Events

REBCO HTS superconducting materials make it possible to consider coils with very high energy densities, because they combine high critical current densities under strong magnetic field and a very high mechanical strength. However, the implementation of these materials is remains difficult, as they present performance inhomogeneities at the microscopic scale that have a potentially destructive impact at the device scale. In this PhD, credible solutions for insulated high energy density REBCO magnets are proposed. This work was conducted in the framework of the BOSSE project, which aims at the realization of a 12 T / 1 MJ REBCO magnet used as SMES.

   
Reliable protection of insulated REBCO coils against thermal runaway can be achieved by early detection of local dissipative conditions. However, the transient voltages observed during the current variations makes the detection challenging. This transient electromagnetic behavior of REBCO insulated coils was studied experimentally and numerically on a heavily instrumented test coil, enabling a detailed interpretation of the measured voltages.
This new understanding was applied to the BOSSE project, starting with the tests of the prototype Double Pancake (DP) in self and background magnetic field, to safely reach the critical current and validate the design of the solenoid. Each of the 21 series DPs of the BOSSE solenoid are then tested in liquid helium up to their rated current for quality control. Finally, 2 preliminary assemblies of 3 and 5 DPs were tested using the same early detection and protection approach, validating the protection strategies of the full-scale device.

   
Based on the understanding gained from these new developments, a new high-performance REBCO coil design with conductive cooling capability is proposed.