SIS100 By-pass line - from the sketch into the tunnel

Abstract In Darmstadt, Germany, the Facility for Antiproton and Ion Research (FAIR) is presently under construction. One of the most complex machines is the SIS100, a synchrotron with a circumference of 1100 metres. Since the accelerating structures for heavy ions are normal conducting and have to be operated at room temperature a cryogenic by-pass line is required to by-pass these warm components. The by-pass line provides continuity around the synchrotron for liquid helium and houses the superconducting bus bars for the electric current. This 300m long by-pass line system has been developed in close collaboration between GSI and the Wrocław University of Science and Technology (WUST). The design must fulfil both the mechanical requirements of the overall system in respect of interfaces to other components and the demanding requirements for the arrangement of the bus bars. The magnet system of SIS100 will be a fast-ramped from a few hundred amperes to almost 14 kA within 0.5 seconds. The bus bars must therefore be both stable against electromagnetic forces and flexible to compensate for thermal shrinkage. Following an intensiv design phase, the production responsibilities were assigned to Kriosystem. After the production of the first prototype, the complete series of 27 diverse by-pass line modules, consisting of 5 main layout, was finalised. This article summarises some of the challenges during design and production phase, tests which were successfully carried out and, last but not least, the installation in the tunnel. Furthermore, an outlook is given on the upcoming final assembly and connection to the magnets.