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Abstract:
The Variable pulse length Storage Ring (BESSY VSR) upgrade to BESSY II at Helmholtz-Zentrum Berlin (HZB) requires an upgrade on the RF systems in the form of highvoltage longitudinally focusing super conducting RF cavities of 1.5 GHz and 1.75 GHz. Coaxial RF power couplers capable of handling 13 kW peak power at standing wave operation, are required to provide an average power of 1.5 kW for both the 1.5 GHz and 1.75 GHz cavities. The coupler is intended to provide variable coupling with a range of Qext from 6106 to 6107 providing flexibility to adjust to operating conditions of BESSY VSR. Here we present the RF design of the high-power 1.5 GHz coaxial coupler for BESSY VSR.