Measurements and analysis of dynamic effects in the LARP model quadrupole HQ02b during rapid discharge

Journal Article · 31 May 2016 · IEEE Transactions on Applied Superconductivity

DOI: https://doi.org/10.1109/TASC.2016.2524584 · OSTI ID:1327419

Sorbi, Massimo ^[1]; Ambrosio, Giorgio ^[2]; Bajas, Hugo ^[3]; Chlachidze, Guram ^[2]; Marinozzi, Vittorio ^[1]; Mariotto, Samuele ^[1]; Sabbi, Gianluca ^[4]

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1. Univ. of Milano and INFN-LASA, Milan (Italy)
2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
3. European Organization for Nuclear Research (CERN), Geneva (Switzerland)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)

This paper presents the analysis of some quench tests addressed to study the dynamic effects in the 1-m-long 120-mm-aperture Nb₃Sn quadrupole magnet, i.e., HQ02b, designed, fabricated, and tested by the LHC Accelerator Research Program. The magnet has a short sample gradient of 205 T/m at 1.9 K and a peak field of 14.2 T. The test campaign has been performed at CERN in April 2014. In the specific tests, which were dedicated to the measurements of the dynamic inductance of the magnet during the rapid current discharge for a quench, the protection heaters were activated only in some windings, in order to obtain the measure of the resistive and inductive voltages separately. The analysis of the results confirms a very low value of the dynamic inductance at the beginning of the discharge, which later approaches the nominal value. Indications of dynamic inductance variation were already found from the analysis of current decay during quenches in the previous magnets HQ02a and HQ02a2; however, with this dedicated test of HQ02b, a quantitative measurement and assessment has been possible. An analytical model using interfilament coupling current influence for the inductance lowering has been implemented in the quench calculation code QLASA, and the comparison with experimental data is given. In conclusion, the agreement of the model with the experimental results is very good and allows predicting more accurately the critical parameters in quench analysis (MIITs, hot spot temperature) for the MQXF Nb3Sn quadrupoles, which will be installed in the High Luminosity LHC.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1327419
• Alternate ID(s): OSTI ID: 1454466
• Report Number(s): FERMILAB-PUB--16-395-TD; {1479355,"Journal ID: ISSN 1051-8223"}
• Journal Information: IEEE Transactions on Applied Superconductivity, Journal Name: IEEE Transactions on Applied Superconductivity Journal Issue: 4 Vol. 26; ISSN 1051-8223
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)Copyright Statement
• Country of Publication: United States
• Language: English