Studies on the LHC superconducting circuits and routine qualification of their functionalities

The Large Hadron Collider (LHC) is systematically undergoing periods of maintenance stop (either 4-5 days stops or longer Christmas breaks), after which some or all superconducting circuits have to be re-commissioned to check the correct functionality of all powering and protection systems. Detailed procedures have been developed during the past few years and they have been optimized to increase powering tests efficiency, thus reducing beam downtime. The approach to the routine qualification of the LHC powering systems is described in this paper. During the technical stops in 2011 various studies on the superconducting circuits were performed, to assess the quality of the superconducting splices of individually powered magnets and to study the quench propagation in the main magnet bus-bars. The methodology of these tests and some results are presented.