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In the framework of the High-Luminosity Large HadronCollider, 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. [ABSTRACT FROM AUTHOR]

The Canted-Cosine-Theta is a design option for the next generation of high field superconducting dipoles being pursued within the US Magnet Development Program. This paper presents new modeling techniques developed for design and analysis of CCT magnets. For mechanical modeling in ANSYS, three approaches with increasing accuracy are compared: 2-D symmetry models; 3-D periodic symmetry models; and full 3-D models. Methods for the static and transient magnetic simulation using ANSYS are presented with a focus on circuit-coupled models for predicting magnet behavior following quench. Where applicable, simulation results are compared to data from CCT magnet tests at Berkeley. [ABSTRACT FROM AUTHOR]

The high luminosity upgrade project U.S. LARP/HiLumi has successfully tested the first 1.5 m prototype quadrupole MQXFS1 at Fermilab' Magnet test facility. Several thermal cycles and test programs were performed, with different preload configurations. To localize and characterize quenches, a quench antenna and voltage taps are used. The quench antenna was placed inside a warm bore of an anticryostat centered in the magnet. We varied the length between quench antenna segments from 2.54 to 15.24 cm, and shifted the location of the antenna to localize the quench origin along the various wedge and spacers transitions in the lead end of the magnet. We present results on the identified quench locations for the second and third thermal cycle in this paper. [ABSTRACT FROM AUTHOR]

A multilayer high field dipole magnet has been designed for future particle accelerators. The magnet has eight layers of a \Nb3\Sn outsert coil and four layers of a Bi-2212 insert coil (see Figs. 1 and 2). The layers are graded, delivering a short-sample field of 17.7 T in a 40-mm bore. The coil layers are of a canted cosine–theta design—with ribs and spars that guide and support the coil windings, shape the field, intercept Lorentz forces, and minimize conductor prestress. We present a general overview of the concept and report on the magnetic and mechanical design including an initial cost estimate and construction plan. [ABSTRACT FROM PUBLISHER]

We report test results for the one meter long dipole HD3b, a block-type accelerator quality \Nb3\Sn magnet built at LBNL with operational bore fields in the range of 13–15 T. The magnet is an upgrade of the previously reported HD2 and HD3a versions, with several modifications implemented to improve conductor positioning, reduce cable “hard-way” bending radius, and strengthen electrical insulation between cables and coil parts. The magnet exhibited long training behavior, but showed a good “memory” of the trained state upon thermal cycling. Ramp-rate dependence of the quench current, field quality performance characteristics, and protection heater studies were conducted. Quench propagation velocity and quench locations were determined based on the voltage signals; quench localization was further improved using inductive quench antenna and acoustic emission sensors. Short- and long-term acoustic precursors to quenching were observed. [ABSTRACT FROM PUBLISHER]

The U.S. LHC Accelerator Research Program has been developing \Nb3\Sn quadrupole magnets of progressively increasing performance and complexity for the High-Luminosity LHC project. The magnets are wound with Rutherford cables following the wind-and-react process. The resulting inter-strand coupling can generate strong field distortions during current ramp. The latest series of 120 mm aperture magnets (HQ) are designed and built for high field quality, offering an opportunity for detailed studies of these effects. Magnetic measurements of first-generation HQ magnets showed strong ramp-rate dependence. A stainless-steel core was introduced for the second generation of magnet coils to control the inter-strand coupling currents and the resulting dynamic multipoles. We report the observed dynamic effects and compare with calculations taking into account the coil geometry and cross-contact resistance in the Rutherford cable. In particular, the dependence of field quality on width and position of the stainless steel core is discussed. [ABSTRACT FROM PUBLISHER]

In the framework of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) project, the US LHC accelerator research program is developing high-gradient, large-aperture \Nb3 \Sn quadrupole magnets for the LHC interaction regions. The fabrication and tests of a first series of 120-mm-aperture “HQ01” coils revealed design issues that resulted in limited performance. A second series of coils was fabricated in which a number of improved features were implemented (HQ02 coils). The improvements were partly validated with the successful test of an HQ02 coil in a mirror structure, which reached 97% of the short sample. Here, we review the modifications in the coil design and the coil fabrication process, report the issues met during the fabrication, give details of the few differences that exist within the set of HQ02 coils, and discuss a list of further improvements that will be implemented in a third series of HQ coils. [ABSTRACT FROM PUBLISHER]

We report quench test results for the 1-meter long, 120 mm aperture Nb3Sn quadrupole magnet, HQ01, designed, fabricated and tested for the LHC Accelerator Research Program (LARP). The magnet has a design gradient of 219 T/m at 1.9 K and peak field of \sim15 T. Earlier tests (HQ01a, b) showed peak gradients of 152 T/m at 4.4 K but also revealed electrical insulation weaknesses that ultimately led to coil damage. Structural and electrical improvements incorporated into HQ01c magnet have assured and tracked the electrical integrity of the coils. The most recent HQ01d and HQ01e tests demonstrated gradients of 170 T/m at 4.4 K (86% of short sample critical current) with moderate training. By analyzing magnet voltage test data, quench propagation velocities and quench locations were determined. Most of the quenches tended to cluster around the pole region of the coils. Eight PC-board quench antennas were installed to better identify quench locations. We monitored longitudinal propagation of pole-turn quenches and correlated inductive responses of the quench antennas with magnet voltages. On down-ramps, the HQ magnet exhibited no quenches at rates up 150 A/s; the experimental ramp-rate dependence was analyzed using a simple ‘loss model’. [ABSTRACT FROM PUBLISHER]

In the past two years the US LARP program carried out five tests on a quadrupole magnet aimed at the high luminosity upgrade of Large Hadron Collider (HiLumi-LHC). The 1-meter long, 120 mm bore \ Nb3{\ {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 is part of the US LHC Accelerator Research Program (LARP). In a series of tests, carried out at 4.4 K, the magnet reached a maximum “short-sample” performance of 86%. The tests exposed several shortcomings that are now being addressed in a Research & Development program. This paper summarizes the magnet test results, reveals findings, R&D actions and future improvements. [ABSTRACT FROM PUBLISHER]

In order to continue supporting the development of accelerator magnets for the next generation of particle colliders, the LBNL Superconducting Magnet Program has started the design and fabrication of the Nb3Sn Large-aperture Dipole LD1. The goal of the magnet is to generate a dipole field of 13 T to 15 T in a clear aperture of 144 mm \times 94 mm, enabling high-field tests of Rutherford cables and insert coils made of Nb3Sn or high temperature superconductors (HTS), like Bi-2212, YBCO, and Bi-2223. The bore size will also accommodate large Cable-In-Conduit Conductors (CICC's), including ITER cables. We describe in this paper the design of LD1, in particular cable geometry, coil lay-out and support structure. Operational conditions based on strand measurements will be discussed, focusing on coil peak fields in straight section and end region, bore field homogeneity, and stress on the conductor during assembly, cool-down and excitation. [ABSTRACT FROM PUBLISHER]

HQ01 is a superconducting quadrupole magnet under development by the LHC Accelerator Research Program (LARP) as a part of an R&D effort to demonstrate that Nb3Sn magnet technology is a viable option for a future luminosity upgrade of the LHC. The design is characterized by a 120 mm bore, a maximum gradient of 219 T/m at 1.9 K, and a support structure based on an aluminum shell pre-tensioned by water-pressurized bladders. The shell-based structure concept has already been successfully implemented in previous LARP quadrupole magnets. In HQ01, the structure incorporates additional features designed to provide full alignment between the support structure components and the coils. Specifically, the coil azimuthal alignment is achieved through outer layer pole keys which, by intercepting part of the force applied by bladders and shell, remain clamped to bolted aluminum collars from assembly to full excitation. A sequence of assemblies and cool-downs were executed with different keys sizes to characterize the alignment system and its impact on coil pre-load, at both room temperature and at 4.5 K. This paper reports on the mechanical behavior of the HQ01, by summarizing the strain gauge data and comparing them with FEM model predictions. [ABSTRACT FROM PUBLISHER]