CLIQ. A new quench protection technology for superconducting magnets

CLIQ, the Coupling-Loss Induced Quench system, is a new method for protecting superconducting magnets after a sudden transition to the normal state. It offers significant advantages over the conventional technology due to its effective mechanism for heating the superconductor relying on coupling loss and its robust electrical design, which makes it more reliable and less interfering with the coil winding process. The analysis of the electro-magnetic and thermal transients during and after a CLIQ discharge allows identifying the system parameters that affect the system performance and defining guidelines for implementing this technology on coils of various characteristics. Most existing superconducting magnets can be protected by CLIQ as convincingly shown by test results performed on magnets of different sizes, superconductor types, geometries, cables and strand parameters. Experimental results are successfully reproduced by means of a novel technique for modeling non-linear dynamic effects in superconducting magnets. The design of future magnets can be adapted for improving the performance of a CLIQ-based protection system in terms of lower hot-spot temperature, safer electrical design, as well as reduced size and cost. The impact of the proposed measures, including modifications to the composition of the superconductor and addition of multiple CLIQ terminals, are analyzed and discussed. CLIQ’s fast and relatively homogeneous transfer of the coil to the normal state can enable safe magnet operation at energy densities presently incompatible with the performance of other protection systems. CLIQ technology has rapidly reached maturity and is ready for implementation on present and future high field superconducting magnets.