We report recent results on the performance of FLASH (Free Electron Laser in Hamburg) operating at a wavelength of 13.7 nm where unprecedented peak and average powers for a coherent EUV radiation source have been measured. In the saturation regime the peak energy approached 170 µJ for individual pulses while the average energy per pulse reached 70 µJ. The pulse duration was in the region of 10 femtoseconds and peak

Two-color, single-shot time-of-flight electron spectroscopy of atomic neon was employed at the Linac Coherent Light Source (LCLS) to measure laser-assisted Auger decay in the x-ray regime. This x-ray-optical cross-correlation technique provides a straightforward, non-invasive and online means of determining the duration of femtosecond (>40 fs) x-ray pulses.In combination with a theoretical model of the process based on the softphoton approximation, we were able to obtain the LCLS pulse duration and to extract a mean value of the temporal jitter between the optical pulses from a synchronized Ti-sapphire laser and x-ray pulses from the LCLS. We find that the experimentally determined values are systematically smaller than the length of the electron bunches. Nominal electron pulse durations of 175 and 75 fs, as provided by the LCLS control system, yield x-ray pulse shapes of 120 ± 20 fs full-width at half-maximum (FWHM) and an upper limit of 40 ± 20 fs FWHM, respectively. Simulations of the free-electron laser agree well with the experimental results. Contents