Ultrashort radiation pulses at storage rings

With the advent of linac-based SASE-FELs, the investigation of ultrashort phenomena on the sub-picosecond scale is becoming a rapidly growing field of research. Synchrotron radiation sources based on storage rings offer a broad range of photon energies and higher repetition rates than linear accelerators, but have an inherently longer pulse duration of typically several ten picoseconds. However, different techniques have been developed to generate ultrashort radiation pulses ranging from the THz to the X-ray regime at storage rings. Several of these techniques will be outlined in this talk. For example in Germany, BESSY, ANKA and the MLS are regularly operated in low-alpha mode, a femto-slicing source exists at BESSY, and the CHG (coherent harmonic generation) scheme is employed by the DELTA short-pulse facility, for which EEHG (echo-enabled harmonic generation) is planned as an upgrade.