The cold powering test of the first two prototypes of the MQXFB quadrupoles (MQXFBP1, now disasse... more 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.
IEEE Transactions on Applied Superconductivity, 2022
The High-Luminosity project (HL-LHC) of the CERN Large Hadron Collider (LHC), requires low β* qua... more 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.
IEEE Transactions on Applied Superconductivity, 2017
The High Luminosity LHC Project at CERN entered into the production phase in October 2015 after t... more 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.
IEEE Transactions on Applied Superconductivity, 2018
The luminosity upgrade of the Large Hadron Collider (LHC) at CERN requires the installation of ad... more The luminosity upgrade of the Large Hadron Collider (LHC) at CERN requires the installation of additional collimators in the dispersion suppressor regions of the accelerator. The upgrade foresees the installation of one additional collimator on either side of interaction point 7 (IP7) at the location of the existing main dipoles (MBs) that will be replaced by shorter and more powerful dipoles, and of one additional collimator on either side of IP2 at the location of existing empty cryostats. This paper describes the design and the construction status of the full-length prototype of the 11-T dipole magnet, which is needed for IP7. This magnet features a two-in-one structure, like the LHC MB, impregnated coils made of Nb 3 Sn conductor, an inner bore of 60 mm, and a magnetic length of about 5.3 m. Two 11-T magnets are needed to replace a 15-m long MB. A bypass cryostat placed in between the two magnets allows creating a room temperature space for the additional collimators. The magnet is designed to provide the same integrated field as the MB at nominal field. However, due to the difference in transfer function at lower field, a correction by means of a trim current has been considered. A full-length prototype is currently under construction at CERN with the goal of developing the manufacturing and inspection procedures prior to launch the series production. For this, new tooling has been developed and optimized during the fabrication of fully representative practice coils. This paper describes the design of the magnet, the main manufacturing steps, and corresponding quality indicators, which will be used to monitor the series production. Finally, the production and installation schedule will be presented.
IEEE Transactions on Applied Superconductivity, 2019
Among the components to be upgraded in LHC interaction regions for the HiLumi-LHC projects are th... more Among the components to be upgraded in LHC interaction regions for the HiLumi-LHC projects are the inner triplet (or low-β) quadrupole magnets, denoted as Q1, Q2a, Q2b, and Q3. The new quadrupole magnets, called MQXF, are based on Nb3Sn superconducting magnet technology and operate at a gradient of 132.6 T/m with a conductor peak field of 11.4 T. The Q1 and Q3 are composed by magnets (called MQXFA) fabricated by the US Accelerator Upgrade Project (AUP) with a magnetic length of 4.2 m. The Q2a and Q2b consists of magnets (called MQXFB) fabricated by CERN with a magnetic length of 7.15 m. After a series of short models, constructed in close collaboration by the US and CERN, the development program is now entering in the prototyping phase, with CERN on one side and BNL, FNAL, and LBNL on the other side assembling and testing their first long magnets. We provide in this paper a description of the status of the MQXF program, with a summary of the short model test results, including quench performance, and mechanics, and an update on the fabrication, assembly and test of the long prototypes.
The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting mag... more The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting magnets include thermal shielding at 50-75 K, providing continuity to the thermal shielding of the magnet cryostats to reduce the overall radiation heat loads to the 1.9 K helium bath of the magnets. The IC shield, made of aluminum, is conduction-cooled via a welded bridge to the thermal shield of the adjacent magnets which is actively cooled. TIG welding of these bridges made in the LHC tunnel at installation of the magnets induced a considerable risk of fire hazard due to the proximity of the multi-layer insulation of the magnet shields. A fire incident occurred in one of the machine sectors during machine installation, but fortunately with limited consequences thanks to prompt intervention of the operators. LHC is now undergoing a 2 years technical stop during which all magnet's ICs will have to be opened to consolidate the magnet electrical connections. The IC thermal shields will therefore have to be removed and re-installed after the work is completed. In order to eliminate the risk of fire hazard when re-welding, it has been decided to review the design of the IC shields, by replacing the welded bridges with a mechanical clamping which also preserves its thermal function. An additional advantage of this new solution is the ease in dismantling for maintenance, and eliminating weld-grinding operations at removal needing radioprotection measures because of material activation after long-term operation of the LHC. This paper describes the new design of the IC shields and in particular the theoretical and experimental validation of its thermal performance. Furthermore a status report of the ongoing upgrade work in the LHC is given.
IOP Conference Series: Materials Science and Engineering
The high luminosity LHC project (HL-LHC) aims at increasing proton collisions by a factor of ten ... more The high luminosity LHC project (HL-LHC) aims at increasing proton collisions by a factor of ten whilst extending physics exploitation until 2035. Its performance will rely on new focusing quadrupoles, beam separation dipoles and corrector magnets with large apertures to be installed on both sides of the ATLAS and CMS experiments. A dedicated cryostat design of about 1 m in diameter was developed for operation of these magnets at 1.9 K, comprising the required cryogenic circuits, interconnects, supports, insulation, and instrumentation systems. Six cryostats with various lengths in the range of 8 to 11 m are required on each side of the interaction points to house the triplet magnets, correctors and the first separation dipole. These cryostats will be linked through flexible interconnects to form a continuous vacuum insulation and cryogenic system of about 60 m in length. The second rearmost separation dipole requires a stand-alone cryostat of 15 m in length but nevertheless feature...
IEEE Transactions on Applied Superconductivity, 2022
As part of the U.S. contribution to the HL-LHC Accelerator Upgrade Project (AUP), Fermilab is des... more As part of the U.S. contribution to the HL-LHC Accelerator Upgrade Project (AUP), Fermilab is designing and building cold masses suitable for use in the LHC interaction regions. The cold mass provides a vacuum-tight helium enclosure for the magnets. Two magnets are aligned both axially and in cross section at Fermilab based on survey and warm magnetic measurements. Bus work and instrumentation is added. A welded stainless steel vacuum-tight shell surrounds the two magnets, and the structure is prepared for insertion into the cryostat. This paper summarizes the design of the cold mass including alignment, bus work, weld details, and instrumentation.
Chapter 11 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Lar... more Chapter 11 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity (rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology bey...
IEEE Transactions on Applied Superconductivity, 2016
The Large Hadron Collider (LHC) collimation system upgrade plan comprises new collimators in the ... more The Large Hadron Collider (LHC) collimation system upgrade plan comprises new collimators in the dispersion suppressors. The length required for each collimator along the LHC lattice is obtained by replacing an LHC main dipole and its cryostat with two shorter but stronger 11-T Nb3Sn magnets keeping the equivalent integrated field of the dipole removed. This requires a modification of the continuous cryostat, in order to create room-temperature beam vacuum sectors for the integration of the new collimators. In this paper, we present a new cryostat designed to allow the installation of a collimator between the 11-T magnets, while ensuring the continuity of the cryogenics, vacuum, and magnet powering systems of the LHC continuous cryostat. Challenging constraints, in terms of fabrication, alignment, and space, led to the development of a cryostat composed of three independent modules. Two of the modules house the 11-T dipole cold masses, which are cooled in the same 1.9-K pressurized superfluid helium bath of the main dipoles. These make use of the same design features of the LHC magnet cryostats, in order to contain construction and assembly costs and benefit from well-established procedures. A third module, which is placed between the two magnets, is equipped with cold to warm transitions on the beam lines and creates the space for the collimator between the vacuum vessel of the two 11-T magnet cryostats. The main functionalities, requirements, and implemented design solutions for this new cryostat are presented and discussed, in the context of the challenging integration in the LHC continuous cryostat and its tunnel.
IEEE Transactions on Applied Superconductivity, 2009
AbstractThe low-triplets of the Large Hadron Collider were designed and constructed by a world-w... more AbstractThe low-triplets of the Large Hadron Collider were designed and constructed by a world-wide collaboration officially formed in 1998. Over the course of the following years the col-laboration worked to produce the triplet components, including four 215 T/m, 70 mm ...
The insertion regions located around the four interaction points of the Large Hadron Collider (LH... more The insertion regions located around the four interaction points of the Large Hadron Collider (LHC) are mainly composed of the low-β triplets, the separation dipoles and their respective electrical feed-boxes (DFBX). The low-β triplets are Nb-Ti superconductor quadrupole magnets, which operate at 215 T/m in superfluid helium at a temperature of 1.9 K. The commissioning and the first operation of these components have been performed. The thermo-mechanical behavior of the low-β triplets and DFBX were studied. Cooling and control systems were tuned to optimize the cryogenic operation of the insertion regions. Hardware commissioning also permitted to test the system response. This paper summarizes the performance results and the lessons learned.
Integrating the large and complex LHC machine into the existing LEP tunnel is a major challenge. ... more Integrating the large and complex LHC machine into the existing LEP tunnel is a major challenge. Space was not really a problem to fit the LEP machine into its tunnel, but LHC cryostats are much larger than the LEP quadrupoles and the external cryogenic line fills even more the tunnel. Space problems lead to small clearances. Possible conflicts, or at least the most penalising ones, between installed equipment or with transport, must be solved beforehand in order to avoid unacceptable delays and extra costs during the installation. Experience gained with LEP has already shown the help that Computer-Aided Engineering tools could provide for the integration. A virtual model of the LHC is presently prepared. The actual LEP tunnel, known with a quite good accuracy (centimetre level), has been modelled and all the elements of the machine constructed as 3D objects with the CAD system are positioned accurately on the basis of data generated from the theoretical definition. These layouts ar...
INDIVIDUAL MAGNETS The optics flexibility of the LHC insertions is provided by the individually p... more INDIVIDUAL MAGNETS The optics flexibility of the LHC insertions is provided by the individually powered superconducting quadrupoles in the dispersion suppressors and matching sections. These cryo-magnets comprise special quadrupoles of the MQM and MQY type, and range in length from 5.4 m to 11.4 m. In total, 82 insertion quadrupoles will be assembled at CERN. In this paper we present the progress in fabrication and report on the performance of the first series quadrupoles. In particular, we present the quench performance of individual magnets and discuss the field quality trends and improvements based on magnet sorting. Quench training The quench history of the eight tested MQM magnets is
Following the incident in one of the main dipole circuits of the Large Hadron Collider (LHC) in S... more Following the incident in one of the main dipole circuits of the Large Hadron Collider (LHC) in September 2008, a detailed analysis of all magnet circuits has been performed by a dedicated task force. This analysis has revealed critical issues in the design of the 13 kA splices between the superconducting dipole and quadrupole magnets. These splices have to be consolidated before increasing the beam energy above 4 TeV and operating the LHC at 6.5-7 TeV per beam. The design of the consolidated 13 kA splices is complete and has been reviewed by an international committee of experts. Also, all other types of superconducting circuits have been thoroughly screened for potential safety issues and several important recommendations were established. They were critically assessed and the resulting actions are presented. In addition to the work on the 13 kA splices, other interventions will be performed during the first long shut-down of the LHC to consolidate globally all superconducting cir...
New low-β quadrupole magnets are being developed within the scope of the High Luminosity LHC (HL-... more New low-β quadrupole magnets are being developed within the scope of the High Luminosity LHC (HL-LHC) project in collaboration with the US LARP program. The aim of the HLLHC project is to study and implement machine upgrades necessary for increasing the luminosity of the LHC. The new quadrupoles, which are based on the Nb3Sn superconducting technology, will be installed in the LHC Interaction Regions and will have to generate a gradient of 140 T/m in a coil aperture of 150 mm. In this paper, we describe the design of the short model magnet support structure and discuss results of the detailed 3D numerical analysis performed in preparation for the first short model test.
To eliminate the risk of thermal runaways in LHC interconnections a consolidation by placing shun... more To eliminate the risk of thermal runaways in LHC interconnections a consolidation by placing shunts on the main bus bar interconnections is proposed by the Task Force Splices Consolidation. To validate the design two special SSS magnet spares are placed on a test bench in SM-18 to measure the interconnection in between with conditions as close as possible to the LHC conditions. Two dipole interconnections are instrumented and prepared with worst-case-conditions to study the thermo-electric stability limits. Two quadrupole interconnections are instrumented and prepared for studying the effect of current cycling on the mechanical stability of the consolidation design. All 4 shunted interconnections showed very stable behaviour, well beyond the LHC design current cycle.
IEEE Transactions on Applied Superconductivity, 2017
The high luminosity Large Hadron Collider (LHC) upgrade target is to increase the integrated lumi... more The high luminosity Large Hadron Collider (LHC) upgrade target is to increase the integrated luminosity by a factor 10, resulting in an integrated luminosity of 3000 fb -1 . One major improvement foreseen is the reduction of the beam size at the collision points. This requires the development of 150-mm single-aperture quadrupoles for the interaction regions. These quadrupoles are under development in a joint collaboration between CERN and the US-LHC Accelerator Research Program. The chosen approach for achieving a nominal quadrupole field gradient of 132.6 T/m is based on the Nb 3 Sn technology. The coils with a length of 7281 mm will be the longest Nb 3 Sn coils fabricated so far for accelerator magnets. The production of the long coils was launched in 2016 based on practise coils made from copper. This paper provides a status of the tooling development and production of the first copper coil, from winding, curing, and reaction heat treatment. In addition, an overview of the upcoming coil vacuum impregnation and the development of the magnet assembly including a prototype production schedule are provided.
The cold powering test of the first two prototypes of the MQXFB quadrupoles (MQXFBP1, now disasse... more 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.
IEEE Transactions on Applied Superconductivity, 2022
The High-Luminosity project (HL-LHC) of the CERN Large Hadron Collider (LHC), requires low β* qua... more 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.
IEEE Transactions on Applied Superconductivity, 2017
The High Luminosity LHC Project at CERN entered into the production phase in October 2015 after t... more 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.
IEEE Transactions on Applied Superconductivity, 2018
The luminosity upgrade of the Large Hadron Collider (LHC) at CERN requires the installation of ad... more The luminosity upgrade of the Large Hadron Collider (LHC) at CERN requires the installation of additional collimators in the dispersion suppressor regions of the accelerator. The upgrade foresees the installation of one additional collimator on either side of interaction point 7 (IP7) at the location of the existing main dipoles (MBs) that will be replaced by shorter and more powerful dipoles, and of one additional collimator on either side of IP2 at the location of existing empty cryostats. This paper describes the design and the construction status of the full-length prototype of the 11-T dipole magnet, which is needed for IP7. This magnet features a two-in-one structure, like the LHC MB, impregnated coils made of Nb 3 Sn conductor, an inner bore of 60 mm, and a magnetic length of about 5.3 m. Two 11-T magnets are needed to replace a 15-m long MB. A bypass cryostat placed in between the two magnets allows creating a room temperature space for the additional collimators. The magnet is designed to provide the same integrated field as the MB at nominal field. However, due to the difference in transfer function at lower field, a correction by means of a trim current has been considered. A full-length prototype is currently under construction at CERN with the goal of developing the manufacturing and inspection procedures prior to launch the series production. For this, new tooling has been developed and optimized during the fabrication of fully representative practice coils. This paper describes the design of the magnet, the main manufacturing steps, and corresponding quality indicators, which will be used to monitor the series production. Finally, the production and installation schedule will be presented.
IEEE Transactions on Applied Superconductivity, 2019
Among the components to be upgraded in LHC interaction regions for the HiLumi-LHC projects are th... more Among the components to be upgraded in LHC interaction regions for the HiLumi-LHC projects are the inner triplet (or low-β) quadrupole magnets, denoted as Q1, Q2a, Q2b, and Q3. The new quadrupole magnets, called MQXF, are based on Nb3Sn superconducting magnet technology and operate at a gradient of 132.6 T/m with a conductor peak field of 11.4 T. The Q1 and Q3 are composed by magnets (called MQXFA) fabricated by the US Accelerator Upgrade Project (AUP) with a magnetic length of 4.2 m. The Q2a and Q2b consists of magnets (called MQXFB) fabricated by CERN with a magnetic length of 7.15 m. After a series of short models, constructed in close collaboration by the US and CERN, the development program is now entering in the prototyping phase, with CERN on one side and BNL, FNAL, and LBNL on the other side assembling and testing their first long magnets. We provide in this paper a description of the status of the MQXF program, with a summary of the short model test results, including quench performance, and mechanics, and an update on the fabrication, assembly and test of the long prototypes.
The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting mag... more The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting magnets include thermal shielding at 50-75 K, providing continuity to the thermal shielding of the magnet cryostats to reduce the overall radiation heat loads to the 1.9 K helium bath of the magnets. The IC shield, made of aluminum, is conduction-cooled via a welded bridge to the thermal shield of the adjacent magnets which is actively cooled. TIG welding of these bridges made in the LHC tunnel at installation of the magnets induced a considerable risk of fire hazard due to the proximity of the multi-layer insulation of the magnet shields. A fire incident occurred in one of the machine sectors during machine installation, but fortunately with limited consequences thanks to prompt intervention of the operators. LHC is now undergoing a 2 years technical stop during which all magnet's ICs will have to be opened to consolidate the magnet electrical connections. The IC thermal shields will therefore have to be removed and re-installed after the work is completed. In order to eliminate the risk of fire hazard when re-welding, it has been decided to review the design of the IC shields, by replacing the welded bridges with a mechanical clamping which also preserves its thermal function. An additional advantage of this new solution is the ease in dismantling for maintenance, and eliminating weld-grinding operations at removal needing radioprotection measures because of material activation after long-term operation of the LHC. This paper describes the new design of the IC shields and in particular the theoretical and experimental validation of its thermal performance. Furthermore a status report of the ongoing upgrade work in the LHC is given.
IOP Conference Series: Materials Science and Engineering
The high luminosity LHC project (HL-LHC) aims at increasing proton collisions by a factor of ten ... more The high luminosity LHC project (HL-LHC) aims at increasing proton collisions by a factor of ten whilst extending physics exploitation until 2035. Its performance will rely on new focusing quadrupoles, beam separation dipoles and corrector magnets with large apertures to be installed on both sides of the ATLAS and CMS experiments. A dedicated cryostat design of about 1 m in diameter was developed for operation of these magnets at 1.9 K, comprising the required cryogenic circuits, interconnects, supports, insulation, and instrumentation systems. Six cryostats with various lengths in the range of 8 to 11 m are required on each side of the interaction points to house the triplet magnets, correctors and the first separation dipole. These cryostats will be linked through flexible interconnects to form a continuous vacuum insulation and cryogenic system of about 60 m in length. The second rearmost separation dipole requires a stand-alone cryostat of 15 m in length but nevertheless feature...
IEEE Transactions on Applied Superconductivity, 2022
As part of the U.S. contribution to the HL-LHC Accelerator Upgrade Project (AUP), Fermilab is des... more As part of the U.S. contribution to the HL-LHC Accelerator Upgrade Project (AUP), Fermilab is designing and building cold masses suitable for use in the LHC interaction regions. The cold mass provides a vacuum-tight helium enclosure for the magnets. Two magnets are aligned both axially and in cross section at Fermilab based on survey and warm magnetic measurements. Bus work and instrumentation is added. A welded stainless steel vacuum-tight shell surrounds the two magnets, and the structure is prepared for insertion into the cryostat. This paper summarizes the design of the cold mass including alignment, bus work, weld details, and instrumentation.
Chapter 11 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Lar... more Chapter 11 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity (rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology bey...
IEEE Transactions on Applied Superconductivity, 2016
The Large Hadron Collider (LHC) collimation system upgrade plan comprises new collimators in the ... more The Large Hadron Collider (LHC) collimation system upgrade plan comprises new collimators in the dispersion suppressors. The length required for each collimator along the LHC lattice is obtained by replacing an LHC main dipole and its cryostat with two shorter but stronger 11-T Nb3Sn magnets keeping the equivalent integrated field of the dipole removed. This requires a modification of the continuous cryostat, in order to create room-temperature beam vacuum sectors for the integration of the new collimators. In this paper, we present a new cryostat designed to allow the installation of a collimator between the 11-T magnets, while ensuring the continuity of the cryogenics, vacuum, and magnet powering systems of the LHC continuous cryostat. Challenging constraints, in terms of fabrication, alignment, and space, led to the development of a cryostat composed of three independent modules. Two of the modules house the 11-T dipole cold masses, which are cooled in the same 1.9-K pressurized superfluid helium bath of the main dipoles. These make use of the same design features of the LHC magnet cryostats, in order to contain construction and assembly costs and benefit from well-established procedures. A third module, which is placed between the two magnets, is equipped with cold to warm transitions on the beam lines and creates the space for the collimator between the vacuum vessel of the two 11-T magnet cryostats. The main functionalities, requirements, and implemented design solutions for this new cryostat are presented and discussed, in the context of the challenging integration in the LHC continuous cryostat and its tunnel.
IEEE Transactions on Applied Superconductivity, 2009
AbstractThe low-triplets of the Large Hadron Collider were designed and constructed by a world-w... more AbstractThe low-triplets of the Large Hadron Collider were designed and constructed by a world-wide collaboration officially formed in 1998. Over the course of the following years the col-laboration worked to produce the triplet components, including four 215 T/m, 70 mm ...
The insertion regions located around the four interaction points of the Large Hadron Collider (LH... more The insertion regions located around the four interaction points of the Large Hadron Collider (LHC) are mainly composed of the low-β triplets, the separation dipoles and their respective electrical feed-boxes (DFBX). The low-β triplets are Nb-Ti superconductor quadrupole magnets, which operate at 215 T/m in superfluid helium at a temperature of 1.9 K. The commissioning and the first operation of these components have been performed. The thermo-mechanical behavior of the low-β triplets and DFBX were studied. Cooling and control systems were tuned to optimize the cryogenic operation of the insertion regions. Hardware commissioning also permitted to test the system response. This paper summarizes the performance results and the lessons learned.
Integrating the large and complex LHC machine into the existing LEP tunnel is a major challenge. ... more Integrating the large and complex LHC machine into the existing LEP tunnel is a major challenge. Space was not really a problem to fit the LEP machine into its tunnel, but LHC cryostats are much larger than the LEP quadrupoles and the external cryogenic line fills even more the tunnel. Space problems lead to small clearances. Possible conflicts, or at least the most penalising ones, between installed equipment or with transport, must be solved beforehand in order to avoid unacceptable delays and extra costs during the installation. Experience gained with LEP has already shown the help that Computer-Aided Engineering tools could provide for the integration. A virtual model of the LHC is presently prepared. The actual LEP tunnel, known with a quite good accuracy (centimetre level), has been modelled and all the elements of the machine constructed as 3D objects with the CAD system are positioned accurately on the basis of data generated from the theoretical definition. These layouts ar...
INDIVIDUAL MAGNETS The optics flexibility of the LHC insertions is provided by the individually p... more INDIVIDUAL MAGNETS The optics flexibility of the LHC insertions is provided by the individually powered superconducting quadrupoles in the dispersion suppressors and matching sections. These cryo-magnets comprise special quadrupoles of the MQM and MQY type, and range in length from 5.4 m to 11.4 m. In total, 82 insertion quadrupoles will be assembled at CERN. In this paper we present the progress in fabrication and report on the performance of the first series quadrupoles. In particular, we present the quench performance of individual magnets and discuss the field quality trends and improvements based on magnet sorting. Quench training The quench history of the eight tested MQM magnets is
Following the incident in one of the main dipole circuits of the Large Hadron Collider (LHC) in S... more Following the incident in one of the main dipole circuits of the Large Hadron Collider (LHC) in September 2008, a detailed analysis of all magnet circuits has been performed by a dedicated task force. This analysis has revealed critical issues in the design of the 13 kA splices between the superconducting dipole and quadrupole magnets. These splices have to be consolidated before increasing the beam energy above 4 TeV and operating the LHC at 6.5-7 TeV per beam. The design of the consolidated 13 kA splices is complete and has been reviewed by an international committee of experts. Also, all other types of superconducting circuits have been thoroughly screened for potential safety issues and several important recommendations were established. They were critically assessed and the resulting actions are presented. In addition to the work on the 13 kA splices, other interventions will be performed during the first long shut-down of the LHC to consolidate globally all superconducting cir...
New low-β quadrupole magnets are being developed within the scope of the High Luminosity LHC (HL-... more New low-β quadrupole magnets are being developed within the scope of the High Luminosity LHC (HL-LHC) project in collaboration with the US LARP program. The aim of the HLLHC project is to study and implement machine upgrades necessary for increasing the luminosity of the LHC. The new quadrupoles, which are based on the Nb3Sn superconducting technology, will be installed in the LHC Interaction Regions and will have to generate a gradient of 140 T/m in a coil aperture of 150 mm. In this paper, we describe the design of the short model magnet support structure and discuss results of the detailed 3D numerical analysis performed in preparation for the first short model test.
To eliminate the risk of thermal runaways in LHC interconnections a consolidation by placing shun... more To eliminate the risk of thermal runaways in LHC interconnections a consolidation by placing shunts on the main bus bar interconnections is proposed by the Task Force Splices Consolidation. To validate the design two special SSS magnet spares are placed on a test bench in SM-18 to measure the interconnection in between with conditions as close as possible to the LHC conditions. Two dipole interconnections are instrumented and prepared with worst-case-conditions to study the thermo-electric stability limits. Two quadrupole interconnections are instrumented and prepared for studying the effect of current cycling on the mechanical stability of the consolidation design. All 4 shunted interconnections showed very stable behaviour, well beyond the LHC design current cycle.
IEEE Transactions on Applied Superconductivity, 2017
The high luminosity Large Hadron Collider (LHC) upgrade target is to increase the integrated lumi... more The high luminosity Large Hadron Collider (LHC) upgrade target is to increase the integrated luminosity by a factor 10, resulting in an integrated luminosity of 3000 fb -1 . One major improvement foreseen is the reduction of the beam size at the collision points. This requires the development of 150-mm single-aperture quadrupoles for the interaction regions. These quadrupoles are under development in a joint collaboration between CERN and the US-LHC Accelerator Research Program. The chosen approach for achieving a nominal quadrupole field gradient of 132.6 T/m is based on the Nb 3 Sn technology. The coils with a length of 7281 mm will be the longest Nb 3 Sn coils fabricated so far for accelerator magnets. The production of the long coils was launched in 2016 based on practise coils made from copper. This paper provides a status of the tooling development and production of the first copper coil, from winding, curing, and reaction heat treatment. In addition, an overview of the upcoming coil vacuum impregnation and the development of the magnet assembly including a prototype production schedule are provided.
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Papers by H. Prin