The high-luminosity upgrade of the Large Hadron Collider (HL-LHC) requires new high field and large-aperture quadrupole magnets for the low-beta inner triplets (MQXF). With a nominal operating ...gradient of 132.2 T/m in a 150 mm aperture and a conductor peak field of 11.3 T, the new quadrupole magnets are based on Nb 3 Sn superconducting technology. After a series of short models constructed in close collaboration by LARP (LHC Accelerator Research Program) and CERN, the development program is entering in the series production phase with CERN on one side and the US Accelerator Upgrade Project (US-AUP) on the other side assembling and testing full-length magnets. This paper describes the status of the development activities at CERN, in particular on the cold powering test of the first MQFXB prototype and on the construction of the second full scale prototype. Critical operations such as reaction heat treatment, coil impregnation and magnet assembly are discussed. Finally, the plan towards the series production is described.
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In the early 2000's, the US High Energy Physics community contributing to the Large Hadron Collider (LHC) launched the LHC Accelerator R&D Program (LARP), a long-vision focused R&D program, intended ...to contribute to a quick LHC commissioning and to bring the Nb3Sn and other technologies to a maturity level that would allow applications in HEP machines. Around 2015, the technologies developed by LARP, CERN and other institutions were mature enough to allow the spin-off of a major upgrade project to the LHC complex, the High Luminosity LHC (HL-LHC) 3. This paper will focus on the US contribution to HL-LHC, namely the large-aperture low-β focusing Nb3Sn quadrupoles and the Radio Frequency Dipole (RFD) Crab Cavities, located in close proximity to the ATLAS and CMS experiments. This contribution, called the HL-LHC Accelerator Upgrade Project (HL-LHC AUP), focuses on production of these quadrupoles and cavities by sharing the work among a consortium of US Laboratories (FNAL, LBNL, BNL and SLAC) and Universities and in close connection with the CERN-led HL-LHC Collaboration. The collaboration achieved commonality of specifications and uniformity of performance. Final development of design, construction and first results from the prototypes are described to indicate the status of these critical components for HL-LHC.
Superconducting magnet training is one of the accelerator related issues attracting attention due to significant operational costs and time budget associated to it. It is especially worrisome that ...magnets based on the "next-generation" Nb 3 Sn technology are affected by long training. While various efforts are underway to better understand and resolve the problem a parallel path could also be investigated, a path bypassing the issue. Following the concept of fast induced over-current during magnet powering, FNAL has developed an upgradable capacitor-based device to discharge through a superconducting magnet at quench detection or operator chosen time. The 0.4 F/1 kV device has been tested on a 1-m-long dipole-coil in a "mirror" magnet configuration and conclusive results on magnet training elimination have been observed. In this paper we discuss the main characteristics of the device, compare simulated response and actual performance, elaborate on test drivers and outcomes. Next steps and perspectives for future use are debated.
The Muon Ionization Cooling Experiment located at Rutherford Appleton Laboratory in England utilizes a superconducting solenoid system for the muon cooling channel that also holds particle-tracking ...detectors and muon absorbers inside their bores. The solenoid system installation was completed in summer of 2015 and after commissioning the system it has been running successfully. This paper summarizes the commissioning results and operational experience with the magnets focusing on the performance of the two spectrometer solenoids built by the U.S.
The future High Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN will include the low-beta inner triplets (Q1, Q2a/b, Q3) for two LHC insertion regions. The Q1, Q3 components consist ...of eight 10 m-long LMQXFA cryo-assemblies fabricated by the HL-LHC Accelerator Upgrade Project. Each LMQXFA Cold mass contains two Nb3Sn magnets connected in series. A stainless-steel shell is welded around the two magnets before the insertion into the cryostat. There is a limit on how much coil preload increase induced by the shell welding is allowed. Distributed Rayleigh backscattering fiber optics sensors were used for the first time to obtain a strain map over a wide area of a Nb3Sn magnet cold mass shell. Data were collected during welding of the first LMQXFA cold mass and the results confirm that the increase of the coil pole azimuthal pre-stress after welding do not exceed requirements.
Fermilab is fabricating ten full length cold masses for the high-luminosity Large Hadron Collider Accelerator Upgrade Project (HL-LHC AUP). One practice assembly and one pre-series assembly have been ...completed. This paper summarizes the con-struction details. Topics include incoming inspection, bus assembly, component machining, shell forming, beam tube insertion, bus expansion loop installation, instrumentation installation, electrical testing, heat exchanger installation and final assembly welding. In-process surveys, alignment measurements and testing are presented and explained. Problems encountered during construction and their solutions are discussed.
The MQXFA production series quadrupoles being built for the Hi-Lumi (HL) LHC upgrade by the US Accelerator Upgrade Project (US-HL-LHC AUP) will have very limited voltage instrumentation for ...characterizing quench events that occur during magnet training and performance validation testing. In order to understand the origin of the quenches, and whether they have some implication for ongoing magnet fabrication, a full-length Quench Antenna Array (QAA) was built with axial resolution of 50 mm to be employed during cold testing in the anti-cryostat. The goal is to have fine-resolution, full-length coverage detection of quench events axially, as well as to have azimuthal resolution on the order of the cable width (about 1 degree for the cross-section), in a device that can be used both for vertical and horizontal testing. To achieve this, a 5 m long QAA with 128 channels of high-speed data acquisition has been designed and fabricated. The array features full-length radially positioned antennas for azimuthal localization, and short, high-sensitivity, antennas for axial detection. This paper discusses the design, construction and analysis of the MQXFA QAA, and first results from its use during quench testing in the production magnets.
Status of the MQXFB Nb3Sn quadrupoles for the HL-LHC Bermudez, Susana Izquierdo; Ambrosio, Giorgio; Apollinari, Giorgio ...
IEEE transactions on applied superconductivity,
08/2023, Letnik:
33, Številka:
5
Journal Article
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The cold powering test of the first two prototypes of the MQXFB quadrupoles (MQXFBP1, now disassembled, and MQXFBP2), the Nb 3 Sn inner triplet magnets to be installed in the HL-LHC, has validated ...many features of the design, such as field quality and quench protection, but has found performance limitations. In fact, both magnets showed a similar phenomenology, characterized by reproducible quenches in the straight part inner layer pole turn, with absence of training and limiting the performance at 93% (MQXFBP1) and 98% (MQXFBP2) of the nominal current at 1.9 K, required for HL-LHC operation at 7 TeV. Microstructural inspections of the quenching section of the limiting coil in MQXFBP1 have identified fractured Nb 3 Sn sub-elements in strands located at one specific position of the inner layer pole turn, allowing to determine the precise origin of the performance limitation. In this paper we outline the strategy that has been defined to address the possible sources of performance limitation, namely coil manufacturing, magnet assembly and integration in the cold mass.
Status of the MQXFB Nb 3 Sn Quadrupoles for the HL-LHC Bermudez, Susana Izquierdo; Ambrosio, Giorgio; Apollinari, Giorgio ...
IEEE transactions on applied superconductivity,
8/2023, Letnik:
33, Številka:
5
Journal Article
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