J. Mazet

Principles developed for the construction of the high performance, low-cost superconducting LHC corrector magnets

The Large Hadron Collider (LHC) needs more than 6000 superconducting corrector magnets. These must be sufficiently powerful, have enough margin, be compact and of low cost. The development of the 11 types of magnets was spread over several years and included the magnetic and mechanical design as well as prototype building and testing. It gradually led to the systematic application of a number of interesting construction principles that allow to realize the above mentioned goals. The paper describes the techniques developed and presently used in practically all the LHC corrector magnets ranging from dipoles to dodecapoles.

Further development of the sextupole and decapole spool corrector magnets for the LHC

In the Large Hadron Collider (LHC) the main dipoles will be equipped with sextupole (MCS) and decapole (MCD) spool correctors to meet the very high demands of field quality required for the satisfactory operation of the machine. Each decapole corrector will in addition have an octupole insert (MCO) and the assembly of the two is designated MCDO. These correctors are needed in relatively large quantities, i.e. 2464 MCS Sextupoles and 1232 MCDO Decapole-Octupole assemblies. Half the number of the required spool correctors will be made in India through a collaboration between CERN and CAT (Centre for Advanced Technology, Indore, India), the other half will be built by European industry. The paper describes final choices concerning design, materials, production techniques, and testing so as to assure economic magnet manufacture but while maintaining a homogenous magnetic quality that results in a robust product.

Status of the production of the LHC superconducting corrector magnets

The Large Hadron Collider (LHC) will be equipped with a large number (6400) of superconducting corrector magnets. These magnets are powerful, with typical peak fields of 3-4 T on the coils, but at the same time compact and of low cost. There are many types: sextupoles, octupoles and decapoles to correct the main dipole field, dipoles, quadrupoles, sextupoles and octupoles to condition the proton beams and several nested correctors from dipole to dodecapole in the inner triplets. The sizes vary from 6 kg, 110 mm long, nested decapole-octupole spool pieces to 1800 kg, 1.4 m long, trim quadrupoles. The fabrication of the 11 different types of magnets is assured by 10 contracts placed at 6 firms, two of which are in India. A number of magnets are now in series production, others in their pre-series production. The paper describes the present state of the fabrication and the testing of these magnets.

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.

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.

Design of Nb3Sn Wiggler Magnets for the Compact Linear Collider and Manufacturing of a Five-Coil Prototype

To achieve the luminosity requirements of the Compact Linear Collider (CLIC) at the collision point, damping rings (DRs) equipped with superconducting wiggler magnets should be used to produce ultralow emittance with high bunch charge. Although Nb-Ti wigglers meet the specifications for CLIC DRs, the more challenging Nb3Sn technology could be used to increase the magnetic flux density amplitude in the gap and reduce the total length of wigglers in the DRs. To test the Nb3Sn technology, a small wiggler prototype is under design and will be built and tested at CERN. Magnetic calculations concerning the selection of the main wigglers parameters are presented in this paper, which include the optimization of the main coil dimensions and the period length, in order to fulfill the normalized emittance and intrabeam scattering effect constraints, while decreasing the amount of wigglers in the DRs. Another advantage of using Nb3Sn, instead of Nb-Ti, as superconducting material is the possibility of increasing the working margin. Several scenarios well suited for CLIC damping wigglers, in which the working point is less than 80% of the magnets current limit, are addressed in this work. In addition, the description of the manufacturing process and the current status of the Nb3Sn prototype fabrication are presented.

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.