FEL2019 - List of Authors (Winkelmann, L.)

Paper	Title	Page
WEP046	The European XFEL Photocathode Laser	423
	L. Winkelmann, A. Choudhuri, U. Grosse-Wortmann, I. Hartl, C. Li, C. Mohr, J. Müller, F. Peters, S. Pfeiffer, S.H. Salman DESY, Hamburg, Germany
	We present the Yb:fiber, Nd:YVO4 laser used to generate electrons from the RF photocathode gun at the European XFEL. The laser provides deep UV output pulses in 600 µs bursts with variable internal repetition rate (564 kHz to 4.5 MHz). Due to its robust architecture (mode-locked and synchronized fiber oscillator, Yb:fiber amplifiers and Nd:YVO4 gain blocks), the laser has operated with >99% uptime since January 2017. Using this laser, the XFEL reported energies of 17.5 GeV in July 2018, and simultaneous multi-mJ lasing in its three SASE beamlines. The laser offers two parallel outputs (1064 nm) with single pulse energies of >100 µJ and 11 ps width (FWHM). One output is converted to deep UV with efficiencies > 25%, and the second is used as a laser heater to reduce microbunching instabilities to increase SASE efficiency. Several state-of-art laser controls were implemented, including feed-forward algorithm to flatten electron charge along the bunch, active beam stabilization with < ±10 µm jitter at the photocathode, state machines for hands-off end-user operation, and temporal pulse synchronization and drift compensation to the timing jigger of the electron bunches to less than 45 fs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP046
About •	paper received ※ 23 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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WEP050	Status of Chirped Pulse Laser Shaping for the PITZ Photoinjector	437
	C. Koschitzki, Y. Chen, J.D. Good, M. Groß, M. Krasilnikov, G. Loisch, R. Niemczyk, F. Stephan DESY Zeuthen, Zeuthen, Germany E. Khazanov, S. Mironov IAP/RAS, Nizhny Novgorod, Russia T. Lang, L. Winkelmann DESY, Hamburg, Germany
	The beam emittance at FEL facilities like European XFEL and FLASH is dominated by the emittance sources in the electron injector. Shaping of the laser pulses that are employed to release electrons from the cathode of a photo injector, was shown in theory to allow improved beam emittance starting from the electron emission process. At the photo injector test facility at DESY in Zeuthen (PITZ) a laser system capable of controlling the temporal and spatial profile of laser pulses is being set up to demonstrate the predicted emittance reduction experimentally. The presentation will show its current capabilities to provide temporally and spatially shaped laser pulses from a pulse shaper operating at infrared (IR) wavelengths. Furthermore, results from a shape preserving conversion into fourth harmonic ultra-violet (UV), as needed for the photo emission process, will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP050
About •	paper received ※ 21 August 2019 paper accepted ※ 17 September 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

The European XFEL Photocathode Laser

423

L. Winkelmann, A. Choudhuri, U. Grosse-Wortmann, I. Hartl, C. Li, C. Mohr, J. Müller, F. Peters, S. Pfeiffer, S.H. Salman
DESY, Hamburg, Germany

We present the Yb:fiber, Nd:YVO4 laser used to generate electrons from the RF photocathode gun at the European XFEL. The laser provides deep UV output pulses in 600 µs bursts with variable internal repetition rate (564 kHz to 4.5 MHz). Due to its robust architecture (mode-locked and synchronized fiber oscillator, Yb:fiber amplifiers and Nd:YVO4 gain blocks), the laser has operated with >99% uptime since January 2017. Using this laser, the XFEL reported energies of 17.5 GeV in July 2018, and simultaneous multi-mJ lasing in its three SASE beamlines. The laser offers two parallel outputs (1064 nm) with single pulse energies of >100 µJ and 11 ps width (FWHM). One output is converted to deep UV with efficiencies > 25%, and the second is used as a laser heater to reduce microbunching instabilities to increase SASE efficiency. Several state-of-art laser controls were implemented, including feed-forward algorithm to flatten electron charge along the bunch, active beam stabilization with < ±10 µm jitter at the photocathode, state machines for hands-off end-user operation, and temporal pulse synchronization and drift compensation to the timing jigger of the electron bunches to less than 45 fs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP046

About •

paper received ※ 23 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)

WEP050

Status of Chirped Pulse Laser Shaping for the PITZ Photoinjector

437

C. Koschitzki, Y. Chen, J.D. Good, M. Groß, M. Krasilnikov, G. Loisch, R. Niemczyk, F. Stephan
DESY Zeuthen, Zeuthen, Germany
E. Khazanov, S. Mironov
IAP/RAS, Nizhny Novgorod, Russia
T. Lang, L. Winkelmann
DESY, Hamburg, Germany

The beam emittance at FEL facilities like European XFEL and FLASH is dominated by the emittance sources in the electron injector. Shaping of the laser pulses that are employed to release electrons from the cathode of a photo injector, was shown in theory to allow improved beam emittance starting from the electron emission process. At the photo injector test facility at DESY in Zeuthen (PITZ) a laser system capable of controlling the temporal and spatial profile of laser pulses is being set up to demonstrate the predicted emittance reduction experimentally. The presentation will show its current capabilities to provide temporally and spatially shaped laser pulses from a pulse shaper operating at infrared (IR) wavelengths. Furthermore, results from a shape preserving conversion into fourth harmonic ultra-violet (UV), as needed for the photo emission process, will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP050

About •

paper received ※ 21 August 2019 paper accepted ※ 17 September 2019 issue date ※ 05 November 2019

Export •

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