A methodology for the analysis of the three-dimensional mechanical behavior of a Nb3Sn superconducting accelerator magnet during a quench

J Ferradas Troitino,S Izquierdo,H Bajas,E Takala,G Vallone,B Castaldo,J V Lorenzo,M Guinchard,P Ferracin,C Senatore,L Bianchi,F Mangiarotti,J C Perez

doi:10.1088/1361-6668/ac0952

Abstract

The fast thermal and electromagnetic transients that occur in a superconducting magnet in case of a quench have the potential of generating large mechanical stresses both in the superconducting coils and in the magnet structure. While the investigation of such quench loads should generally be conducted to ensure a safe operation of the system, its importance is greatly enlarged in the case of high-field magnets based on strain sensitive superconductors. For these, a rigorous analysis of the magnet mechanics during a quench becomes critical. The scope of this work is hence to bring, for the first time, a detailed understanding of the three-dimensional mechanical behavior of a Nb3Sn accelerator magnet during a quench discharge. The study relies on the use of finite element models, where various multi-domain simulations are employed together to solve the coupled physics of the problem. Our analysis elaborates on the case study of the new MQXF quadrupole magnet, currently being developed for the high-luminosity upgrade of the LHC. Notably, we could find a very good agreement between the results of the simulation and experimental data from full-scale magnet tests. The validated model confirms the appearance of new peak stresses in the superconducting coils. An increase in the most relevant transverse coil stresses of 20–40 MPa with respect to the values after magnet cool-down has been found for the examined case.

Highlights

The generation of superconducting accelerator magnets will turn into a reality the ambitious objective of routinely producing magnetic field levels beyond 10 T for the interaction with particle beams [1,2,3,4]
A deeper look into the effect of the quench loads in conductor performance can be obtained by expanding the analysis using, for example, the proposal published in [96]. This manuscript presented the development of a methodology aimed at studying the three-dimensional mechanical behavior of a superconducting magnet during a quench
The analysis becomes necessary for the generation of accelerator magnets based on Nb3Sn, in order to guarantee the correct performance of the system and the absence of conductor degradation

Summary

Introduction

The generation of superconducting accelerator magnets will turn into a reality the ambitious objective of routinely producing magnetic field levels beyond 10 T for the interaction with particle beams [1,2,3,4] This pursuit of higher magnetic performances translates, into novel challenges for the magnet design. The unceasing increase in the conductor current densities, the growing magnet stored energies, and the presence of large electro-magnetic forces have pushed the boundaries of the magnet conception and its quench protection toward new limits For the latter case, we refer to a quench as the abnormal termination of the magnet operation that occurs when a part of a superconducting coil transits irredeemably to the resistive state [5,6,7,8]. -called quench protection systems are normally employed to safely discharge the magnet when a quench is detected, becoming an essential part of the design

Methods

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Discussion

Conclusion