REBCO Performance at High Field With Low Incident Angle and Preliminary Tests for a 10-T Insert

New improvements in high-temperature superconductors (HTS) are encouraging for large-scale applications, particularly for high-field magnets. In this context, the "NOUGAT" project aims at designing and building a 10-T HTS insert operating inside a 20-T resistive magnet. The insert is foreseen as a stack of double pancakes wound with REBCO tapes. The combination of current and magnetic field generate large mechanical stresses. Moreover, as the conductor has strong anisotropic properties, its performances are affected by transverse magnetic fields. Therefore, they have to be studied under high magnetic field at a small disorientation, close to the longitudinal axis of the coil. The objective is to evaluate its limiting critical current. This paper reports critical current measurements on a 4-mm REBCO tape provided by SuperOx. They were performed on the tape full width under a high magnetic field of up to 23 T at 4.2 K at the Laboratoire National des Champs Magnetiques Intenses (LNCMI) at various field angles. The limiting critical current is found to be about 350 A, which represents a current margin of 57% on a basic model. Then, a preliminary test of a prototype double-pancake coil is reportedly tested at up to 16 T.