Browsing by Subject "Finite element method"

In the field of cryogenics and superconducting technology, the effect of eddy currents presents a significant challenge, as large inductive currents can affect the performance and stability of cryogenic components. In our work, we examine how the magnitude of eddy current effects varies with different samples when placed within a changing magnetic field. In high magnetic field applications, any deviation in the magnetic field induces currents within low-resistivity components, leading to eddy current heating and Lorentz forces. This thesis focuses on how to simulate the eddy current phenomena in an accurate way through methods of finite element analysis, utilizing the commercial software of COMSOL Multiphysics. To provide a comprehensive simulation of the effects of eddy currents, our work involves the coupling of three distinct physical fields: solid mechanics, heat transfer, and electromagnetic fields. To solve multiphysical problem in an efficient way, we explain different strategies on how the coupled fields can be solved in a simplified, but effective way. The simulation was examined for two different time scale scenarios: 1. Turning on the magnet, where the time scale of the phenomena is in the order of several hours, and 2. The more demanding scenario of the quench of a superconducting magnet, where the time scale is in the order of several seconds. We found that during the ramping of the magnet the electromagnetic heating of the sample can reach the scales of milliwatts, which is significant head load in a cryogenic setting. During magnet quench, we found that the Lorentz forces can reach up to scales of kilonewtons. The results indicate that the volume of the sample has significant impact to effects of eddy currents, but when considering the magnitude of the Lorentz force the length and spatial location of the sample has significant effect. Hence, it is crucial to pay attention to the appropriate design of the sample that is placed into the magnetic field.