Title :

Characterization of soft x-ray echo-enabled harmonic generation free-electron laser pulses in the presence of incoherent electron beam energy modulations

Author(s) :

Mirian, N.S. [Auteur]
Perosa, G. [Auteur]
Hemsing, E. [Auteur]
Allaria, E. [Auteur]
Badano, L. [Auteur]
Cinquegrana, P. [Auteur]
Danailov, M.B. [Auteur]
de Ninno, G. [Auteur]
Giannessi, L. [Auteur]
Penco, G. [Auteur]
Spampinati, S. [Auteur]
Spezzani, C. [Auteur]
Roussel, E. [Auteur]
Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 [PhLAM]
Ribic, P.R. [Auteur]
Trovo, M. [Auteur]
Veronese, M. [Auteur]
Di Mitri, S. [Auteur]

Journal title :

Phys.Rev.Accel.Beams

Pages :

080702

Publication date :

2021

HAL domain(s) :

Physique [physics]/Physique [physics]/Physique des accélérateurs [physics.acc-ph]

English abstract : [en]

Echo-enabled harmonic generation free-electron lasers (EEHG FELs) are promising candidates to produce fully coherent soft x-ray pulses by virtue of efficient high-harmonic frequency up-conversion from ultraviolet lasers. ...
Show more >Echo-enabled harmonic generation free-electron lasers (EEHG FELs) are promising candidates to produce fully coherent soft x-ray pulses by virtue of efficient high-harmonic frequency up-conversion from ultraviolet lasers. The ultimate spectral limit of EEHG, however, remains unclear, because of the broadening and distortions induced in the output spectrum by residual broadband energy modulations in the electron beam. We present a mathematical description of the impact of incoherent (broadband) energy modulations on the bunching spectrum produced by the microbunching instability through both the accelerator and the EEHG line. The model is in agreement with a systematic experimental characterization of the FERMI EEHG FEL in the photon energy range 130–210 eV. We find that amplification of electron beam energy distortions primarily in the EEHG dispersive sections explains an observed reduction of the FEL spectral brightness proportional to the EEHG harmonic number. Local maxima of the FEL spectral brightness and of the spectral stability are found for a suitable balance of the dispersive sections’ strength and the first seed laser pulse energy. Such characterization provides a benchmark for user experiments and future EEHG implementations designed to reach shorter wavelengths.Show less >

Language :

Anglais

Popular science :

Non

Collections :

• Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL