Operation of the variable polarization undulator on the third harmonic of a SASE FEL

Le résumé fourni par la source

FLASH is a XUV and soft X-ray free-electron laser and operates as a user facility since 2005. It comprises asuperconducting LINAC with a beam energy of up to 1.35 GeV which serves two FEL beamlines in parallel:FLASH1 and FLASH2. The FLASH2 main undulator beamline generates SASE radiation up to a photon energyof 390 eV in the fundamental. Additionally, an APPLE-III type undulator has been installed downstream ofthe FLASH2 SASE undulator section to generate soft X-ray radiation with tunable polarization at the thirdharmonic of the FLASH2 main undulator wavelength. Using this so-called afterburner, photons with up to860 eV have been demonstrated with selectable polarization. We describe the suppression of the strong thirdharmonic background radiation generated by the FLASH2 main undulator, which is linearly polarized and thusdisturbs the desired polarization state.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.