LLRF commissioning and operation at the European XFEL

概要

The European X-ray Free-Electron Laser (XFEL) at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany is a user facility providing ultrashort hard and soft X-ray flashes with a high brilliance. All LLRF stations of the injector, covering the normal conducting RF gun, A1 (8 1.3 GHz superconducting cavities (SCs)) and AH1 (8 3.9 GHz SCs), were successfully commissioned by the end of 2015. The injector was operated with beam transmission to the injector dump since then. After the conclusion of the construction work in the XFEL accelerator tunnel (XTL),the commissioning of 22 LLRF stations (A2 to A23) started with the beginning of 2017. Every station consists of a semi-distributed LLRF system controlling 32 1.3 GHz SCs. Stable operation with beam transport to the main dump (TLD) as well as through undulator sections SA1 and SA3 to the beam dump T4D was achieved. SASE light was produced in SA1 and delivered to the first users in September 2017. The current state of the LLRF systems, the LLRF commissioning planning and execution, the energy reach and the measures of its improvement as well as the operation performances reached are presented.