Luca Gentini

Accelerator-Quality HTS Dipole Magnet Demonstrator Designs for the EuCARD-2 5-T 40-mm Clear Aperture Magnet

Future high-energy accelerators will need very high magnetic fields in the range of 20 T. The Enhanced European Coordination for Accelerator Research and Development (EuCARD-2) Work Package 10 is a collaborative push to take high-temperature superconductor (HTS) materials into an accelerator-quality demonstrator magnet. The demonstrator will produce 5 T stand alone and between 17 and 20 T when inserted into the 100-mm aperture of a Fresca-2 high-field outsert magnet. The HTS magnet will demonstrate the field strength and the field quality that can be achieved. An effective quench detection and protection system will have to be developed to operate with the HTS superconducting materials. This paper presents a ReBCO magnet design using a multistrand Roebel cable that develops a stand-alone field of 5 T in a 40-mm clear aperture and discusses the challenges associated with a good field quality using this type of material. A selection of magnet designs is presented as the result of the first phase of development.

submitter : First Cold Powering Test of REBCO Roebel Wound Coil for the EuCARD2 Future Magnet Development Project

EuCARD-2 is a project partly supported by FP7-European Commission aiming at exploring accelerator magnet technology for 20 T dipole operating field. The EuCARD-2 collaboration is liaising with similar programs for high field magnets in the USA and Japan. EuCARD-2 focuses, through the work-package 10 “Future magnets,” on the development of a 10 kA-class superconducting, high current density cable suitable for accelerator magnets, for a 5 T stand-alone dipole of 40 mm bore and about 1 m length. After standalone testing, the magnet will possibly be inserted in a large bore background dipole, to be tested at a peak field up to 18 T. This paper starts by reporting on a few of the highlight simulations that demonstrate the progress made in predicting: dynamic current distribution and influence on field quality, complex quench propagation between tapes, and minimum quench energy in the multitape cable. The multiphysics output importantly helps predicting quench signals and guides the development of the novel early detection systems. Knowing current position within individual tapes of each cable we present stress distribution throughout the coils. We report on the development of the mechanical component and assembly processes selected for Feather-M2 the 5 T EuCARD2 magnet. We describe the CERN variable temperature flowing helium cold gas test system. We describe the parallel integration of the FPGA early quench detection system, using pickup coils and temperature sensors, alongside the standard CERN magnet quench detection system using voltage taps. Finally we report on the first cold tests of the REBCO 10 kA class Roebel subscale coil named Feather-M0.

Integration of the 11-T Nb3Sn Dipoles and Collimators in the LHC

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.

Hi-Lumi LHC Twin-Aperture Orbit Correctors Magnet System Optimisation

The large hadron collider (LHC) upgrade, called high luminosity LHC (HL-LHC) is planned for the next decade. A wide range of magnets and new technologies are currently under development.xa0 One of these systems will be a set of twin-aperture beam orbit correctors positioned on the approaches to the ATLAS and CMS experiments. This twin-aperture magnet system comprising 16 magnets, approximately 2 m long, with large 105xa0mm clear aperture coils. Each aperture will independently deliver 5 T·m integral field, between apertures the field vectors are rotated by 90° from each other, individually powered, crosstalk between apertures is controlled to give good field quality independent of aperture powering status. This paper presents the sequence of magnet optimisations performed that determine optimal coil geometry for the canted cosine theta coil design, to achieve good field quality between the individually powered large apertures, quench optimization, integration of the magnet with the adjacent magnetic objects, and radiation hard robust design. Finally the design focuses on low system cost with minimal tooling.

submitter : Hi-Lumi LHC Twin Aperture Orbit Correctors 0.5-m Model Magnet Development and Cold Test

The large hadron collider (LHC) upgrade, called high-luminosity LHC is planned for the next decade. A wide range of magnets and new technologies are currently under development.xa0One of these systems will be a set of twin aperture beam orbit correctors positioned on the approaches to the ATLAS and CMS experiments. This twin aperture magnet system comprising 16 magnets, approximately 2 m long, with large 105-mm clear aperture coils. Each aperture will independently deliver 5-T⋅m integral field, between apertures the field vectors are rotated by 90° from each other, and individually powered. This paper presents the sequence of component developments to produce a cost-effective canted cosine theta model magnet. We describe the challenges encountered during the manufacture of the coil formers with their helical canted coil winding process which places a number of insulated wires into the 2-mm-wide 5-mm-deep slot. We describe the: pressurized impregnation process, multiple jointing to connect inner and outer sets of wires within the confines of the coil assembly, and magnet assembly into support structure and yoke. Finally, we present the quench performance and initial test results of this novel coil configuration.