An Option to Generate Seeded FEL Radiation for FLASH1

V Grattoni,S Khan,W Hillert,J Rossbach,R W Assmann,I Hartl,C Lechner,B Manschwetus,J Bödewadt,M M Kazemi,T Plath,V Miltchev

doi:10.1088/1742-6596/1067/3/032013

Abstract

The FLASH free-electron laser (FEL) at DESY is currently operated in self-amplified spontaneous emission (SASE) mode in both beamlines FLASH1 and FLASH2. Seeding offers unique properties for the FEL pulse, such as full coherence, spectral and temporal stability. In this contribution, possible ways to carry the seeded FEL radiation to the user hall are presented with analytical considerations and simulations. For this, components of the sFLASH seeding experiment are used.

Highlights

FLASH is the soft X-ray free-electron laser (FEL) user facility operated at DESY in Hamburg [1, 2]
The sFLASH beamline has been operated in the high-gain harmonic generation scheme (HGHG) [6], which provides seeded FEL radiation at the 7th and 8th harmonics of the seed
The photon pulses produced by the sFLASH experiment are extracted from the electron beamline in an extraction chicane placed in front of the FLASH1 main undulator

Summary

INTRODUCTION

FLASH is the soft X-ray free-electron laser (FEL) user facility operated at DESY in Hamburg [1, 2]. The main advantages of a seeded FEL are the high spectral and power stability and the longitudinal coherence These improved properties arise from starting up the FEL process from the microbunching developed from the interaction with a coherent seed pulse. Installed upstream of the main undulator of FLASH1, the sFLASH experiment is dedicated to studies of FEL seeding [5]. During dedicated sFLASH beamtime, only one electron bunch per RF pulse is generated by the photo-injector, resulting in a repetition rate of 10 Hz. So far the sFLASH beamline has been operated in the high-gain harmonic generation scheme (HGHG) [6], which provides seeded FEL radiation at the 7th and 8th harmonics of the seed. The scheme uses the second modulator of the sFLASH section, where the electron bunch is energy modulated by interacting with the seed laser pulse. The FLASH1 undulator has a fixed gap, so one has to tune very carefully the energy of the electron beam in order to satisfy the FEL resonance condition at the desired wavelength, as detailed

Achievable energy modulation

Possible achievable harmonics

Estimation of the FEL performance

WORKING POINT SIMULATION

CONCLUSION

Radiator end