Vorträge und Posterpräsentationen (ohne Tagungsband-Eintrag):
H. Fillunger, R. Maix, A. Danninger:
"Axial Compression Test on ITER-TFMC Conductors at Room Temperature";
Poster: SOFT 2008,
The Nb3Sn-superconductor used for the ITER TF Model Coil consists of a cable built up by 720 superconducting and 360 copper strands, surrounded by a stainless steel jacket. This conductor was wound into a stainless steel mould and heat treated in it. Due to the transformation of niobium and tin to The Nb3Sn, the conductor elongated after cool down to room temperature by 0,048 %. If the cable and the jacket were free, the smaller thermal expansion coefficient of The Nb3Sn, starting at 650 °C, would result in a bigger length of the cable than the jacket at room temperature. However, since the cable is embedded in the jacket, it is forced to have the same length.
The jacket and the cable can be considered as a double spring system, in which the elongation of the jacket must be counter-balanced by the compression of the cable. In order to describe this system, the elastic modulus of the cable must be knwon. We received from CEA Cadarache pieces from 3 different ITER TF Model Coil conductors: (i) a dummy conductor made of copper strands, (ii) the superconductor un-reacted and (iii) the superconductor reacted. Compression tests inside the jacket were performedand the elastic moduls deduced.
We find that the modulus is fairly independent of the modules of the consituents of the cable and is about a factor of 10 lower than that of the single strand. Therefore, the mechanical compression of the cable must be about 7 times higher than the measured elongation of the jacket, which is considerably more than the usually set strain limit for reacted The Nb3Sn conductors.
Erstellt aus der Publikationsdatenbank der Technischen Universität Wien.