Generation of femtosecond X-ray pulses via laser-electron beam interaction

The generation of femtosecond X-ray pulses will have important scientific a pplications by enabling the direct measurement of atomic motion and structu ral dynamics in condensed matter on the fundamental time scale of a vibrati onal period. Interaction of femtosecond laser pulses with relativistic elec tron beams is an effective approach to generating femtosecond pulses of X-r ays. In this paper we present recent results from proof-of-principle experi ments in which 300 fs pulses are generated from a synchrotron storage ring by using an ultrashort optical pulse to create femtosecond time structure o n the stored electron bunch. A previously demonstrated approach for generat ing femtosecond X-rays via Thomson scattering between terawatt laser pulses and relativistic electrons is reviewed and compared with storage-ring base d schemes.