The HL-LHC Low-β Quadrupole Magnet MQXF: From Short Models to Long Prototypes

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The Nb 3 Sn quadrupole MQXF is being developed as a part of the LHC High Luminosity upgrade. The magnet design was tested on 1.5 m long short models, sharing the same cross-section with the full-length magnets. Various azimuthal and longitudinal preloads were applied, studying the impact on the magnet training and on its mechanical performances. The experiments demonstrated the possibility to control the magnet prestress. However, various factors, coil size among the others, may affect the stress variation between and within each winding. This variation could prevent the magnet to reach the desired performances, for example as result of critical current degradation of the Nb 3 Sn strands. This paper analyzes the mechanical performances of the short models, studying in particular the stress variation on different coils. The measured coil size was used as input in the numerical simulations, and results were then compared with the strain gauge measurements. Finally, the short models experience was used to evaluate the feasibility of a loading operation that does not rely on the strain measurements.

Section: Mqxf Short Model Magnetsmentioning

confidence: 93%

Summary of the Mechanical Performances of the 1.5 m Long Models of the Nb<inline-formula> <tex-math notation="LaTeX">$_{3}$</tex-math> </inline-formula>Sn Low-<inline-formula> <tex-math notation="LaTeX">$\beta$</tex-math> </inline-formula> Quadrupole MQXF

Vallone

Ambrosio

Anderssen

et al. 2019

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“…As same as the previous LARP HQ and MQXFS magnets [2], MQXFA magnet has the same cross section (Fig. 1), and relies on the pre-tension of the aluminum 7075-T6 shell, which is pre-loaded at room temperature [3,4] with the bladder-and-key technology.…”

Section: Introductionmentioning

confidence: 93%

Fracture Failure Analysis for MQXFA Magnet Aluminum Shells

Pan

Anderssen

Ambrosio

et al. 2020

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The High-Luminosity LHC Accelerator Upgrade Project (HL-LHC AUP) is approaching the production phase of the US-contributed Q1 and Q3 Interaction Region Quadrupoles (MQXFA). The structures for the MQXFA prototypes were design and inspected by the US-LARP (LHC Accelerator Research Program), AUP developed criteria, which will be used for the pre-series structures. As the first two full-length prototypes with 4.2 m magnetic length, MQXFAP1 and MQXFAP2, were designed and assembled at Lawrence Berkeley National Laboratory (LBNL), and tested at Brookhaven National Laboratory (BNL). The end aluminum short shell of MQXFAP2 was fractured along the shell length during the test, and tests were stopped. Analytical and Finite Element analysis were performed in light of the graded procedure defined in the Structure Design Criteria to investigate the fracture failure for MQXFAP2. In this paper, we report the fracture analysis of the current shell design, including the elasto-plastic simulations with submodel technique, and calculations with Linear Elastic Fracture Mechanics (LEFM). Test material properties are also presented. The results of this analysis explain why the end shell of MQXFAP2 failed, and suggest fillets on the end shell notches to meet the margin specified in the Structural Design Criteria.

“…It should also be noted that the maximum allowed hot spot temperature for training quenches is 250 K. The corresponding quench integral (∫I 2 dt) value depends on the conductor used in each magnet. The MIIts value for MQXFAP1/P1b is shown in parentheses and is different because the conductor is different from the other magnets [1]. A higher temperature of 350 K was allowed only for the prototypes, after training was completed, and only during quench protection studies.…”

Section: Magnet Descriptionmentioning

confidence: 99%

Test Results of the First Two Full-Length Prototype Quadrupole Magnets for the LHC Hi-Lumi Upgrade

Muratore

Amm

Anerella

et al. 2020

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The future high luminosity (Hi-Lumi) upgrade of the Large Hadron Collider (LHC) at CERN will include eight (plus two spares) 8.4 m-long cryostatted cold masses which will be components of the triplets for two LHC insertion regions. Each cold mass will consist of two 4.2 m long Nb3Sn high gradient quadrupole magnets, designated MQXFA, with aperture 150 mm and operating gradient 132.6 T/m, for a total of twenty magnets. Before assembling and testing the final cold masses at Fermilab, the twenty component quadrupoles will be tested first at the vertical superconducting magnet test facility of the Superconducting Magnet Division at Brookhaven National Laboratory (BNL), in superfluid He at 1.9 K and to 18.0 kA, to meet LHC operational requirements. The first two full-length prototype quadrupole magnets, MQXFAP1 and MQXFAP2, have been tested at BNL. This paper reports on the quench test and training results of these magnets, and also the retest of the first prototype, rebuilt and designated as MQXFAP1b. The test results of these magnets will be important for validating the MQXFA design.