Electrical Quality Assurance for the NbTi Coils of the HL-LHC High Order Corrector Magnets

The INFN-LASA laboratory (Milano, Italy) is involved in the High-Luminosity LHC program for the design, construction, and test of 54 superconducting high-order corrector magnets. One of the challenging project stages was the transition from the construction of laboratory prototypes to the series production, awarded to industries, with the demanding requirement of maintaining high-quality production standards. Common and custom quality assurance (QA) methods were adopted for the analysis of the electrical characteristics of the coils. This paper discusses in detail the principle of the methods, their expected sensitivity, and the final observed effectiveness on the 510 produced coils. In some cases, the methods led to early defect detection thus avoiding possible severe damages during the final cold test that have already occurred for a prototype magnet not subject to the QA procedures described in this paper.