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International audience; In the framework of the HL-LHC project, a NbTi double aperture quadrupole magnet MQYY is being developed as an option to replace the LHC magnet MQY. This 90 mm double aperture cos-2θ quadrupole has an operating gradient of 120 T/m at 1.9 K. To demonstrate the validity of the design, a single aperture short model of 1.2 m called MQYYM has been developed. Designed by CEA and manufactured in collaboration with CERN, the MQYYM magnet is being prepared for cold test at CEA in a dedicated cryogenic station with LHe bath at 1 bar 4.2 K and 23 mbar 1.9 K. First, this paper will summarize the initial and as-built magnet designs based on the assembly at CERN. Second, updated mechanical measurements of collaring and axial pre-loading will be presented. Finally warm magnetic measurements performed at CERN during the assembly and at CEA during test preparation will be detailed.

The first series production of Nb3Sn Accelerator Magnets is approaching its end. The LHC dipole upgrade within the scope of the High Luminosity project consists of collared assemblies of 5.6 m-long coils targeted for a nominal field of 11 T at 11.85 kA and 60 mm aperture. As part of the quality control of the production, geometrical and magnetic measurements are performed at different steps. The experience gathered during manufacturing of 28 coils and 11 collared coils is summarized here. Using the available data, we analyzed the distributions of coil geometry, collared coil size, main field, and low order field errors in warm conditions. In some cases, the trends were traced back to displacements of the conductor with respect to the nominal layout. Three magneto-static conductor deformation models aim to explain the variability of field harmonics, confronted with measured data.

The recombination dipoles D2 (MBRD) for the luminosity upgrade of the Large Hadron Collider (LHC) are double aperture magnets to be placed on each side of ATLAS and CMS experiments, generating 4.5 T along a magnetic length of 7.78 m and a bore diameter of 105 mm. Its development plan foresees the construction of a short model 1.6 m long, followed by a prototype and by the series of 6 magnets. The magnet design was carried out at INFN Genova in a collaboration framework with CERN and the construction is ongoing in the industry (ASG Superconductors, Italy). The short model activities have just been accomplished after a successful power test performed at CERN, while the prototype is in its construction phase. In this contribution, the main features of the D2 magnet will be described, underlining the improvements implemented in the prototype with respect to the short model design. Then, the main results of the power test will be presented, focusing on training performance, protection scheme effectiveness and magnetic measurements.

The second prototype of the MCBXFB nested orbit corrector for the upgrade of the LHC has been manufactured at CIEMAT and assembled at CERN, in the framework of the HL-LHC project. This paper describes the changes introduced with respect to the first prototype in order to test some design improvements intended for the series magnets. The preload of the coils has been carefully studied, aiming to improve the performance in combined operation. A power test campaign has been carried out for this second prototype at CERN. Both dipoles reached ultimate current without any quench when individually powered. However, the results in combined operation did not improve those of the first prototype. Further analysis and studies are ongoing.

In a dipole or in a quadrupole accelerator magnet, the displacement of the coil turns induced by the electromagnetic forces can cause quenches limiting the magnet performance. For this reason, an azimuthal preload is applied to avoid azimuthal movements of the coil up to the required operational current. However, several tests showed that accelerator magnets can operate with a partial preload, i.e., that coil unloading during the ramp does not prevent reaching higher currents. This issue is particularly relevant for Nb 3 Sn magnets, where the loads applied to the Nb 3 Sn filaments can reach the degradation limits of critical current. In order to investigate the impact of coil preload on the quench performance, the MQXFS6 short model quadrupole for the High Luminosity Upgrade was tested under an azimuthal pre-load at 80% of the short sample current, reaching 93% of short sample current at 1.9 K. The preload was then released to 60%, still showing ability to operate in the range of 80--85% of short sample current as required by HL-LHC project. With this lower preload, the ability of going above 90% of short sample was lost, and a significant training appeared above 85%. When the preload was restored to the original 80% value, the magnet reached with few quenches 95% of short sample (13.4 T peak field). Magnetic measurements confirm the larger movement of the coil in the case with lower preload, and agree with finite element simulations. In a dipole or in a quadrupole accelerator magnet, the displacement of the coil turns induced by the electromagnetic forces can cause quenches limiting the magnet performance. For this reason, an azimuthal preload is applied to avoid azimuthal movements of the coil up to the required operational current. However, several tests showed that accelerator magnets can operate with a partial preload, i.e. that coil unloading during the ramp does not prevent reaching higher currents. This issue is particularly relevant for Nb$_3$Sn magnets, where the loads applied to the Nb$_3$Sn filaments can reach the degradation limits of critical current. In order to investigate the impact of coil preload on the quench performance, the MQXFS6 short model quadrupole for the High Luminosity Upgrade was tested under an azimuthal preload at 80% of the short sample current, reaching 93% of short sample current at 1.9 K. The preload was then released to 60%, still showing ability to operate in the range of 80-85% of short sample current as required by HL-LHC project. With this lower preload, the ability of going above 90% of short sample was lost, and a significant training appeared above 85%. When the preload was restored to the original 80% value, the magnet reached with few quenches 95% of short sample (13.4 T peak field). Magnetic measurements confirm the larger movement of the coil in the case with lower preload, and agree with finite element simulations. In a dipole or in a quadrupole accelerator magnet, the displacement of the coil turns induced by the electromagnetic forces can cause quenches limiting the magnet performance. For this reason, an azimuthal preload is applied to avoid azimuthal movements of the coil up to the required operational current. However, several tests showed that accelerator magnets can operate with a partial preload, i.e. that coil unloading during the ramp does not prevent reaching higher currents. This issue is particularly relevant for Nb$_3$Sn magnets, where the loads applied to the Nb$_3$Sn filaments can reach the degradation limits of critical current. In order to investigate the impact of coil preload on the quench performance, the MQXFS6 short model quadrupole for the High Luminosity Upgrade was tested under an azimuthal preload at 80% of the short sample current, reaching 93% of short sample current at 1.9 K. The preload was then released to 60%, still showing ability to operate in the range of 80-85% of short sample current as required by HL-LHC project. With this lower preload, the ability of going above 90% of short sample was lost, and a significant training appeared above 85%. When the preload was restored to the original 80% value, the magnet reached with few quenches 95% of short sample (13.4 T peak field). Magnetic measurements confirm the larger movement of the coil in the case with lower preload, and agree with finite element simulations.

In the context of CERN's high-luminosity upgrade project (HL-LHC) for the Large Hadron Collider (LHC), a new double aperture beam orbit corrector magnets will be installed near the recombination dipole (D2). These 2.2 m long NbTi dipoles are built with the canted cosine theta (CCT) technique. The two independently powered apertures are oriented such that their field vectors are perpendicular to each other and to the direction of the beams. A full-length double aperture prototype was built and tested at CERN in the SM18 test facility. Here we present the results of powering tests at 1.9 and 4.5 K: training of each aperture, magnetic field quality and cross-talk effects, quench detection system effectiveness, quench protection performance and quench-back with several energy extraction systems.

The first prototype of the short orbit corrector for the upgrade of the LHC has been fabricated at CIEMAT, in collaboration with CERN, in the framework of the HL-LHC project. It consists of two nested dipoles, with an aperture of 150 mm and physical length of 1.5 m. A first power test was performed without the outer dipole coils, which were replaced by a support structure to align the iron yoke with the collared inner dipole. This test was aimed to validate the coil fabrication techniques, which are innovative for a NbTi Rutherford cable. In the power test of the full assembled magnet, individual training of both dipoles was fine to ultimate current. However, the magnet was not able to reach nominal torque in combined operation. Several power tests and re-assemblies were necessary to be able to power both dipoles till nominal current. This paper describes the test results and analysis of the measurements. The magnet is heavily instrumented with voltage taps, collars with strain gauges and bullet gauges at the axial pushers.

In the framework of the High-Luminosity Large Hadron Collider (HL-LHC) project, larger and shielded beam screens will be installed in the beam pipe of the superconducting magnets of the insertion next to the ATLAS and CMS detectors. The beam screen is a complex assembly that guarantees the vacuum requirements while shielding the magnet cold mass from the induced heat loads. Such an assembly has to withstand high intensity electromagnetic forces induced during magnet quenches. The mechanical stability was verified in a dedicated quench test campaign performed at the magnet test station of CERN. Strain gauges, custom-made probes, and optical fibers were installed in the beam screen to measure deformations during a quench. Magnetic field measurements were also carried out by means of pick-up coils mounted within the assembly. The main outcomes of this work are the elastic behaviour of the beam screen after 52 quenches and a satisfactory agreement between measurements and simulations.

Author(s): Mangiarotti, F; Bajas, H; Ambrosio, G; Bajko, M; Bordini, B; Bourcey, N; Duda, M; Desbiolles, V; Feuvrier, J; Fleiter, J; Bermudez, SI; Chiuchiolo, A; Devred, A; Ferracin, P; Fiscarelli, L; Mentink, M; Nobrega, A; Pepitone, K; Ravaioli, E; Schmalzle, J; Todesco, E; Perez, JC; Vallone, G; Willering, G; Yu, M | Abstract: For the high luminosity upgrade of the CERN large hadron collider, lower β∗ quadrupole magnets based on advanced Nb3Sn conductors will be installed on each side of the ATLAS and compact muon solenoid (CMS) experiment insertion zones. As part of the technological developments needed to achieve the required field gradient of 132.6 T/m within a 150-mm aperture, short length model magnets, named MQXFS, are tested both at the CERN SM18 and Fermilab test facilities. The model magnets rely on two types of Nb3Sn conductors (restack rod process (RRP) and powder-in-tube (PIT)) and on an innovative bladders and keys design to provide mechanical support against the Lorentz forces. In 2016 and 2017, the powering tests of the first two models MQXFS3 (RRP) and MQXFS5 (PIT) proved that nominal performance (16.5 kA) could be reached with excellent memory of the quench current after thermal cycle. However both magnets showed a slow training behavior with clear observations of voltage disturbances before the quench. Besides, only MQXFS5 could reach ultimate current (17.9 kA) whereas erratic behavior was observed on MQXFS3 due to conductor local degradation at the head of one of the coils. In 2018, this limiting coil was changed and the applied azimuthal prestress increased. While ultimate current could then be reached, no stable current could be maintained due to identified defect on the outer layer of the new coil. Finally the outcome of the test of the new model MQXFS4, featuring the final RRP conductors that will be used for the series production and variation on the inner layer quench heater designs are here reported in details.

In the frame of the high-luminosity upgrade project for the large hadron collider, new twin aperture beam orbit corrector magnets will be installed near the recombination dipole (D2). These magnets are 2.2 m long canted cosine theta NbTi dipoles, with two independently powered apertures oriented such that their field vectors are perpendicular to each other and to the direction of the beams. A 0.5 m model magnet in single and double aperture configuration and a full-length double aperture prototype were built and tested at CERN. In this paper, the performance of these magnets at 1.9 K in terms of training behavior, quench detection and protection, and other tests is discussed. In addition, the thermal response of the magnet to a hypothetical beam discharge is simulated and analyzed.

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). The US Hilumi-LHC Accelerator Upgrade (HL-LHC AUP) and CERN are jointly developing a 150 mm aperture Nb3Sn magnet. Due to the large beam size and orbit displacement in the final focusing triplet, MQXF has challenging field quality targets at collision energy. Magnetic measurements have been performed both at ambient and cryogenic temperatures in the four short models built and tested. This paper presents the magnetic analysis, comparing field measurements with the expectations and the field quality requirements. The analysis is focused on the geometrical harmonics and iron saturation effect, including three dimensional effects and transfer function repeatability. Persistent currents and dynamic effects are also discussed. 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). The U.S. HiLumi-LHC Accelerator Upgrade and CERN are jointly developing a 150-mm aperture Nb3Sn magnet. Due to the large beam size and orbit displacement in the final focusing triplet, MQXF has challenging field quality targets at collision energy. Magnetic measurements have been performed both at ambient and cryogenic temperatures in the four short models that were built and tested. This paper presents the magnetic analysis, comparing field measurements with the expectations and the field quality requirements. The analysis is focused on the geometrical harmonics and iron saturation effect, including three-dimensional effects and transfer function repeatability. Persistent currents and dynamic effects are also discussed.

The National Institute for Nuclear Physics (INFN) is developing, at the Laboratory of Accelerators and Applied Superconductivity (LASA Milan, Italy), five families of corrector magnets, from skew quadrupole up to dodecapole order, which will be installed in the interaction regions of the High-Luminosity Large Hadron Collider (LHC). These magnets are based on a superferric design, which allows a relatively simple, compact and easy-to-construct magnets. This activity takes place within the framework of a collaboration agreement between CERN and INFN. The magnets have been designed and prototype units have been built and tested for the sextupole, octupole, and decapole orders. Magnetic measurements have been performed in order to characterize the field quality, and to validate the design and construction. This paper presents the instruments and the approach for the magnetic measurements on the prototype magnets. Moreover, the results of measurements at cryogenic temperature, up to the nominal field level, are reported. The magnetic field quality, in terms of transfer function and field multipoles, is analysed as function of the excitation level. The iron saturation effects, which are a major concern of the selected design, are compared with the 3-D magnetic calculations and discussed in view of the construction of the series magnets to be integrated in the corrector package assembly.

The High Luminosity Large Hadron Collider (HL-LHC) is the new flagship project of CERN. First endorsed in 2013 and approved in 2016, HL-LHC is an upgrade of the accelerator aiming to increase by a factor of ten the statistics of the LHC collisions at the horizon of 2035–2040. HL-LHC relies on cutting edge technologies: among them, large aperture superconducting magnets will replace the present hardware to allow a smaller beam size in two interaction points (IPs). The project involves the construction of about 150 magnets of six different types: the quadrupole triplet, two main dipoles and three orbit correctors. The triplet, manufactured at CERN and in the USA, will consist of 30 magnets based on Nb3Sn technology, with an operational peak field of 11.4 T. These will be the first quadrupole Nb3Sn magnets installed in a particle accelerator. The other five types of magnets, all relying on Nb–Ti technology, present non-trivial challenges in the design and construction; they will be manufactured as part of in-kind contribution under the responsibility of institutes in Japan, China, Spain, and Italy. The project is now in the phase of transition between qualification through short models and prototypes and the beginning of the series construction. In this paper we review the magnet requirements, the reasons for selecting the design, the technological challenges with respect to previous projects, and we summarize the steps that have been taken to validate the baseline.

IEEE transactions on magnetics 57(2), 6100105 (2021). doi:10.1109/TMAG.2020.3005722, Published by IEEE, New York, NY

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 Nb3Sn 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.

Journal of sensors and sensor systems : JSSS 9(1), 99-107 (2020). doi:10.5194/jsss-9-99-2020, Published by Copernicus Publ., Göttingen

In the framework of the high-luminosity upgrade of the large hadron collider, the U.S. LARP collaboration and CERN are jointly developing a 150-mm aperture Nb3Sn quadrupole for the Large Hadron Collider (LHC) interaction regions. Due to the large beam size and orbit displacement in the final focusing triplet, MQXF has challenging targets for field quality at nominal operation conditions. Three short model magnets have been tested and around 30 coils have been built, allowing a first analysis of the reproducibility of the coil size and turns positioning. The impact of the coil shimming on field quality is evaluated, with special emphasis on the warm magnetic measurements and the correlation to field measurements at cold and nominal field. The variability of the field harmonics along the magnet axis is studied by means of a Monte-Carlo analysis and the effects of the corrective actions implemented to suppress the low-order unallowed multipoles are discussed.

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 Nb3Sn 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 by-pass 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.

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). CERN and LARP are currently collaborating to develop a 150-mm-aperture quadrupole based on Nb $_3$ Sn superconducting cables for the coils, and an aluminum shell with the bladder-key technology for the support structure. This paper presents the test setup for magnetic measurements, both at ambient and cryogenic temperatures, and the instrumentation being used for the first two short-models of MQXF built and tested at CERN. Finally, the measurement results, in terms of field quality, effects of persistent currents, and iron saturation are reported and discussed.

For the upgrade of the LHC, two 15-m NbTi main dipole magnets are foreseen to be replaced by two 11 T 5.7-m-long Nb 3Sn dipoles each. A series of model magnets has been produced to verify the design choices that are important for the prototype and series production, focusing on mechanical aspects and protection studies. A fourth and a fifth 2-m single aperture models were produced, assembled, and tested. In this paper, the cold powering tests of the single aperture models SP104 and SP105 will be presented and the results will be compared with the previous models. Special attention will be given to the upper limit in magnet current due to quenches in the midplane turns.

In the framework of the High-Luminosity Large Hadron Collider, the installation of a new generation of quadrupole magnets is foreseen on each side of ATLAS and CMS experiments. The new magnets are based on Nb3Sn technology and shall be able to reach an ultimate current of 17.9 kA with a peak field of 12.3 T in the coil. In 2016 and 2017, the first two short models, called MQXFS3 and MQXFS5, have been tested at 4.2 and 1.9 K in the two new test benches at the European Organization for Nuclear Research. This paper presents the result of the quench performance of the two models; the first magnet reached nominal but failed to reach ultimate, showing detraining in one coil. MQXFS5 reached ultimate performance without any detraining phenomena, validating the PIT conductor used for the first time in this magnet program.

For the upgrade of the LHC during the long shutdown 2 and for the HL-LHC upgrade during the long shutdown 3, a few 15 m 8.3 T Nb–Ti main dipole magnets are foreseen to be replaced by two 11 T Nb3Sn dipoles, 5.5 m long each. After the production and test of three single aperture models at CERN, the first 2-m-long twin-aperture model has been tested. The model was used to exploit the limits of the model in terms of quench performance and protection. The protection studies included the heater efficiency studies and hotspot temperature studies. In this paper, the performance of the magnet DP101 in terms of training behavior, detection, and protection, and other cold powering test will be presented and discussed.

The high-luminosity large hadron collider (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 such as 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 toward the production for the long shut down 2 is described.

Extracting the coefficients of Fourier-Bessel series, known as pseudo-multipoles or generalized gradients, from magnetic measurements of accelerator magnets involves technical and mathematical challenges. First, a novel design of a short, rotating-coil magnetometer is required that does not intercept any axial field component of the magnet. Moreover, displacing short magnetometers, step-by-step along the magnet axis, yields a convolution of the local multipole field errors and the sensitivity (test function) of the induction coil. The deconvolution must then content with the low signal-to-noise ratio of the measurands, which are integrated voltages corresponding to spatial flux distributions. Finally, the compensation schemes, as implemented on long coils used for measuring the integrated field harmonics, cannot be applied to short magnetometers. All this requires careful design of experiment to derive the optimal length of the induction coil, the step size of the scan, and the highest order of pseudo-multipoles in the field reconstruction. This paper presents the theory of the measurement method, the data acquisition and deconvolution, and the design and production of a saddle-shaped, rotating-coil magnetometer., Proceedings of the 13th Int. Computational Accelerator Physics Conf., ICAP2018, Key West, FL, USA

This chapter describes the design of, and parameters for, the 11 T dipole developed at the European Organization for Nuclear Research (CERN) for the High Luminosity Large Hadron Collider (HL-LHC) project. The results for testing the short models as well as the first 5 m long magnet are also presented. Finally, the production process for the six units, of which four are to be installed in the HL-LHC, is described, with a description of the process for planning the installation. In 2020, these dipoles should be the first Nb3Sn magnets working in an accelerator.

For the upgrade of the LHC in LS2 and for the High Luminosity upgrade in LS3, a few 15-m Nb–Ti main dipole magnets are foreseen to be replaced by two 5.5-m-long Nb3Sn dipoles each. After a series of dipole models produced and tested by the collaborating partners at FNAL, in 2014 and 2015, the first short dipole model magnets have been produced and tested at CERN in a single aperture configuration. In this paper, the test results and test analyses will be discussed with a focus on training and cold powering performance.

The high-luminosity upgrade for the LHC (HL-LHC) envisages the replacement of some 15-m-long NbTi dipoles in the dispersion suppressor area by shorter Nb3Sn magnets with a nominal field of 11 T. The new magnets must be compatible with the lattice and other main systems of the LHC. The shorter length of new units will allow the installation of collimators. The successful use of the Nb3Sn technology requires an intense R&D program, and therefore, a CERN–Fermilab joint development program was established. This paper describes the magnetic measurement procedure and presents the analysis of the magnetic measurements on the first 2-m-long single-aperture demonstrators built and tested at CERN. The geometrical field multipoles, the iron saturation effects, and 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 requirements for machine operation.

The rotating search coil is a precise and widely used tool for measuring the magnetic field harmonics of accelerator magnets. This paper deals with combining several such multipole measurements, in order to cover magnet apertures largely exceeding the diameter of the available search coil. The method relies on the scaling laws for multipole coefficients and on the method of analytic continuation along zero-homotopic paths. By acquiring several measurements of the integrated magnetic flux density at different transverse positions within the bore of the accelerator magnet, the uncertainty on the field harmonics can be reduced at the expense of tight tolerances on the positioning. These positioning tolerances can be kept under control by mounting the rotating coil and its motor-drive unit on precision alignment stages. Therefore, the proposed technique is able to yield even more precise results for the higher-order field components than a dedicated rotating search coil of larger diameter. Moreover, the versatility of the measurement bench is enhanced by avoiding the construction of rotating search coils of different measurement radii.

In the frame of the high-luminosity upgrade project (HL-LHC) at CERN, a double aperture, independently powered, family of beam orbit corrector magnets will be installed close to the two main LHC experiments Atlas and CMS. These 2.6 T magnets, built using a canted cos-theta design. This paper describes the development of the prototype, full size 2-m-long magnets. We first focus on design and assembly techniques: from coil winding using a CNC machined aluminium former to impregnation, layer-jump, quench protection, and yoke assembly. We then present the power test results at 1.9 K: training, field quality and protection.

International audience; In the context of the HL-LHC project, a NbTi double aperture quadrupole magnet called MQYY is being developed. This 90-mm-aperture quadrupole magnet has a magnetic length of 3.67 m and an operating gradient of 120 T/m at 1.9 K. Its development is done along two parallel paths: 1) the design, fabrication, and test of a short model; 2) the design and fabrication of two full-scale prototypes in industry within the H2020 EU Pre-Commercial Procurement project QUACO implemented by CERN, CEA, CIEMAT, and NCBJ. We report here on the short-model design choices the status of its fabrication and the preparation of the tests. In particular, we describe the magnetic and mechanical design relying on self-supporting collars, the protection aspects, the fabrication, and the cold test preparation. Finally, we present the unusual scheme of the QUACO project leading to the prototypes fabrication.

In an effort to develop economical magnets for an upgrade of the LHC injector complex, CERN started an R&D program on superconducting Fast Cycled Magnets (FCM) in 2009. One of the challenges in this program was to develop a test station, which started working in summer 2012 when the FCM dipole demonstrator was tested. The magnet contains several important features, like forced-flow cooling of supercritical He and it has a protection scheme based direct voltage measurement with co-wound voltage tap wires. In this paper we report on the cryogenic and powering requirements and operation, the quench protection system, the temperature and mechanical measurements. The functioning of the test station and instrumentation are evaluated and we will discuss the measurements on a detailed level.

FNAL and CERN are carrying out a joint R&D program with the goal of building a 5.5-m-long twin-aperture 11-T Nb3Sn dipole prototype that is suitable for installation in the LHC. An important part of the program is the development and test of a series of short single-aperture and twin-aperture dipole models with a nominal field of 11 T at the LHC operation current of 11.85 kA and 20% margin. This paper presents the results of magnetic measurements of a 1-m-long single-aperture Nb3Sn dipole model fabricated and tested recently at FNAL, including geometrical field harmonics and effects of coil magnetization and iron yoke saturation.

Author(s): Izquierdo Bermudez, S; Nilsson, E; Bottura, L; Bourcey, N; Devred, A; Ferracin, P; Ferradas Troitino, S; Fiscarelli, L; Guinchard, M; Loffler, C; Mazet, J; Perez, JC; Prin, H; Savary, F; Sequeira Tavares, S; Vallone, G; Willering, G | Abstract: For the Large Hadron Collider luminosity upgrade, two of the NbTi 8.3 T main bending dipoles will be replaced by two shorter Nb3Sn 11.2 T dipoles to create space for the installation of collimators in the dispersion suppression region. With the aim to verify the design features, several 2 m long 11 T models have been constructed and tested at CERN. During the fabrication and assembly of, so far, seven single and two double aperture short model magnets, several challenges were identified and tackled. These include reproducibility in coil fabrication and assembly procedure, as well as control of mechanical stresses in the conductor and surrounding structure. In order to limit coil over-compression and improve reproducibility, the cable insulation was re-optimized. In addition, a review of the collaring procedure of the 11 T magnet was launched with the goal of reducing the risk of conductor degradation due to excessive stress. In this paper, the main fabrication and assembly steps are described, including the description of the actions taken to resolve the identified weakness.

A measurement-domain-specific language, which is based on a model-driven paradigm for measurement-test-procedure definition, instrument configurations, and task synchronization, is proposed. This formal language, which is particular for a specific measurement field, aims at specifying complete, easy-to-understand, easy-to-reuse, and easy-to-maintain applications efficiently and quickly by means of a script. The script is checked and integrated into the existing software framework automatically by a specific parser-builder chain, in order to produce the measurement application. Constructs for abstracting key concepts of the domain allow the test engineer to write more concise and higher level programs by natural language-like sentences in a shorter time without being a skilled programmer. As an experimental case study, the proposed language has been applied to the flexible framework for magnetic measurements at the European Organization for Nuclear Research (CERN).

A framework for easily developing software for measurement and test applications under highly and fast-varying requirements is proposed. The framework allows the software quality, in terms of flexibility, usability, and maintainability, to be maximized. Furthermore, the development effort is reduced and finalized, by relieving the test engineer of development details. The framework can be configured for satisfying a large set of measurement applications in a generic field for an industrial test division, a test laboratory, or a research center. As an experimental case study, the design, the implementation, and the assessment inside the application to a measurement scenario of magnet testing at the European Organization for Nuclear Research is reported.

A system for the active compensation of magnetic field errors within ±2 ppm relative to the main field in superconducting magnets is proposed. A high-performance rotating coils system is exploited in order to combine high time resolution and integral field measurements. The compensation is based on an enhanced characterization of the corrector magnets and the measured field: this allows the system to be used as off-line reference in accelerator facilities. As an experimental case study, the measurement system and the procedure for compensating field errors of dipole magnets of the Large Hadron Collider at the European Organization for Nuclear Research (CERN) are illustrated.

A Petri net (PN)-based approach to software synchronization in automatic measurement systems is proposed. Tasks are synchronized by means of a PN modeling an execution graph, where nodes represent tasks and arrows among nodes point out time succession among the corresponding tasks. This allows software synchronization to be abstracted above the code level by leaving the test engineer to work at a more intuitive level. As an experimental case study, the design, the implementation, and the application to a measurement scenario of the PN-based synchronizer inside the software framework for testing magnets at the European Organization for Nuclear Research (CERN) are illustrated.

An accurate and flexible system for magnetic permeability measurements is described. In particular, effects such as eddy currents and signal drift are minimized by exploiting the main system features: (i) high-performance digital integration by means of a digital integrator, with a theoretical resolution of 10 ppt using an 18-Bit A/D Converter at 800 kS/s, specifically developed for magnetic measurements, and (ii) flexibility of the measurement procedure for overcoming magnetic field non-uniformity errors through a procedure specifically generated by means of a flexible software framework. In particular, the theoretical background underlying the measurement, the procedure, and the system architecture are illustrated, as well as experimental results from testing a nonoriented steel are described. © 2010 IEEE.

One of the main requirements for the operations of the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is a suitable correction of multipole errors in magnetic field. The feed-forward control of the LHC is based on the Field Description for the LHC (FiDel), capable of forecasting the magnet's behavior in order to generate adequate current ramps for main and corrector magnets. Magnetic measurements campaigns aimed at validating the model underlying FiDel highlighted the need for improving the harmonic compensation of the third-harmonic (b 3 ) component of the main LHC dipoles. In this paper, the results of a new measurement campaign for b 3 harmonic compensation, carried out through the new Fast Acquisition Measurement Equipment (FAME), are reported. In particular, the mechanism and the measurement procedure of the compensation, as well as the new perspectives opened by preliminary experimental results, are illustrated.

Advanced User Interface Generation in the Software Framework for Magnetic Measurements at CernA model-based approach, the Model-View-Interactor Paradigm, for automatic generation of user interfaces in software frameworks for measurement systems is proposed. The Model-View-Interactor Paradigm is focused on the "interaction" typical in a software framework for measurement applications: the final user interacts with the automatic measurement system executing a suitable high-level script previously written by a test engineer. According to the main design goal of frameworks, the proposed approach allows the user interfaces to be separated easily from the application logic for enhancing the flexibility and reusability of the software. As a practical case study, this approach has been applied to the flexible software framework for magnetic measurements at the European Organization for Nuclear research (CERN). In particular, experimental results about the scenario of permeability measurements are reported.

A Measurement-Domain Specific Language (MDSL) for test procedure definition, measurement tasks synchronization, and instrument configuration is proposed. MDSL is a formal language specially designed for a specific domain of measurement and test, aimed at specifying complete, easy-to-understand, -reuse, and -maintain applications efficiently and quickly. Owing to MDSL constructs capability of abstracting key concepts of the domain, the test engineer can write more concise and higher level programs in shorter time without being a skilled programmer. The MDSL has been applied to the specifications of superconducting magnet tests of the Large Hadron Collider at CERN. © 2009 IEEE.

The fast digital integrator has been conceived to face most demanding magnet test requirements with a resolution of 10 ppm, a signal-to-noise ratio of 105 dB at 20 kHz, a time resolution of 50 ns, an offset of 10 ppm, and on-line processing. In this paper, the on-field achievements of the fast digital integrator are assessed by a specific measurement campaign at the European Organization for Nuclear Research (CERN). At first, the architecture and the metrological specifications of the instrument are reported. Then, the recent on-field achievements of (i) ±10 ppm of uncertainty in the measurement of the main field for superconducting magnets characterization, (ii) ±0.02 % of field uncertainty in quality assessment of small-aperture permanent magnets, and (iii) ±0.15 % of drift, in an excitation current measurement of 600 s under cryogenic conditions, are presented and discussed.