Abstract
Autor: Baerchi
with an experiment to study directly seeded FEL operation in the XUV
regime. A laser is shot into a gas target, where it produces a beam of
the desired seeding wavelength (the seed) together with several other
higher harmonics of the fundamental laser wavelength. The electron
beam and the seeding beam are overlapped spatially and temporally in
the seeding undulators where the seed will be amplified. Furthermore,
due to the intrinsic temporal correlation between the arrival of FEL
photons and seeding photons, a laser seeded FEL offers the possibility
to drive pump-probe experiments with femtosecond synchronisation.
For the optimal FEL performance it is necessary to have good coupling
between the seed and the electrons and therefore the knowledge
on the electron optics parameters is of crucial importance. In sFLASH
these parameters are calculated by measuring the transverse electron
beam profiles using special OTR-Screens.
Tolerance studies have been performed regarding errors of the gradients
of each quadrupole in the lattice and the resolution of the used
OTR screens.
Further experiments to show the usability of this method were performed
at FLASH (DESY). The goal is to develop an easy to use tool
for emittance and Twiss function measurement and matching.
