Quench testing of HTS sub-elements for 13 kA and 600 A leads designed to the specifications for the CERN Large Hadron Collider project

Ability to safely withstand and survive self quench conditions is an important consideration in the design and utilisation of HTS current leads. The provision of a non superconducting shunt path allows current to be diverted in the event of a transition to the normal state. This shunt should allow very rapid transfer of current out of the HTS material and be able to safely support the full load current for the time required to detect the fault and reduce the current to zero. However, the shunt should also be designed to minimise the increased heat load which will result from it's addition to the lead. Test of leads based on melt cast BSCCO 2212 utilising a fully integrated silver gold alloy sheath are described. The HTS sub-elements form part of a full 13 kA lead, designed to the specifications of CERN for the LHC project. The sub-elements proved able to fully comply with and exceed the quench performance required by CERN. The HTS module was quenched at the full design current and continued to maintain this current for a further minute in the absence of any coolant without any damage being incurred or degradation of subsequent performance. Results were in full agreement with calculated quench performance. Work continues on similar modules for a 600 A lead.