Instrumentation and Quench Protection for LARP Nb₃Sn Magnets

H. Felice, G. Ambrosio, G. Chlachidze, P. Ferracin, R. Hafalia, R.C. Hannaford, J. Joseph, A. Lietzke, A. McInturff, J. Muratore, S. Prestemon, G.L. Sabbi, J. Schmalzle, P. Wanderer, X. Wang

Abstract—The US LHC Accelerator Research Program (LARP) is developing Nb₃Sn prototype quadrupoles for the LHC interaction region upgrades. Several magnets have been tested within this program and understanding of their behavior and performance is a primary goal. The instrumentation is consequently a key consideration, as is protection of the magnet during quenches. In all LARP magnets, the flexible circuits traces combine the instrumentation and the protection heaters. Their fabrication relies on printed circuit technology based on a laminate made of a 45-micron thick kapton sheet and a 25-micron thick foil of stainless steel. This paper reviews the protection heaters designs used in the TQ (Technology Quadrupole) and LR (Long Racetrack) series as well as the one used in LBNL HD2a high field dipole and presents the design of the traces for the Long Quadrupole (LQ), addressing challenges associated with the stored energy and the length of the magnet.

Index Terms— Superconducting magnets, Nb₃Sn, protection heaters, quench protection, instrumentation, LARP

Manuscript received 26 August 2008.
This work was supported in part by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, High Energy Physics Division, U.S. Department of Energy, under contract No. DE-AC02-05CH11231.
H.Felice, P. Ferracin, R. Hafalia, C.R. Hannaford, J. Joseph, A. Lietzke, S. Prestemon, G. L. Sabbi and X. Wang are with Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA (e-mail: HFelice@lbl.gov).
G. Ambrosio, G. Chlachidze, are with Fermilab National Accelerator Laboratory, Batatvia, IL 60510-0500 USA.
J. Muratore, J. Schmalzle and P. Wanderer are with Brookhaven National Laboratory, NY, USA A. McInturff is with Texas A&M, Texas

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