In the framework of the MADMAX project, a European project around dark matter research, a big dipole composed of 18 skateboard shape coils has been designed. This dipole has large aperture dimensions (diameter of 1.35 m on 1.3 m long), a magnetic field of 9 T and a gigantic stored energy of 527 MJ. Combining these characteristics is an important scientific and technological challenge. To achieve such challenges, a novel Cable-In-Conduit-Conductor (CICC) has been developed, composed of a superconducting cable inserted in a copper profile and filled with stagnant superfluid helium.
However, this novel configuration is unique and thus no study is available in the literature. To combine the scientific challenges presented above with a novel conductor, different issues must be addressed and one of the most important is the “quench issue”. Therefore, the objective of this PhD work is to experimentally study and numerically model the quench behavior in order to understand the driving phenomena of the quench propagation.
To do so, a mock-up coil called MACQU (MAdmax Coil for Quench Understanding), specially designed to reproduce the same MADMAX’s features, has been tested at CEA Saclay. A large testing temperature range (from 1.75 K to 2.01 K), with a large testing current range (from 10 kA to 17 kA) were tested. It allowed to demonstrate the safety of the detection system, and validated the conductor design for MADMAX. MACQU also allowed to study the quench propagation and shown a particular quench behavior, called the Thermal-Hydraulic-Quench-Back (THQB).
To take into account this phenomena, an analytical quench propagation speed formula has been developed and has been benchmarked with the quench-dedicated numerical tool THEA®. THEA® also allowed to observe the THQB phenomena and to identify the driving phenomena of the quench propagation of such a novel CICC.