Parameter estimation and tuning of a multivariable RF controller with FPGA technique for the Free Electron Laser FLASH

The operation of a free electron laser in the X-ray wavelength range is the goal of the international XFEL project. The project critically depends on the linear accelerator component, where radio frequency fields have to be controlled with a very high amplitude and phase precision and under various sources of disturbances. This paper shows for the first time closed loop results of dynamic fixed order H_infin controllers implemented in a FPGA based control system on the FLASH facility at DESY.