WEOBB03
SLAC, Menlo Park, California, USA
DESY, Hamburg, Germany
We report on measurements of the longitudinal phase space profile of the bunch as it evolves along the length of the LCLS undulator. An x-band transverse deflecting cavity downstream of the undulator makes time resolved energy profile measurements with fs resolution. The electron energy loss mechanism of the FEL process is observed and allows us to reconstruct the temporal profile of the x-ray pulse on a shot by shot basis. We have been able to observe with unprecedented resolution microbunching in the beam and resonant energy loss leading to exponential gain and saturation in the FEL, as well as provide the users with the temporal profile of the x-rays on every shot.
SLAC, Menlo Park, California, USA
The beam stability of the Linac Coherent Light Source (LCLS) has seen many improvements over the years and has matured to a state where progress is slow and maintaining the best stability is becoming the main challenge. Single sources which are identified by various means contribute to only about 10 to 20% of the whole jitter power, meaning that their elimination gives only a small improvement of 5 to 10%. New sources need to be identified fast. Especially slow variations of a few seconds to minutes time scale are often hidden and partially corrected by feedback systems. A few episodes of increased jitter have shown the limitations of some of the feedback systems. Stability for all dimensions, transverse, longitudinal, and intensity are presented.