Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature–Precision and Trueness Determination

Guinchard, Michael; Araújo, F. M.; Barbosa, C.; Bianchi, Laura; Cabon, Morgane; Ferreira, L. A.; Grosclaude, Philippe; Pereira, Alexandre Libório Dias

doi:10.1364/ofs.2018.wf85

Cited by 8 publications

(4 citation statements)

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“…In order to monitor the magnet mechanical behavior during the assembly and operation phases, MQXF model and prototype magnets at CERN have been equipped with mechanical instrumentation. Namely, electrical strain gauges and optic fibers (fiber bragg grating (FBG)) have been used to measure the structural deformation of the system at selected locations [69][70][71][72]. The magnet cross section is illustrated in figure 1; the position of the instrumentation is shown with round markers.…”

Section: Mqxf the Nb 3 Sn Low-β Quadrupole For Hl-lhcmentioning

confidence: 99%

Optimizing the use of pressurized bladders for the assembly of HL-LHC MQXFB magnets

Troitino

Ambrosio

Bourcey

et al. 2023

Supercond. Sci. Technol.

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The use of pressurized bladders for stress control of superconducting magnets was firstly proposed at Lawrence Berkeley National Laboratory (LBNL) in the early 2000s. Since then, the so-called “bladders and keys” procedure has become one of the reference techniques for the assembly of high-field accelerator magnets and demonstrators. Exploiting the advantages of this method is today of critical importance for Nb3Sn-based accelerator magnets, whose production requires the preservation of tight stress targets in the superconducting coils to limit the effects of the strain sensitivity and brittleness of the conductor. The present manuscript reports on the results of an experimental campaign focused on the optimization of the “bladders and keys” assembly process in the MQXFB quadrupoles. These 7.2 m. long magnets shall be among the first Nb3Sn cryomagnets to be installed in a particle accelerator as a part of the High Luminosity upgrade of the LHC. One of the main practical implications of the bladders technique, especially important when applied to long magnets like MQXFB, is that to insert the loading keys, the opening of a certain clearance in the support structure is required. The procedure used so far for MQXF magnets involved an overstress in the coils during bladder inflation. The work presented here shows that such an overshoot can be eliminated thanks to additional bladders properly positioned in the structure. This optimized method was validated in a short model magnet and in a full-length mechanical model, becoming the new baseline for the series production at CERN. Furthermore, the results are supported by numerical predictions using Finite Element models.

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Section: Mqxf the Nb 3 Sn Low-β Quadrupole For Hl-lhcmentioning

confidence: 99%

Optimizing the use of pressurized bladders for the assembly of HL-LHC MQXFB magnets

Troitino

Ambrosio

Bourcey

et al. 2023

Supercond. Sci. Technol.

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“…The sensors have demonstrated high dynamic range (45 dB) and megahertz measurement bandwidth-critically important for measuring the thermal shock strain response of a spallation target, as depicted in Figure 2. Fiber Bragg Grating (FBG) sensors have been used at accelerators [12,13], but there is no existing FBG processor that can achieve the high bandwidth needed for the strain signals. A higher bandwidth alternative is the laser doppler vibrometer (LDV) [13][14][15], however it only measures the normal/radial vibration at a single point (per LDV device).…”

Section: Figure 1 Conceptual Design Of Target Assembly Showing 21 Tar...mentioning

confidence: 99%

Second Target Station Project: LANSCE WNR Target 2 (Blue Room) Experiment 2022

Mach,

Tipton Jr.,

Blokland

et al. 2023

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“…The positions where the systems are installed correspond to the coil winding poles, the outer shell and the longitudinal tie rods (see figure 1). The measurements rely on active compensation schemes, which seek to remove from the strain readings the apparent effects derived from the magnet operation at cryogenic temperature, and from the presence of high magnetic fields (the last, just applicable for the electrical SGs) [90][91][92][93]. When compensated, the main objective of the mechanical instrumentation is to study the magnet response during the assembly and powering phases.…”

Section: Experimental Mechanical Readings During a Quenchmentioning

confidence: 99%

A methodology for the analysis of the three-dimensional mechanical behavior of a Nb₃Sn superconducting accelerator magnet during a quench

Troitino

Bajas

Bianchi

et al. 2021

Supercond. Sci. Technol.

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The fast thermal and electromagnetic transients that occur in a superconducting magnet in case of a quench have the potential of generating large mechanical stresses both in the superconducting coils and in the magnet structure. While the investigation of such quench loads should generally be conducted to ensure a safe operation of the system, its importance is greatly enlarged in the case of high-field magnets based on strain sensitive superconductors. For these, a rigorous analysis of the magnet mechanics during a quench becomes critical. The scope of this work is hence to bring, for the first time, a detailed understanding of the three-dimensional mechanical behavior of a Nb 3 Sn accelerator magnet during a quench discharge. The study relies on the use of finite element models, where various multi-domain simulations are employed together to solve the coupled physics of the problem. Our analysis elaborates on the case study of the new MQXF quadrupole magnet, currently being developed for the high-luminosity upgrade of the LHC. Notably, we could find a very good agreement between the results of the simulation and experimental data from full-scale magnet tests. The validated model confirms the appearance of new peak stresses in the superconducting coils. An increase in the most relevant transverse coil stresses of 20-40 MPa with respect to the values after magnet cool-down has been found for the examined case.

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Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature–Precision and Trueness Determination

Cited by 8 publications

References 0 publications

Optimizing the use of pressurized bladders for the assembly of HL-LHC MQXFB magnets

Optimizing the use of pressurized bladders for the assembly of HL-LHC MQXFB magnets

Second Target Station Project: LANSCE WNR Target 2 (Blue Room) Experiment 2022

A methodology for the analysis of the three-dimensional mechanical behavior of a Nb₃Sn superconducting accelerator magnet during a quench

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Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature–Precision and Trueness Determination

Cited by 8 publications

References 0 publications

Optimizing the use of pressurized bladders for the assembly of HL-LHC MQXFB magnets

Optimizing the use of pressurized bladders for the assembly of HL-LHC MQXFB magnets

Second Target Station Project: LANSCE WNR Target 2 (Blue Room) Experiment 2022

A methodology for the analysis of the three-dimensional mechanical behavior of a Nb3Sn superconducting accelerator magnet during a quench

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A methodology for the analysis of the three-dimensional mechanical behavior of a Nb₃Sn superconducting accelerator magnet during a quench