Nondestructive Testing and Quality Control of the LHC Main Interconnection Splices

Abstract

The Large Hadron Collider (LHC) main interconnection splices consist of Rutherford-type cable splice and busbar stabilizer splices. Busbar stabilizer splices have been consolidated during the first long LHC shutdown by soldering additional Cu shunts. In view of the large number of quality controls (QCs) that were integrated in the splice consolidation process, efficient and unambiguous QC procedures needed to be developed. Directcurrent electrical resistance measurements have been selected for the control of the busbar splices and the individual shunts. About 400 000 resistance measurements performed at room temperature before and after each consolidation step have been analyzed. The resistance of the consolidated splices is comparable with the resistance of continuous busbars without splice. Resistance changes during the consolidation process correspond to those calculated from the changes in Cu cross-sectional area.

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

“…This was the outcome of the visual control and electrical resistance measurements from ElQC team performed on all main splices throughout LS1. The two main reasons for this was a large interconnection resistance > 5 μΩ [11] and geometrical imperfections of the interconnections. This would have prevented the shunt application due to required copper surface preparation by unacceptable reduction of the busbar copper thickness [12].…”

“…6(a) represents a shunted 13 kA splice of a dipole busbar circuit. The subsequent working step during the LS1 was given by the electrical quality control [11] and the installation of the new insulation system. A finalized installation of the new insulation system is shown in Fig.…”

“…The highest excess resistance at room temperature is now 1 μΩ compared to 107 μΩ before. The additional Cu cross-section provided by the shunt is now providing lower resistance than a continuous busbar without splice [11]. …”

Electromechanical behaviour of REBCO tape lap splices under transverse compressive loading

“…As an example, the about 8000 superconducting magnets of the LHC [1] are interconnected with several ten thousand splices [2,3,4]. Splices are also required in hybrid magnets or in graded magnets [5] and in the magnets of fusion energy reactors [6].…”

“…The electrical interconnection of superconductors enables their application in devices like electromagnets. As an example, the about 8000 superconducting magnets of the LHC [1] are interconnected with several tens of thousands of splices [2][3][4]. Splices are also required in hybrid magnets or in graded magnets [5] and in the magnets of fusion energy reactors [6].…”