Development and Test Results of a Full-Size Joint Sample for the CFETR Central Solenoid Model Coil

Abstract

The central solenoid model coil (CSMC) project was launched in the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). In order to develop and verify the key techniques and manufacturing process of the full-size central solenoid (CS) coil for the China Fusion Engineering Testing Reactor (CFETR). The CFETR CSMC is designed to be a superconducting magnet of 12 T maximum magnetic field when the running current is 47.65 kA, which consists of two Nb3Sn windings in the internal high field and three Niobium-Titanium (NbTi) windings in the external low field. All the windings of the CSMC are a kind of pancake coil continuously wound one-in-hand by cable-in-conduit conductor (CICC), which are electrically connected in series by ohmic joints. To minimize the heat load of the joints to the cryogenic system, the design resistance of the joint is below 5 $\text{n}\Omega $ in operating conditions. The design of the joint is based on the concept of lap joint. A NbTi-NbTi full-size joint sample has been manufactured and tested. In this article, the design and manufacturing processes of the joint sample are described in detail, and the test results show dc resistance below 5 $\text{n}\Omega $ criterion.