Attosecond pulses from X-ray free-electron lasers: status and outlook

Free-electron Lasers provide coherent radiation with a tunable central wavelength. The driving mechanism is the self-interaction of a relativistic electron beam with its own radiation field, coupled by oscillating electron orbit in the periodic magnetic field of an undulator. One main activity in FEL development is to reduce the pulse duration below a femtosecond for resolving the fastest processes in biology, chemistry and material science. This presentation gives an overview over the current status of attosecond pulses at FEL facilities and possible strategies to further reduce the pulse duration or to increase the pulse energy.