Scheme for time-resolved experiments based on the use of statistical properties of the third harmonic of the SASE FEL radiation

A closer inspection of the statistical properties of the third-harmonic radiation from the SASE FEL reveals that it is possible to select single, temporary coherent radiation spikes by using a simple intensity trigger. A carefully designed optical system for splitting, delaying, filtering, and recombining the radiation would then allow time-resolved measurements with resolution down to the coherence time of the FEL, i.e. a few femtoseconds in the case of the TTF FEL. (C) 2003 Elsevier Science B.V. All rights reserved.