Publications in Scientific Journals:

P. Ebermann, J. Bernardi, J. Fleiter, F. Lackner, F. Meuter, M. Pieler, C. Scheuerlein, D. Schoerling, F. Wolf, A. Ballarino, L. Bottura, D. Tommasini, F. Savary, M. Eisterer:
"Irreversible degradation of Nb3Sn Rutherford cables due to transverse compressive stress at room temperature";
Superconductor Science and Technology, 31 (2018), 065009 - 065018.

English abstract:
In the framework of the Future Circular Collider design study for a 100 TeV circular collider,
16 T superconducting bending magnets based on Nb3Sn technology are being developed. A prestress
on the conductor during magnet assembly at room temperature (RT) is needed to
counteract the Lorentz forces during operation. The superconducting properties of the brittle
Nb3Sn superconductor are strain sensitive and excessive pre-stress leads to an irreversible
degradation of the superconductor. In order to determine the level of acceptable pre-stress during
the magnet assembly process, reacted and impregnated Nb3Sn cables were exposed to increasing
transverse compressive stress up to a maximum stress level of 200 MPa at RT. After each stress
cycle, the critical current of the cable specimens were characterized at 4.3 K in the FRESCA
cable test station. No significant critical current degradation was observed up to 150 MPa,
followed by degradation less than 4% after a nominal stress of 175 MPa. A dramatic permanent
critical current degradation occurred after applying a nominal stress of 200 MPa. A
comprehensive post analysis consisting of non-destructive micro-tomography followed by
microscopic characterization of metallographic cable cross sections was carried out after the
critical current test to reveal cracks in the Nb3Sn sub-elements of the loaded specimen.

critical current, irreversible degradation, transverse compressive stress, Nb3Sn, Rutherford cable, metallographic investigation of Nb3Sn composite superconductors

"Official" electronic version of the publication (accessed through its Digital Object Identifier - DOI)

Created from the Publication Database of the Vienna University of Technology.