Abstract The Free electron LASer at Hamburg (FLASH) is a linear accelerator of 330 m
length. It provides laser pulses with pulse duration between 10 and hundreds of fs in the soft
X-ray wavelength range below 5 nm produced in SASE process from electron bunches with
an energy up to 1.2 GeV. FLASH works in pulsed mode with a repetition rate of 10 Hz where
up to 800 bunches at a bunch spacing of 1 μs are accelerated in one macro-pulse. The
electron beam time structure is well suited for fast intra-train feedbacks using beam based …

… LLRF Systems upgrade during FLASH shutdown allowed implementation of the beam
based feedback • All modules controller by the same hardware board SIMCON-DSP • Unified
firmware and software … Intra-pulse LLRF feedback Intra-train beam based feedback …