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ST390 - Protecting a Full-Scale Nb3Sn Magnet with CLIQ, the New Coupling-Loss Induced Quench System

Protecting a Full-Scale Nb3Sn Magnet with CLIQ, the New Coupling-Loss Induced Quench System
 
E. Ravaioli, H. Bajas, V. I. Datskov, G. Kirby, H. H. J. ten Kate, A. Verweij
 
University of Twente, PO Box 217, 7500 AE Enschede,
The Netherlands – CERN, Meyrin, Swizterland
 
Abstract — A new protection system for superconducting magnets called CLIQ (Coupling Loss Induced Quench system, was recently developed at CERN. Recent tests on Nb-Ti coils showed that CLIQ is a valid, powerful and promising method for the protection of high field magnets. However, the protection of new generation high magnetic field Nb3Sn based superconducting accelerator magnets is even more challenging due to the much higher stored energy per unit volume and to the significantly larger enthalpy needed to initiate and propagate a normal zone in such coils. Now the CLIQ system is tested for the first time on a Nb3Sn magnet in the CERN magnet test facility in order to investigate its performance in practice thereby validating the method for this type of superconducting magnets as well. Measurement results of discharges at various current levels are presented and compared to discharges obtained by quenching the magnet using conventional quench heaters and an energy extraction system. Furthermore, a dedicated simulation model of the magnet is developed to reproduce the measured transients and simulate CLIQ discharges under varying operating parameters. Finally, the implementation of a CLIQ based protection system for full size Nb3Sn magnets is discussed. The advantages and drawbacks of using multiple CLIQ units on a single magnet as well as the simultaneous use of CLIQ and classical quench heaters are thoroughly discussed.
 
IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), October 2014.
ASC manuscript 1LOr2B-01 published online in IEEE Trans. Appl. Supercond. (IEEE XPLORE)
DOI 10.1109/TASC.2014.2364892, on October 24, 2014. 
1st Prize in Best Student Paper Contest,
Large Scale Appl.