Different focusing solutions for the TTF-FEL undulator

(WE-3-40)

B. Faatz  

Hamburger Synchrotronstrahlungslabor HASYLAB At Deutsches Elektronen-Synchrotron DESY Notkestr. 85, 22607 Hamburg, Germany

While aiming at shorter wavelengths, the SASE-FEL undulators become longer. Therefore, maintaining the small electron beam sizes required, the question of what kind of focusing structures should be used for optimum performance becomes of increasing interest.

Present SASE FEL undulators that have been developed and proposed for future FELS both include integrated focusing (TTF-FEL), seperate function quadrupoles combined with the natural undulator focusing (LEUTL) and triplet or FODO structures.

In this contribution, the consequence of the different undulators designs in terms of alignment (tolerances) and flexibility will be discussed.