Prof. Rene Flukiger from the CERN in Geneva, Switzerland visited our institute and gave lectures to the researchers and students on Nov. 28th, 2014. Prof. Yanwei Ma, the director of the Superconducting & New Energy Materials Department, IEECAS presided over the lectures.
In the lecture entitled with “Irradiation effects in Nb3Sn, in view of quadrupole magnets for LHC Upgrade”, Prof. R. Flukiger introduced the radiation load of the Nb3Sn quadrupoles in LHC upgrade and the effects in Nb3Sn wires due to high energy irradiation, including the change in superconducting transition temperature Tc, the variation of critical current density Jc and the small variation of upper critical field Bc2. Then he discussed the effects of high energy neutron and proton irradiation on Jc of Nb3Sn wires. For the proton irradiation, effects from two different regions: steady loss region and Bragg peak region should both be taken into account. The total irradiation effects during the operation of LHC upgrade are estimated to be 2-3 times higher than for the neutron damage alone. Though these will lead to a sizeable enhancement of Jc, the residual resistivity of the Nb3Sn wires will be increased, and thus the thermal stability of the wires will degrade. Finally, Prof. R. Flukiger introduced a recently achieved breakthrough in the pining enhancement of Nb3Sn wires. Using new procedure involving the oxidation of Zr, smaller grains can be obtained, leading to a better flux pinning and an improved Jc which is 3 times higher than before. After the lectures, Prof. R. Flukiger kindly answered some questions from the audience.
Prof. Rene Flukiger, born 1940 in Switzerland, received his Diploma in Physics at the Swiss Federal Institute of Technology (ETHZ). After accomplishing his PhD he passed two years at MIT in Cambridge (USA) and 10 years at the Forschungszentrum in Karlsruhe, where he was responsible for the development of high field superconductors for fusion magnets, he was at the University of Geneva, where he performs teaching and research on Applied Superconductivity. Now he is working in the CERN for the research of the superconducting wires used in LHC. His research interests are centered on new methods for the industrial production of superconducting wires with high critical current densities under the influence of mechanical stresses at magnetic fields up to 21 T. He is author or coauthor of more than 500 refereed articles.
