Splice Resistance Measurements in the LHC Main Superconducting Magnet Circuits by the New Quench Protection System

The interconnections between the LHC main magnets are made of soldered joints (splices) of two superconducting cables stabilized by a copper bus-bar. After the 2008 LHC incident, caused by a defective interconnection, a new layer of high resolution magnet circuit quench protection (nQPS) has been developed and integrated with the existing systems. It allowed mapping of the resistances of all superconducting splices during the 2009 commissioning campaign. Since April 2010, when the LHC was successfully restarted at 3.5 TeV, every bus bar interconnection is constantly monitored by the nQPS electronics. The acquired data are saved to the LHC Logging Database. The paper will briefly describe the data analysis method and will present the results from the two years of resistance measurements. Although no splice was found with resistance higher than 3.3 n and no significant degradation in time was observed so far, the monitoring of splices will stay active till the end of LHC 4 TeV run. The detected outliers will be repaired during the Splice Consolidation Campaign in 2013-2014