Development and test of XFEL modulator prototypes

The European XFEL, an X-ray free electron laser, is planned as an European project with a strong connection to the DESY research center in Hamburg. Construction started in summer 2007 and commissioning will begin at the end of 2013. The LINAC of the XFEL incorporates 27 RF stations, which supply the RF power required by the superconducting cavities. In order to generate the RF pulses (1.3GHz, 10MW) HV pulse modulators are required to operate the klystrons. Each modulator has to supply 12kV pulses at 1.8kA for 1.7ms pulse duration. A 1:12 pulse transformer converts these pulses to a level of 120kV at 140A required at the cathode of the klystrons. Although extensive experience exists from the test facilities FLASH (DESY, Hamburg site) and PITZ (DESY, Zeuthen site) a dedicated modulator test stand has been setup to test and investigate new modulator prototypes developed by different companies. The test stand setup is similar to the setup of the future XFEL RF-stations.