SAFETY PROTECTION OF SERIES CONNECTED HYBRID CRYOGENIC SYSTEM Free

Two Series Connected Hybrid (SCH) magnets are under construction at the National High Magnetic Field Laboratory. In the SCH system, consisting of a resistive insert and a superconducting outsert, the outsert superconducting coil is wound with Cable in Conduit Conductor (CICC) and cooled with forced‐flow supercritical helium at 4.5 K. The forced‐flow helium is supplied from a helium refrigerator. In the design of the cryogenic system for the series‐connected hybrid, the possible failure of the magnet system should be considered and the cryogenic system should be safely protected in the event of failure. In the SCH system, a protected quench of the superconducting magnet, a loss of vacuum in the cryostat and an unprotected quench were analyzed. Active venting valves, safety valves and burst disks are used for the protection of the cryogenic system and cryostat in the case of the occurrence of failure modes. The design of the safety protection system and the analysis results in the failure modes are discussed.