Electromechanical behaviour of pulse-field magnets in field-reversed fusion neutron sources

Abstract Current fusion devices cannot provide sufficient neutron irradiation to evaluate long-term material damage. To address this gap, we propose a magnetic-confinement deuterium–deuterium fusion neutron source. A key component of this system is the compression magnet, designed to generate a central field that rises from 0 T to 7 T within 15 ms across a region exceeding 800 mm. In the structural design of pulsed magnets, transient simulations are often required but are computationally expensive, especially for large-aperture systems. Steady-state results are therefore frequently used as approximations, yet no quantitative criterion exists to judge their reliability. In this study, we develop a one-dimensional stress model and an electromechanical based finite element model to investigate vibration periods and transient peak stresses. The analysis shows that changes in excitation frequency have little influence on the vibration period. From this, we define the time T max , the point at which stress peaks under a step electromagnetic load, as a reference parameter. We propose that when the rise time of the operating electromagnetic load is more than ten times T max , steady-state simulations provide an accurate estimate of transient peak stress. This criterion is validated using a practical magnet case study, demonstrating its potential for broader applicability. The results offer a simple and general method to reduce computation time and accelerate the structural design of large-aperture pulsed magnets for fusion neutron sources.