Results of magnet tests as a basis for the design of ITER magnets

Abstract

To ensure the availability of the ITER magnets an extensive development programme has been executed to demonstrate that the technology is available on industrial scale. This programme included two major projects, firstly the development and testing of a central solenoid model coil (CSMC) with additional testing of high field inserts and secondly the development and testing of a toroidal field model coil (TFMC), both supported by investigations on conductors, structural material and critical components. The model coils have been successfully developed, fabricated and tested in dedicated test facilities at JAERI/Naka (CSMC) and Forschungszentrum Karlsruhe (TFMC), respectively. The tests confirmed that the design criteria are met by the model coils and the ITER coils can be built on this basis. Of course, the tests showed also in which areas improvements should be implemented. One concerns the Nb 3Sn conductor. To guarantee the defined margin of the current sharing temperature, advanced conductor strands with higher critical current density than those used in the model coils have to be used and are available now. The codes for mechanical behaviour, ac loss predictions and thermohydraulic behaviour gave rather good agreement with the measurements, but can still be improved. Quality assurance issues concern high voltage properties and leak tightness.