Performance of the First Short Model 150-mm-Aperture Nb3Sn Quadrupole MQXFS for the High-Luminosity LHC Upgrade

The U.S. LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb3Sn magnets for the high-luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb₃Sn quadrupoles for the LHC interaction regions. These magnets will replace the present 70-mm-aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity up to 5 × 10³⁴ cm ^-2s^-1 or more. Over the past decade, LARP successfully fabricated and tested short and long models of 90 and 120-mm-aperture Nb3Sn quadrupoles. Recently, the first short model of 150-mm-diameter quadrupole MQXFS was built with coils fabricated both by LARP and CERN. The magnet performance was tested at Fermilab's vertical magnet test facility. This paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence, as well as protection heater studies.

I. Introduction

The MQXFS1 magnet is the first short model of a 150 mm aperture Nb₃Sn quadrupole developed by the US LHC Accelerator Research Program (LARP) and CERN in preparation for the High-Luminosity LHC upgrade [1]. The integrated luminosity will be increased by a factor of 10 beyond the LHC's design value within this upgrade. Among other components to be upgraded are the inner triplet (low-β) quadrupoles in the LHC interaction regions. Large aperture Nb₃Sn quadrupoles (MQXF) will replace the present 70 mm aperture NbTi magnets [2], [3].