Consolidation of the 13-<roman>kA</roman> Superconducting Magnet Circuits of the LHC at CERN

Abstract

The first long shutdown (LS1) of the LHC machine at CERN started in February 2013. The main trigger for LS1 was the consolidation of the bus bar joints in the 13-kA superconducting magnet circuits. Before LS1, the copper continuity of these joints was not sufficiently good to ensure a safe passage of the current in case of a quench in the superconducting cable at currents larger than 7-8 kA. The consolidation mainly consists in adding shunts made of high conductivity copper across each joint connecting the bus bars of the neighboring magnets in order to ensure the copper continuity. After LS1, the LHC can then be operated up to the original nominal conditions, i.e., a collision energy of 14 TeV. There are 1695 interconnects, each containing six 13-kA joints, of which two belong to the main dipole circuit and four to the main quadrupole circuits. This paper describes the different steps of the consolidation work performed on the 10 170 magnet-to-magnet joints. The work on the splices proper has been organized in the form of a train made of six production teams, all together consisting of about 90 persons, including operators, supervision, and quality assurance. The work flow is managed with the help of a web-based tool called WISH. This paper describes as well the quality control and quality assurance methods put in place to ensure the quality of the work throughout the project, and it summarizes the benefits of the consolidation work in terms of copper continuity, operation margin, and robustness of the new insulation system. Index Terms-LHC long shutdown one, quality assurance, SMACC, superconducting splices.

LHC Upgrades in preparation of Run 3

“…LS1 was motivated by the need to consolidate the 13 kA splices between the superconducting magnets to allow the LHC to approach the design beam energy of 7 TeV in addition to the necessary regular maintenance of the equipment. The Superconducting Magnets and Circuits Consolidation (SMACC) project has principally covered the consolidation of more than ten thousands 13 kA splices but also other activities linked to the superconducting magnets such as the exchange of 18 main cryomagnets, the installation of additional safety relief devices, the repair of known helium leaks, and other consolidation activities [4]. The above modifications allowed to reach a proton beam energy of 6.5 TeV during the following Run 2 (2015-2018), after an extensive training campaign of the superconducting magnets.…”

Retraining of the 1232 Main Dipole Magnets in the LHC

“…PC=Power Converter; CL=Current Lead; Extr=Energy Extraction system. [11]. In the coming years the LHC is planned to be operated at a beam energy of 6.5 TeV, requiring a dipole magnet current of 10980 A.…”

Nondestructive Testing and Quality Control of the LHC Main Interconnection Splices

“…Each shunt acts as a redundant system, which can carry the full current during the current decay time in the circuit [6], [7]. The splice repair and consolidation procedures are reported elsewhere [8]. In this paper, we describe the splice quality controls (QCs) that have been performed by the so-called ELectrical QC, or ELQC team, and we present the main results of these controls.…”