A First Baseline for the Magnets in the High Luminosity LHC Insertion Regions

Self Cite

Abstract-In preparation for the high luminosity upgrade of the Large Hadron Collider, the LHC Accelerator Research Program (LARP) in collaboration with CERN is pursuing the development of MQXF: a 150 mm aperture high-field Nb 3 Sn quadrupole magnet. The development phase starts with the fabrication and test of several short models (1.2 m magnetic length) and will continue with the development of several long prototypes. All of them are mechanically supported using a shell-based support structure, which has been extensively demonstrated on several R&D models within LARP. The first short model MQXFS-AT has been assembled at LBNL with coils fabricated by LARP and CERN. In this paper, we summarize the assembly process and show how it relies strongly on experience acquired during the LARP 120 mm aperture HQ magnet series. We present comparison between strain gauges data and finite element model analysis. Finally we present the implication of the MQXFS-AT experience on the design of the long prototype support structure.  Index Terms-High Luminosity LHC (HL-LHC), Interaction Regions, quadrupole, LARP, Nb 3 Sn magnet, shell-based support structure, short model.

Section: Introductionmentioning

confidence: 99%

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

Pan

Félice

Cheng

et al. 2016

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“…The US LHC Accelerator Research Program or LARP has developed Nb3Sn technology in quadrupole magnets starting from the 90 mm aperture Technology Quadrupole (TQ) and the 4.5 m magnetic length Long TQ [2], and moving toward the 120 mm aperture HQ and LHQ coils [3], [4]. LARP constructed a total of 26 HQ coils with multiple successful full magnet tests [5]- [8] and is the baseline design for the joint CERN/LARP development of the 150 mm MQXF IR quadrupoles [9], [10]. MQXF will operate at 16.5 kA with a peak field and gradient of 11.4 T and 132.6 T/m.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Analysis of 150 mm Aperture Nb<sub>3</sub>Sn LARP MQXF Coils

Holik

Ferracin

Krave

et al. 2016

Abstract-The US LHC Accelerator Research Program (LARP)and CERN are combining efforts for the HiLumi-LHC upgrade to design and fabricate 150 mm aperture, interaction region quadrupoles with a nominal gradient of 130 T/m using Nb3Sn. To successfully produce the necessary long MQXF triplets, the HiLumi-LHC collaboration is systematically reducing risk and design modification by heavily relying upon the experience gained from the successful 120 mm aperture LARP HQ program. First generation MQXF short (MQXFS) coils were predominately a scaling up of the HQ quadrupole design allowing comparable cable expansion during Nb3Sn formation heat treatment and increased insulation fraction for electrical robustness. A total of 13 first generation MQXFS coils were fabricated between LARP and CERN. Systematic differences in coil size, coil alignment symmetry, and coil length contraction during heat treatment are observed and likely due to slight variances in tooling and insulation/cable systems. Analysis of coil cross sections indicate that field-shaping wedges and adjacent coil turns are systematically displaced from the nominal location and the cable is expanding less than nominally designed. A second generation MQXF coil design seeks to correct the expansion and displacement discrepancies by increasing insulation and adding adjustable shims at the coil pole and midplanes to correct allowed magnetic field harmonics.

“…This 150 mm single aperture magnet called MQXF will provide a nominal field gradient of 132.6 T/m and will be installed in the LHC interaction regions during the High Luminosity LHC upgrade [2]. Its design is based on the 120 mm quadrupole magnet called HQ [3], which was developed by LARP, and utilizes the same bladder and key technology [4] for providing the coil preload.…”

Section: Introductionmentioning

confidence: 99%

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

Juchno

Ambrosio

Anerella

et al. 2016

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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.