The CLIQ Quench Protection System Applied to the 16 T FCC-hh Dipole Magnets

Marco Prioli,Barbara Caiffi,Clement Lorin,Bernhard Auchmann,Javier Munilla,Stefania Farinon,Alejandro M Fernandez,Arjan Verweij,Lorenzo Bortot,Tiina Salmi,Michel Segreti,Michal Maciejewski

doi:10.1109/tasc.2019.2930705

Abstract

Part of the Future Circular Collider (FCC-hh) study is dedicated to the development of the 16 Tesla ${\rm Nb_3Sn}$ superconducting dipole magnets. The design of the magnets was enabled by a cooperative effort of national research institutes, universities, and CERN. These actors tackled the problem from different sides, namely, the electromagnetic design, the mechanical design, the design of the quench protection systems, and the circuit design. The article deals with the design of the quench protection systems and provides solid motivations for the selection of the coupling-loss-induced quench (CLIQ) device as the baseline protection system for the FCC-hh main dipole magnets. The article shows that the design domains mentioned above are tightly interconnected and, therefore, the simulation of a quench event involves a complex multiphysics problem. The STEAM cosimulation framework, recently developed at CERN, is applied to address the complexity. The STEAM-SIGMA models are employed to simulate the CLIQ quench protection system applied to the FCC-hh dipole magnets. Dedicated CLIQ configurations are identified to protect the magnets in case of a quench. In addition, the possible implications of the CLIQ protection system on the mechanical design of the magnets are discussed. To this end, the article employs the co-simulation of different software platforms to calculate the mechanical stress during a quench. The results show that CLIQ does not produce additional stress.

Highlights

A 100 TeV, 100 km proton–proton circular collider is under study for the Future Circular Collider (FCC) project [1]
This article shows that the design of the coupling-loss-induced quench (CLIQ) quench protection system is mutually coupled with the other magnet designs steps and requires a dedicated multiphysics approach for its simulation
The STEAM cosimulation framework was applied to address the complexity of the problem

Summary

INTRODUCTION

A 100 TeV, 100 km proton–proton circular collider is under study for the Future Circular Collider (FCC) project [1]. The fourth aspect considered is the study of the layout of the circuit containing the FCC magnets and it is centralized This last aspect is discussed in the companion paper [8]. The aim of this article is to present the final CLIQ protection schemes and demonstrate that this technology can protect the cos-θ, block coil, and common coil magnets in case of a quench Another example of the coupling is the one between the electromagnetic design and the circuit design. Since the electrical circuit contains a large number of dipole magnets, the maximum voltage-to-ground depends on the adopted circuit layout This aspect is discussed in the companion paper [8]. According to the aforementioned EuroCirCol specifications [2], [3], the mechanical design criterion is a maximum stress in the coils of 200 MPa at cold

DIPOLE MAGNETS

Strategy

Results

Expected Uncertainty

MECHANICAL STRESS DURING QUENCH

CONCLUSION