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For the XFEL, housed in a single tunnel, most of the modulators will be placed in a central modulator building outside of the tunnel. The pulse transformers and the klystrons will be positioned inside the tunnel near the superconducting linac. Therefore the energy has to be transported via pulse cables. These cables have lengths between 350m and 1.7 km. The power is up to 16.8 MW per pulse with a repetition rate of 10 Hz. In order to keep the rise time short and match the klystron impedance four 25Ohm cables will be put in parallel. A tri-axial design was chosen to prevent magnetic field outside of the cables in order not to disturb electronics or electron beam. A prototype of the cable was produced in industry and delivered to DESY. A set of four 1.5km long parallel cables is in test at present at one of the modulators of the TTF/VUV-FEL at DESY. The cable design criteria and test results are presented in this paper.
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