Dynamic structural response of DEMO divertor under electromagnetic loading

• Published in: Fusion engineering and design Vol. 187; p. 113375
• Main Authors: Zhang, Kuo, Mantel, Nicolas, You, Jeong-Ha
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2023
• Subjects: Dynamic amplification factor; Fixation; Static/dynamic response; Static/dynamic response; Dynamic amplification factor; Fixation
• ISSN: 0920-3796
• DOI: 10.1016/j.fusengdes.2022.113375

•Comparison between analytical dynamic amplification factor (DAF) in steady state, and numerical DAF in transient phase under impact.•Study of influencing factors on eigen-frequencies.•Search for a DAF, which can amplify the stress/strain/displacement in static analysis to be over the values in dynamic analysis.•Comparison of DAF with various types of fixation, from very loosen- to firm-fixation. The divertor of a tokamak-type fusion reactor is subject to the potential risk of accidental plasma disruptions. This fast transient event produces strong and brief electromagnetic (EM) excitation loads exerting in the divertor in form of volume forces and moments. Moreover, the transient nature of the impact loads could cause a substantial dynamic amplification of the Lorentz forces and moments due to the interaction between the (transient) resonance and mass inertia. This dynamic amplification effect must be considered in the structural design of the divertor in addition to the static loads. One pragmatic approach to do this is to apply the notion of dynamic amplification factor (DAF) as a kind of a force multiplier coefficient in order to reflect the dynamic effect in a static stress analysis. To this end, the dynamic amplification factor needs to be determined for the given geometry of the components and the typical application modes of relevant impact loads. The key objective of this dynamic analysis is to identify the natural frequencies (eigen-frequency) and the deformation modes. The dynamic effect on the stress intensity in the critical regions is also examined. This study presents a unique insight into the structural dynamics induced by a plasma disruption and delivers a very useful design parameter for the force component of the load, namely, dynamic amplification factor which allows a straightforward way of considering the resonance response in a static structural analysis.