Progress on HL-LHC Nb3Sn Magnets (original) (raw)
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IEEE Transactions on Applied Superconductivity, 2016
In the framework of the High-Luminosity upgrade of the Large Hadron Collider, the design and development of new magnets, relying on Nb 3 Sn superconducting cables, is progressing. In particular, a double-aperture dipole, with a bore diameter of 60 mm and a central field of 11 T, is required for the replacement of some Nb-Ti dipoles in the dispersion suppressor areas. The new magnets must comply with the specifications of the machine in terms of reliability and field quality. An intense short-model campaign was launched in order to validate the design choices. Various single-aperture models have been built and tested. Recently, the first 2-in-1 model has been produced by assembling the collared coils already tested in the single-aperture configuration. This paper presents the analysis of the magnetic measurements on the first 2-m-long, double-aperture demonstrator built and tested at CERN. The geometrical field multipoles, the iron saturation effects, the magnetic cross-talk as well as the effects of persistent currents are presented. The experimental data are compared with the magnetic calculations using the CERN field computation program ROXIE and are discussed in view of the construction of the full-length magnets.
R&D of Nb3Sn accelerator magnets at Fermilab
Applied …, 2005
Fermilab is developing and investigating different high-field magnet designs for present and future accelerators. The magnet R&D program was focused on the 10-12 T accelerator magnets based on Nb 3 Sn superconductor and explored both basic magnet technologies for brittle superconductors-wind-and-react and react-and-wind. Magnet design studies in support of LHC upgrades and VLHC are being performed. A series of 1-m long single-bore models of cos-theta Nb 3 Sn dipoles based on wind-andreact technique was fabricated and tested. Three 1-m long flat racetracks and the common coil dipole model, based on a singlelayer coil and wide reacted Nb 3 Sn cable, have also been fabricated and tested. Extensive theoretical studies of magnetic instabilities in Nb3Sn strands, cable and magnet were performed which led to successful 10 T dipole model. This paper presents the details of the Fermilab's high field accelerator magnet program, reports its status and major results, and formulates the program next steps.
Assembly and Test of SQ01b, a Nb3Sn Quadrupole Magnet for the LHC Accelerator Research Program
Lawrence Berkeley National Laboratory, 2009
The US LHC Accelerator Research Program (LARP) consists of four US laboratories (BNL, FNAL, LBNL, and SLAC) collaborating with CERN to achieve a successful commissioning of the LHC and to develop the next generation of Interaction Region magnets. In 2004, a large aperture Nb 3 Sn racetrack quadrupole magnet (SQ01) has been fabricated and tested at LBNL. The magnet utilized four subscale racetrack coils and was instrumented with strain gauges on the support structure and directly over the coil's turns. SQ01 exhibited training quenches in two of the four coils and reached a peak field in the conductor of 10.4 T at a current of 10.6 kA. After the test, the magnet was disassembled, inspected with pressure indicating films, and reassembled with minor modifications. A second test (SQ01b) was performed at FNAL and included training studies, strain gauge measurements and magnetic measurements. Magnet inspection, test results, and magnetic measurements are reported and discussed, and a comparison between strain gauge measurements and 3D finite element computations is presented.
Design of 11 T Twin-Aperture ${\rm Nb}_{3}{\rm Sn}$ Dipole Demonstrator Magnet for LHC Upgrades
IEEE Transactions on Applied Superconductivity, 2000
The LHC collimation upgrade foresees two additional collimators installed in the dispersion suppressor regions of points 2, 3 and 7. To obtain the necessary longitudinal space for the collimators, a solution based on an 11 T dipole as replacement of the 8.33 T LHC main dipoles is being considered. CERN and FNAL have started a joint development program to demonstrate the feasibility of Nb 3 Sn technology for this purpose. The program started with the development and test of a 2-m-long single-aperture demonstrator magnet. The goal of the second phase is the design and construction of a series of 2-m-long twin-aperture demonstrator magnets with a nominal field of 11 T at 11.85 kA current. This paper describes the electromagnetic design and gives a forecast of the field quality including saturation of the iron yoke and persistent-current effects in the Nb 3 Sn coils. The mechanical design concepts based on separate collared coils, assembled in a vertically split iron yoke are also discussed.
Power Test of the First Two HL-LHC Insertion Quadrupole Magnets Built at CERN
IEEE Transactions on Applied Superconductivity, 2022
The High-Luminosity project (HL-LHC) of the CERN Large Hadron Collider (LHC), requires low β* quadrupole magnets in Nb 3 Sn technology that will be installed on each side of the ATLAS and CMS experiments. After a successful shortmodel magnet manufacture and test campaign, the project has advanced with the production, assembly, and test of full-size 7.15m-long magnets. In the last two years, two CERN-built prototypes (MQXFBP1 and MQXFBP2) have been tested and magnetically measured at the CERN SM18 test facility. These are the longest accelerator magnets based on Nb 3 Sn technology built and tested to date. In this paper, we present the test and analysis results of these two magnets, with emphasis on quenches and training, voltage-current measurements and the quench localization with voltage taps and a new quench antenna. Index Terms-Low beta quadrupole, Nb 3 Sn, quench, superconducting magnets. I. INTRODUCTION A S PART of the HL-LHC project at CERN, the Nb-Ti inner triplet quadrupole magnets near the ATLAS and CMS interaction points will be replaced with large aperture Nb 3 Sn quadrupole magnets, named MQXF [1], [2]. These magnets are developed, manufactured, and tested in a collaboration between CERN and the US HL-LHC Accelerator Upgrade Project (AUP). The MQXF program includes the construction and test of several short-length model magnets, the 4.2-m-long magnets for Q1 and Q3 (constructed by AUP [3]), and the 7.15-m-long magnets for Q2a and Q2b (MQXFB, constructed by CERN). The first two MQXFB full-length prototype magnets (MQXFBP1 and MQXFBP2) were manufactured, assembled and cryostated at CERN [4]. MQXFBP1 was tested in summer-fall 2020, and MQXFBP2 was tested in winter-spring and fall 2021.
Progress on the Development of the Nb3Sn 11T Dipole for the High Luminosity Upgrade of LHC
IEEE Transactions on Applied Superconductivity, 2017
The High Luminosity LHC Project at CERN entered into the production phase in October 2015 after the completion of the design study phase. In the meantime, the development of the 11 T dipole needed for the upgrade of the collimation system of the machine made significant progress with very good performance of the first two-in-one magnet model of 2-m length made at CERN. The 11 T dipole, which is more powerful than the current main dipoles of LHC, can be made shorter with an equivalent integrated field. This will allow creating space for the installation of additional collimators in specific locations of the dispersion suppressor regions. Following tests carried out during heavy ions runs of LHC in the end of 2015, and a more recent review of the project budget, the installation plan for the 11 T dipole was revised. Consequently, one 11 T dipole full assembly containing two 11 T dipoles of 5.5-m length will be installed on either side of interaction point 7. These two units shall be installed during the long shutdown 2 in years 2019-2020. After a brief reminder on the design features of the magnet, this paper describes the current status of the development activities, in particular the short model programme and the construction of the first full scale prototype at CERN. Critical operations like the reaction treatment and the coil impregnation are discussed, the quench performance tests results of the two-in-one model are reviewed and finally, the plan towards the production for the long shut downs 2 is described. Index Terms-Accelerator magnets, high-luminosity large hadron collider (LHC) project, Nb3Sn 11 T dipole, superconducting magnets.
Status of the MQXFB Nb3Sn Quadrupoles for the HL-LHC
IEEE Transactions on Applied Superconductivity
The cold powering test of the first two prototypes of the MQXFB quadrupoles (MQXFBP1, now disassembled, and MQXFBP2), the Nb3Sn 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 Nb3Sn 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. Index Terms-Nb3Sn, Accelerator Magnets, HL-LHC I. INTRODUCTION HE High Luminosity Upgrade of the Large Hadron Collider aims at increasing the integrated luminosity by a factor 10 [1]. One of the main components of the upgrade are the triplet quadrupoles (Q1, Q2a, Q2b, Q3) [2]. With respect to the current triplet quadrupoles, the new magnets called MQXF, will feature a larger aperture, from 70 mm to 150 mm, a higher peak field, from 8.6 T to 11.3 T, and a different superconducting material, Nb3Sn instead of Nb-Ti [3]. The magnetic length of Q1/Q3 is 8.4 m, split in two magnets of 4.2 m (MQXFA) which are being fabricated by the US Accelerator Research Program (AUP) [4], a continuation of LARP (LHC Manuscript receipt and acceptance dates will be inserted here.
Models and experimental results from the wide aperture Nb-Ti magnets for the LHC upgrade
MQXC is a Nb-Ti quadrupole designed to meet the accelerator quality requirements needed for the phase-1 LHC upgrade, now superseded by the high luminosity upgrade foreseen in 2021. The 2-m-long model magnet was tested at room temperature and 1.9 K. The technology developed for this magnet is relevant for other magnets currently under development for the highluminosity upgrade, namely D1 (at KEK) and the large aperture twin quadrupole Q4 (at CEA). In this paper we present MQXC test results, some of the specialized heat extraction features, spot heaters, temperature sensor mounting and voltage tap development for the special open cable insulation. We look at some problem solving with noisy signals, give an overview of electrical testing, look at how we calculate the coil resistance during at quench and show that the heaters are not working We describe the quench signals and its timing, the development of the quench heaters and give an explanation of an Excel quench calculation and its comparison including the good agreement with the MQXC test results. We propose an improvement to the magnet circuit design to reduce voltage to ground values by factor 2. The program is then used to predict quench Hot-Spot and Voltages values for the D1 dipole and the Q4 quadrupole.
Status of the 11 T Nb3Sn Dipole Project for the LHC
IEEE Transactions on Applied Superconductivity, 2014
The planned upgrade of the LHC collimation system includes additional collimators in the LHC lattice. The longitudinal space for the collimators could be obtained by replacing some LHC main dipoles with shorter but stronger dipoles compatible with the LHC lattice and main systems. A joint development program with the goal of building a 5.5 m long two-in-one aperture Nb 3 Sn dipole prototype suitable for installation in the LHC is being conducted by FNAL and CERN magnet groups. As part of the first phase of the program, 1 m long and 2 m long single aperture models are being built and tested, and the collared coils from these magnets will be assembled and tested in two-in-one configuration in both laboratories. In parallel with the short model magnet activities, the work has started on the production line in view of the scaleup to 5.5 m long prototype magnet. The development of the final cryo-assembly comprising two 5.5 m long 11T dipole cold masses and the warm collimator in the middle, fully compatible with the LHC main systems and the existing machine interfaces, has also started at CERN. This paper summarizes the progress made at CERN and FNAL towards the construction of 5.5 m long 11 T Nb 3 Sn dipole prototype and the present status of the activities related to the integration of the 11 T dipole and collimator in the LHC.
IEEE Transactions on Applied Superconductivity, 2000
In support of the luminosity upgrade of the Large Hadron Collider (LHC), the US LHC Accelerator Research Program (LARP) has been developing a 1-meter long, 120 mm bore Nb 3 Sn IR quadrupole magnet (HQ). With a short sample gradient of 219 T/m at 1.9 K and a conductor peak field of 15 T, the magnet will operate under higher forces and stored-energy levels than that of any previous LARP magnet models. In addition, HQ has been designed to incorporate accelerator quality features such as precise coil alignment and adequate cooling. The first 6 coils (out of the 8 fabricated so far) have been assembled and used in two separate tests-HQ01a and HQ01b. This paper presents design parameters, summary of the assemblies, the mechanical behavior as well as the performance of HQ01a and HQ01b.