Qualification of key process for ITER correction coils

Abstract

• The winding pack from conductor was successfully winded and insulated. • The quality of the helium inlet welding could meet the requirement. • The case enclosure welding was qualified with laser welding technology. • The superconducting joint was characterized with outstanding performance. ITER correction coils system, which is composed of 18 superconducting coils, is designed to correct magnet asymmetries and reduce the magnet error caused by the manufacturing and assembly of the TOKAMAK. Depending on the function and the operating environment of the magnets system, the correction coil is mainly composed of the winding pack with insulation, Helium inlet and outlet, superconducting joint, the stainless-steel case outside the winding pack. These components would directly affect the final property of the correction coil, therefore all the key process during the coil manufacturing need to be qualified before the series production. The key qualification process includes the process of winding, welding for the helium inlet and outlet, vacuum pressure impregnation, case closure welding and the superconducting joint manufacture. This article describes each qualified process in detail, including the requirement of the qualification both for the product and the process, the mock up designed both for the sample and the prototype, and the activities for the manufacturing and test as well as the results.