FEL2019 - List of Authors (Rossbach, J.)

Paper	Title	Page
TUP009	Integration of an XFELO at the European XFEL Facility	62
	P. Rauer, I. Bahns, W. Hillert, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany W. Decking DESY, Hamburg, Germany H. Sinn EuXFEL, Schenefeld, Germany
	Funding: Work supported by BMBF (FKZ 05K16GU4) An X-ray free-electron laser oscillator (XFELO) is a fourth generation X-ray source promising radiation with full three dimensional coherence, nearly constant pulse to pulse stability and more than an order of magnitude higher peak brilliance compared to SASE FELs. Proposed by Kim et al. in 2008 [1] an XFELO follows the concept of circulating the light in an optical cavity - as known from FEL oscillators in longer wavelength regimes - but uses Bragg reflecting crystals instead of classical mirrors. With the new European X-ray Free-Electron Laser (XFEL) facility recently gone into operation, the realization of an XFELO with radiation in the Angstrom regime seems feasible. Though, the high thermal load of the radiation on the cavity crystals, the high sensibility of the Bragg-reflection on reflection angle and crystal temperature as well as the very demanding tolerances of the at least 60 m long optical resonator path pose challenges which need to be considered. In this work these problems shall be summarized and results regarding the possible integration of an XFELO at the European XFEL facility will be presented. [1] K.-J. Kim, Y. Shvyd’ko and S. Reiche, Phys. Rev. Lett. 100 (2008), 244802.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP009
About •	paper received ※ 20 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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TUP076	Seeding R&D at sFLASH	230
	C. Lechner, S. Ackermann, R.W. Aßmann, B. Faatz, V. Grattoni, I. Hartl, S.D. Hartwell, R. Ivanov, T. Laarmann, T. Lang, M.M. Mohammad Kazemi, G. Paraskaki, A. Przystawik, J. Zheng DESY, Hamburg, Germany A. Azima, H. Biss, M. Drescher, W. Hillert, V. Miltchev, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany S. Khan DELTA, Dortmund, Germany
	Funding: Work supported by Federal Ministry of Education and Research of Germany under contract No. 05K13GU4, 05K13PE3, and 05K16PEA. Free-electron lasers (FELs) based on the self-amplified spontaneous emission (SASE) principle generate photon pulses with typically poor longitudinal coherence. FEL seeding techniques greatly improve longitudinal coherence by initiating FEL amplification in a controlled way using coherent light pulses. The sFLASH experiment installed at the FEL user facility FLASH at DESY in Hamburg is dedicated to the study of external seeding techniques. In this paper, the layout of the sFLASH seeding experiment is presented and an overview of recent developments is given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP076
About •	paper received ※ 30 September 2019 paper accepted ※ 17 October 2019 issue date ※ 05 November 2019
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THP041	Interaction of Powerful Electro-Magnetic Fields With Bragg Reflectors	673
	I. Bahns, W. Hillert, P. Rauer, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany H. Sinn EuXFEL, Schenefeld, Germany
	Funding: supported by BMBF FKZ 05K16GU4 The interaction of an X-ray free electron laser (XFEL) with a Bragg Reflector can cause a change of the lattice constant, which has a direct influence on the stability of the reflection conditions [1] and can also excite modes of vibration [2]. The dynamical thermoelastic effects of the photon-matter-interaction are simulated with a finite-element-method (FEM) using the assumptions of continuums mechanics. To compare the simulation results with measured signals, a Michelson interferometer with ultrafast photodiodes (risetime <175ps, bandwith >2GHz) has been built up. To test the experimental setup in an in-house environment a pulsed UV laser is used to introduce a temporal displacement field in a silicon crystal created by about 0.26µJ of absorbed energy. The measured signal is in agreement with the FEM simulation and has shown that if averaging over thousands of pulses is applied a resolution <0.5pm is feasible. This makes this experimental setup useful to investigate the X-ray-matter-interaction of Bragg reflectors at modern X-ray facilities. [1] S. Stoupin et al., Physical Review B 86.5 (2012): 054301. [2] B. Yang, S. Wang and J. Wu, J. Synchrotron Rad. (2018) 25, 166-176.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP041
About •	paper received ※ 23 August 2019 paper accepted ※ 31 October 2019 issue date ※ 05 November 2019
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Paper

Title

Page

Integration of an XFELO at the European XFEL Facility

62

P. Rauer, I. Bahns, W. Hillert, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
W. Decking
DESY, Hamburg, Germany
H. Sinn
EuXFEL, Schenefeld, Germany

Funding: Work supported by BMBF (FKZ 05K16GU4)
An X-ray free-electron laser oscillator (XFELO) is a fourth generation X-ray source promising radiation with full three dimensional coherence, nearly constant pulse to pulse stability and more than an order of magnitude higher peak brilliance compared to SASE FELs. Proposed by Kim et al. in 2008 [1] an XFELO follows the concept of circulating the light in an optical cavity - as known from FEL oscillators in longer wavelength regimes - but uses Bragg reflecting crystals instead of classical mirrors. With the new European X-ray Free-Electron Laser (XFEL) facility recently gone into operation, the realization of an XFELO with radiation in the Angstrom regime seems feasible. Though, the high thermal load of the radiation on the cavity crystals, the high sensibility of the Bragg-reflection on reflection angle and crystal temperature as well as the very demanding tolerances of the at least 60 m long optical resonator path pose challenges which need to be considered. In this work these problems shall be summarized and results regarding the possible integration of an XFELO at the European XFEL facility will be presented.
[1] K.-J. Kim, Y. Shvyd’ko and S. Reiche, Phys. Rev. Lett. 100 (2008), 244802.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP009

About •

paper received ※ 20 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)

TUP076

Seeding R&D at sFLASH

230

C. Lechner, S. Ackermann, R.W. Aßmann, B. Faatz, V. Grattoni, I. Hartl, S.D. Hartwell, R. Ivanov, T. Laarmann, T. Lang, M.M. Mohammad Kazemi, G. Paraskaki, A. Przystawik, J. Zheng
DESY, Hamburg, Germany
A. Azima, H. Biss, M. Drescher, W. Hillert, V. Miltchev, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Khan
DELTA, Dortmund, Germany

Funding: Work supported by Federal Ministry of Education and Research of Germany under contract No. 05K13GU4, 05K13PE3, and 05K16PEA.
Free-electron lasers (FELs) based on the self-amplified spontaneous emission (SASE) principle generate photon pulses with typically poor longitudinal coherence. FEL seeding techniques greatly improve longitudinal coherence by initiating FEL amplification in a controlled way using coherent light pulses. The sFLASH experiment installed at the FEL user facility FLASH at DESY in Hamburg is dedicated to the study of external seeding techniques. In this paper, the layout of the sFLASH seeding experiment is presented and an overview of recent developments is given.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP076

About •

paper received ※ 30 September 2019 paper accepted ※ 17 October 2019 issue date ※ 05 November 2019

Export •

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

THP041

Interaction of Powerful Electro-Magnetic Fields With Bragg Reflectors

673

I. Bahns, W. Hillert, P. Rauer, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
H. Sinn
EuXFEL, Schenefeld, Germany

Funding: supported by BMBF FKZ 05K16GU4
The interaction of an X-ray free electron laser (XFEL) with a Bragg Reflector can cause a change of the lattice constant, which has a direct influence on the stability of the reflection conditions [1] and can also excite modes of vibration [2]. The dynamical thermoelastic effects of the photon-matter-interaction are simulated with a finite-element-method (FEM) using the assumptions of continuums mechanics. To compare the simulation results with measured signals, a Michelson interferometer with ultrafast photodiodes (risetime <175ps, bandwith >2GHz) has been built up. To test the experimental setup in an in-house environment a pulsed UV laser is used to introduce a temporal displacement field in a silicon crystal created by about 0.26µJ of absorbed energy. The measured signal is in agreement with the FEM simulation and has shown that if averaging over thousands of pulses is applied a resolution <0.5pm is feasible. This makes this experimental setup useful to investigate the X-ray-matter-interaction of Bragg reflectors at modern X-ray facilities.
[1] S. Stoupin et al., Physical Review B 86.5 (2012): 054301.
[2] B. Yang, S. Wang and J. Wu, J. Synchrotron Rad. (2018) 25, 166-176.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP041

About •

paper received ※ 23 August 2019 paper accepted ※ 31 October 2019 issue date ※ 05 November 2019

Export •

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