Studies on a Diagnostic Pulse for FLASH

The long-term stability of the beam optics at FLASH is crucial for all connected experiments and the operation of the new second beamline FLASH2. It is therefore desirable to have a simple procedure to monitor the beam optics rou- tinely and at the same time minimally invasive. This way user operation is not disturbed. An automated procedure, which has been successfully employed at the SLAC linac is presented in the context of FLASH. The betatron oscilla- tions of selectively kicked pulses are recorded using BPMs at a fixed time interval. An online algorithm is then used to extract the betatron phase advance, as well as potential growth of the betatron oscillation amplitude and the Twiss parameters beta and alpha. Using this method, the long-term beam optics stability can be monitored in order to identify potential sources of drifts