A Laser Pulse Controller for the Injector Laser at FLASH and European XFEL

FLASH is a multi-beamline free-electron laser user facility which provides femtosecond long high brilliant photon pulses in the extreme-UV and soft-X ray wavelength range. One pulsed superconducting LINAC accelerates electron bunches for three undulator beamlines. Within each RF-pulse trains of hundreds of electron bunches are produced in a photo-cathode RF gun, accelerated in the LINAC and distributed by fast kickers into the undulator beamlines. In order to fulfill the parameter ranges of the multiple user experiments each bunch train can be tuned individually in bunch number from 0-600, spacing from 1µs-100µs and intensity from 0.1nC-1nC. To make this possible, three injector laser systems are used and this allows FLASH to vary independently the laser settings for the different bunch trains. A laser controller has been newly developed to make the multi-users operation mode possible. A Field Programmable Gate Array (FPGA) controls the time structure of the laser pulses and it provides the interface for the timing and the machine protection system. The controller has been implemented using the MicroTCA.4 technology. Since the end of 2015 the same system controls the injector LASER at the European XFEL facility