FEL2019 - List of Authors (Mehrjoo, M.)

Paper	Title	Page
TUP077	Study of a Seeded Oscillator-Amplifier FEL	234
	G. Paraskaki, S. Ackermann, B. Faatz, V. Grattoni, C. Lechner, M. Mehrjoo DESY, Hamburg, Germany G. Geloni, S. Serkez, T. Tanikawa EuXFEL, Schenefeld, Germany W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	In recent years, there is interest of the Free-Electron Laser (FEL) community in external-seeding techniques such as the Echo-Enabled Harmonic Generation (EEHG) and the High-Gain Harmonic Generation (HGHG). With these techniques, pulses of an improved temporal coherence are generated, but at the same time, they are limited by the repetition rates that seed lasers can currently offer with the required pulse energies. A big challenge is to combine the advantages of seeding schemes with high repetition rates. For this purpose, we study a combination of an oscillator-amplifier. The modulator in the oscillator is used at a long wavelength to modulate the electron beam and an amplifier is operated to extract the FEL radiation of the desired harmonic. This way we can use a seed laser of 10 Hz in a burst mode and a resonator to feedback the radiation at repetition rates of superconducting accelerators instead of using an external seed at these high-repetition rates. In this contribution, we present simulation results of a seeded oscillator-amplifier FEL in an HGHG scheme.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP077
About •	paper received ※ 19 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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WEP072	Expected Radiation Properties of the Harmonic Afterburner at FLASH2	492
	M. Mehrjoo, B. Faatz, G. Paraskaki, M. Tischer, P. Vagin DESY, Hamburg, Germany
	We discuss the afterburner option to upgrade the FLASH2 undulator line, at the FLASH facility in the Hamburg area, for delivering short wavelengths down to approximately 1.5 nm with variable polarization. This relatively straightforward upgrade enables us the study of the scientific cases in L- absorption edges of rare earth metals. The proposed afterburner setting with an energy upgrade to 1.35 GeV would potentially cover many of the community’s requests for the short wavelengths radiation and circular polarization. We also study the influence of reverse tapering on the radiation output. This contribution presents a series of simulations for the afterburner scheme and some of the technical choices made for implementation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP072
About •	paper received ※ 19 August 2019 paper accepted ※ 28 October 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Study of a Seeded Oscillator-Amplifier FEL

234

G. Paraskaki, S. Ackermann, B. Faatz, V. Grattoni, C. Lechner, M. Mehrjoo
DESY, Hamburg, Germany
G. Geloni, S. Serkez, T. Tanikawa
EuXFEL, Schenefeld, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

In recent years, there is interest of the Free-Electron Laser (FEL) community in external-seeding techniques such as the Echo-Enabled Harmonic Generation (EEHG) and the High-Gain Harmonic Generation (HGHG). With these techniques, pulses of an improved temporal coherence are generated, but at the same time, they are limited by the repetition rates that seed lasers can currently offer with the required pulse energies. A big challenge is to combine the advantages of seeding schemes with high repetition rates. For this purpose, we study a combination of an oscillator-amplifier. The modulator in the oscillator is used at a long wavelength to modulate the electron beam and an amplifier is operated to extract the FEL radiation of the desired harmonic. This way we can use a seed laser of 10 Hz in a burst mode and a resonator to feedback the radiation at repetition rates of superconducting accelerators instead of using an external seed at these high-repetition rates. In this contribution, we present simulation results of a seeded oscillator-amplifier FEL in an HGHG scheme.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP077

About •

paper received ※ 19 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP072

Expected Radiation Properties of the Harmonic Afterburner at FLASH2

492

M. Mehrjoo, B. Faatz, G. Paraskaki, M. Tischer, P. Vagin
DESY, Hamburg, Germany

We discuss the afterburner option to upgrade the FLASH2 undulator line, at the FLASH facility in the Hamburg area, for delivering short wavelengths down to approximately 1.5 nm with variable polarization. This relatively straightforward upgrade enables us the study of the scientific cases in L- absorption edges of rare earth metals. The proposed afterburner setting with an energy upgrade to 1.35 GeV would potentially cover many of the community’s requests for the short wavelengths radiation and circular polarization. We also study the influence of reverse tapering on the radiation output. This contribution presents a series of simulations for the afterburner scheme and some of the technical choices made for implementation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP072

About •

paper received ※ 19 August 2019 paper accepted ※ 28 October 2019 issue date ※ 05 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)