相关论文: Eddy currents in accelerator magnets

In this work we deal with the shape optimization of an electric machine considering time-dependent effects such as eddy currents. The considered electric machine is an interior permanent magnet synchronous machine and we minimize the…

In conducting ferromagnetic materials, a moving domain wall induces eddy currents in the sample which give rise to an effective retarding pressure on the domain wall. We show here that the pressure is not just proportional to the…

We develop an analytical model for describing the magnetization dynamics in ferromagnetic metal nanoparticles, which is based on the coupled system of the Landau-Lifshitz-Gilbert (LLG) and Maxwell equations. By solving Maxwell's equations…

A simple model of eddy currents in which current is computed solely from magnetic forces acting on electrons proves accessible to introductory students and gives a good qualitative account of eddy current forces. However, this model cannot…

We discuss the well-posedness of the 'transient eddy current' magneto-quasistatic approximation of Maxwell's initial value problem with bounded and measurable conductivity, with sources, on a domain. We prove existence and uniqueness of…

The impact of granular microstructure in permanent magnets on eddy current losses are investigated. A numerical homogenization procedure for electrical conductivity is defined. Then, an approximated simple analytical model for the…

An analytical method of calculating eddy current in a metallic spinning gyroscope in external magnetic field is presented. With reasonable assumptions, the problem is simplified from the time-dependent one governed by Maxwell equations to…

We investigate how controlling induced eddy currents in thin film ferromagnet-normal metal (FM/NM) structures can be used to tailor the local microwave (MW) fields in ferromagnetic resonance (FMR) experiments. The MW fields produced by eddy…

We present the mathematical theory and its numerical validation of a method tailored to include eddy-current effects only in a part of the domain. This results in a heterogeneous problem combining an eddy-current model in a subset of the…

An electromagnetic analysis is presented for experiments with strong permanent disc magnets. The analysis is based on the well known experiment that demonstrates the effect of circulating eddy currents by dropping a strong magnet through a…

The switching behaviour of electromagnets is determined by the inertia of the armature, the stiffness of the return spring and the magnetostatic forces between armature and yoke. For highly dynamic systems, hysteresis and eddy current…

New results for attenuation and damping of electromagnetic fields in rigid conducting media are derived under the conjugate influence of inertia due to charge carriers and displacement current. Inertial effects are described by a relaxation…

Magnetic braking is a long-established application of Lenz's law. A rigorous analysis of the laws governing this problem involves solving Maxwell's equations in a time-dependent situation. Approximate models have been developed to describe…

This course introduces conventional magnets used in particle accelerators, focusing on both normal-conducting copper coil magnets and permanent magnets (PMs). It covers magnet classification, design principles, material selection, and…

Eddy current shielding by a Faraday cage is an effective way to shield alternating-current (AC) magnetic fields in scientific instrumentation. In a strong static magnetic field, however, the eddy current in the conductive shield is subject…

This lecture note describes how to set up and what is behind a magnetodynamic field simulation for an accelerator magnet. The relevant formulation of Maxwell's equations is derived. The formulation is discretized in space by the…

We investigate the effect of eddy currents on ferromagnetic resonance (FMR) in ferromagnet-normal metal (FM/NM) bilayer structures. Eddy-current effects are usually neglected for NM layer thicknesses below the microwave (MW) skin depth…

The issue of justifying the eddy current approximation of Maxwell's equations is re-considered in the time-dependent setting. Convergence of the solution operators is shown in the sense of strong operator limits.

The intention of this course is to provide guidance and tools necessary to carry out an analytical design of a simple accelerator magnet. Basic concepts and magnet types will be explained as well as important aspects which should be…

Axial flux permanent magnet designs are compact and becoming an attractive design for electric vehicles as an auxiliary braking system. This work develops the design of an Axial Flux Permanent Magnet Eddy current brake for application on…