Dresden 2014 – scientific programme

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BE: Beschleunigerphysik

BE 12: Free-Electron Lasers

BE 12.1: Group Report

Thursday, April 3, 2014, 09:30–10:00, MOL 213

FLASH1 Seeding Plans — •Christoph Lechner — University of Hamburg, Hamburg, Germany

Many free-electron lasers (FELs) producing light in the UV and extreme ultraviolet (XUV) wavelength ranges start up from noise and operate in the self-amplified spontaneous emission (SASE) mode. Therefore they have typically poor longitudinal coherence. It has recently been demonstrated that when starting with an external laser beam (the so-called 'seed'), it is possible to generate photon pulses with greatly improved longitudinal coherence and higher shot-to-shot stability of the pulse spectra and energy.

For the investigation of FEL seeding, an experiment was built at the FLASH FEL user facility in Hamburg. This beamline can be used with seeds generated by high-harmonic generation (HHG), as originally planned, but also to test more sophisticated concepts. The results from these tests of high-gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) will be considered in the design process of the seeding option at the currently being constructed FEL beamline FLASH2. The baseline design of this upgrade foresees delivery of seeded radiation down to 20nm.

In this contribution, we present the FLASH1 seeding beamline including the diagnostics needed to establish six-dimensional overlap of electron bunches and seed pulses and give an overview of the FLASH1 seeding plans.