Mechanical Qualification of the Support Structure for MQXF, the Nb₃Sn Low- <inline-formula> <tex-math notation="LaTeX">$\beta$</tex-math> </inline-formula> Quadrupole for the High Luminosity LHC

Abstract

Abstract-Within the scope of the High Luminosity LHC project, the collaboration between CERN and U.S. LARP is developing new low-β quadrupoles using the Nb 3 Sn superconducting technology for the upgrade of the LHC interaction regions. The magnet support structure of the first short model was designed and two units were fabricated and tested at CERN and at LBNL. The structure provides the preload to the collars-coils subassembly by an arrangement of outer aluminum shells pre-tensioned with water-pressurized bladders. For the mechanical qualification of the structure and the assembly procedure, superconducting coils were replaced with solid aluminum "dummy coils", the structure was preloaded at room temperature, and then cooled-down to 77 K. Mechanical behavior of the magnet structure was monitored with the use of strain gauges installed on the aluminum shells, the dummy coils and the axial preload system. This paper reports on the outcome of the assembly and the cool-down tests with dummy coils, which were performed at CERN and at LBNL, and presents the strain gauge measurements compared to the 3D finite element model predictions.

Assembly Tests of the First Nb3Sn Low-Beta Quadrupole Short Model for the Hi-Lumi LHC

“…In the past months, mechanical models of the short magnets using aluminum false coils have been assembled and cooled down to validate the support structure both at CERN and within LARP. Results showing excellent agreement between strain gauges data and analysis are reported in [3]. Here, we focus on the first mechanical assembly of the magnet using four real coils and we show how the assembly process is a direct application of the experience gained with LQ and HQ [4].…”

“…Key components of this upgrade are the Interaction region Low- Quadrupoles Q1, Q2 and Q3 [1]. The 150 mm aperture Nb 3 Sn magnets are developed in collaboration between the US-LARP (LHC Accelerator Research Program) and CERN. In this framework, the US is in charge of the ten Q1 and Q3 cold masses; each of them being made out of two 4.9 m long magnets called MQXFA.…”

Summary of Test Results of MQXFS1—The First Short Model 150 mm Aperture Nb3Sn Quadrupole for the High-Luminosity LHC Upgrade

“…Measurements from both were later compared to a 3D finite element analysis (FEA) estimates for the magnet and were used in mechanical validation and monitoring during the tests. Detailed mechanical analysis of the support structure and from the first MQXFS1 test were reported earlier in [9].…”

Development of MQXF: The Nb₃Sn Low-<inline-formula> <tex-math notation="LaTeX">$\beta$</tex-math></inline-formula> Quadrupole for the HiLumi LHC

“…Excellent agreement was found between strain gauges mounted on dummy coils, shell and axial rods, and the prediction of the numerical model. A detailed analysis of the results is given in [24]. …”