An iterative learning control approach combined with a multivariable RF controller for the Free Electron Laser FLASH

Controlling large scale radio frequency fields in a superconducting linear accelerator to a certain accuracy demands high requirements of the control system. The pulsed operation mode allows the application of iterative learning control algorithms beside the real time feedback controller. This paper presents design and application of an iterative learning controller which operates on an underlying control loop with a low-order H
_∞
controller. Measurement results are given from the FPGA based control system at the FLASH facility at DESY.