in a medium commercial electric vehicle(EV),according to the traction requirements of the electric vehicle under the rated operating conditions and overload conditions.The key dimensions were calculated on the basis of the permanent-magnet(PM)motor theory,and the 2D finite element method(FEM)simulation model of the IPM motor was built by using 2D Maxwell software.The influence geometric structures of the IPM motor including the PM dimensions and skewed PMs on electromagnetic torque were investigated,and the temperature distribution of the motor under rated operating condition and the condition of maximum speed were calculated.Finally,the simulation results of the IPM motor running in various operating modes were compared with the experimental results,which demonstrated that the designed IPM motor can match all requirements of the medium commercial electric vehicle driving applications.

Detailed Design of a High Speed Switched Reluctance Starter/Generator for More/All Electric Aircraft

The basic concepts and advantages of more/all electric aircraft （M/AEA） are briefly addressed. The combined starter/generator （CS/G） system is introduced as a key technology to enable M/AEA. Some important performance requirements for CS/G system are obtained. Based on these requirements, a high speed switched reluctance machine （SRM） is designed to operate as a starter/generator. The entire design process is mainly divided into two stages： electromagnetic design and thermal design. In electromagnetic design stage, the electromagnetic structure and dimensions of the machine and the number of phase winding turns per pole are obtained; the topology and main technical details of the converter are briefly introduced as well. In thermal design stage, a liquid-cooling system is designed based on the thermal analysis of the machine. In the end, the performances of the designed SRM are basically verified by simulation. To get high performances, the exciting angles are optimized in two different operating modes respectively, and the optimized performances in the motoring mode are given as well.

An Electromagnetic Perspective of Artificial Intelligence Neuromorphic Chips

The emergence of artificial intelligence has represented great potential in solving a wide range of complex problems.However,traditional general-purpose chips based on von Neumann architectures face the“memory wall”problem when applied in artificial intelligence applications.Based on the efficiency of the human brain,many intelligent neuromorphic chips have been proposed to emulate its working mechanism and neuron-synapse structure.With the emergence of spiking-based neuromorphic chips,the computation and energy efficiency of such devices could be enhanced by integrating a variety of features inspired by the biological brain.Aligning with the rapid development of neuromorphic chips,it is of great importance to quickly initiate the investigation of the electromagnetic interference and signal integrity issues related to neuromorphic chips for both CMOS-based and memristor-based artificial intelligence integrated circuits.Here,this paper provides a review of neuromorphic circuit design and algorithms in terms of electromagnetic issues and opportunities with a focus on signal integrity issues,modeling,and optimization.Moreover,the heterogeneous structures of neuromorphic circuits and other circuits,such as memory arrays and sensors using different integration technologies,are also reviewed,and locations where signal integrity might be compromised are discussed.Finally,we provide future trends in electromagnetic interference and signal integrity and outline prospects for upcoming neuromorphic devices.