Stainless steel sheathed forced internally cooled Nb3Sn superconductor and its coil test

Forced cooled Nb3Sn superconducting coil with the stainless steel sheathed conductor has been manufactured and tested in a High Field Test Facility (HFTF). Some properties of the sheath material and the conductor with stainless steel sheath have been investigated. A 316L stainless steel sheathed conductor (the outer dimension of 13 × 23 mm²) was fabricated, and one coil was completed by the wind and react method using this conductor. The coil was connected with 8 pancake coils made of copper sheathed conductor. The forced cooled magnet of 9 double pancake coils was tested under 5.9 T of the back up field in HFTF and generated 8.8 T under 7.6 kA of transport current. Experimental results show that the Nb3Sn strand in the copper sheathed conductor near the connector was degraded due to handling through reconnecting the conductor for several times.