FEL2019 - List of Authors (Pfeiffer, S.)

Paper	Title	Page
WEB04	Few-Femtosecond Facility-Wide Synchronization of the European XFEL	318
	S. Schulz, M.K. Czwalinna, M. Felber, M. Fenner, C. Gerth, T. Kozak, T. Lamb, B. Lautenschlager, F. Ludwig, U. Mavrič, J. Müller, S. Pfeiffer, H. Schlarb, Ch. Schmidt, C. Sydlo, M. Titberidze, F. Zummack DESY, Hamburg, Germany
	The first facility-wide evaluation of the optical synchronization system at the European XFEL resulted in excellent arrival time stability of the electron bunches at the end of the 2 km long linac, being measured with two individual adjacent femtosecond-resolution bunch arrival time monitors. While each of the monitors is independently linked by a stabilized optical fiber to a master laser oscillator, with one being installed in the injector area and one in the experimental hall, these two reference lasers are tightly synchronized through another few-km long fiber link. Thus, not only the accelerator performance is being benchmarked, but equally the optical synchronization infrastructure itself. Stability on this level can only be achieved by locking the RF for cavity field control to the optical reference and requires an unprecedented synchronization of the master laser oscillator to the main RF oscillator, enabled by a novel RF/optical phase detector. Finally, with the seeders of the experiment’s optical lasers synchronized to the master laser oscillator, first experiments at two independent scientific instruments proved an X-ray/optical timing jitter of few tens of femtoseconds.
	Slides WEB04 [22.142 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEB04
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP011	Longitudinal Intra-Train Beam-Based Feedback at FLASH	346
	S. Pfeiffer, Ł. Butkowski, M.K. Czwalinna, B. Dursun, C. Gerth, B. Lautenschlager, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany
	The longitudinal intra-train beam-based feedback has been recommissioned after major upgrades on the synchronization system of the FLASH facility. Those upgrades include: new bunch arrival time monitors (BAMs), the optical synchronization system accommodating the latest European XFEL design based on PM fibers, and installation of a small broadband normal conducting RF cavity. The cavity is located prior to the first bunch compressor at FLASH and allows energy modulation bunch-by-bunch (1 us spacing) on the per mille range. Through the energy dependent path length of the succeeding magnetic chicane the cavity is used for ultimate bunch arrival time corrections. Recently the RF cavity operated 1 kW pulsed solid-state amplifier was successfully commissioned. First tests have been carried out incorporating the fast cavity as actuator together with SRF stations for larger corrections in our intra-train beam-based feedback pushing now arrival time stabilities towards 5 fs (rms). The latest results and observed residual instabilities are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP011
About •	paper received ※ 20 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)

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

Paper

Title

Page

Few-Femtosecond Facility-Wide Synchronization of the European XFEL

318

S. Schulz, M.K. Czwalinna, M. Felber, M. Fenner, C. Gerth, T. Kozak, T. Lamb, B. Lautenschlager, F. Ludwig, U. Mavrič, J. Müller, S. Pfeiffer, H. Schlarb, Ch. Schmidt, C. Sydlo, M. Titberidze, F. Zummack
DESY, Hamburg, Germany

The first facility-wide evaluation of the optical synchronization system at the European XFEL resulted in excellent arrival time stability of the electron bunches at the end of the 2 km long linac, being measured with two individual adjacent femtosecond-resolution bunch arrival time monitors. While each of the monitors is independently linked by a stabilized optical fiber to a master laser oscillator, with one being installed in the injector area and one in the experimental hall, these two reference lasers are tightly synchronized through another few-km long fiber link. Thus, not only the accelerator performance is being benchmarked, but equally the optical synchronization infrastructure itself. Stability on this level can only be achieved by locking the RF for cavity field control to the optical reference and requires an unprecedented synchronization of the master laser oscillator to the main RF oscillator, enabled by a novel RF/optical phase detector. Finally, with the seeders of the experiment’s optical lasers synchronized to the master laser oscillator, first experiments at two independent scientific instruments proved an X-ray/optical timing jitter of few tens of femtoseconds.

Slides WEB04 [22.142 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEB04

About •

paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

Export •

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

WEP011

Longitudinal Intra-Train Beam-Based Feedback at FLASH

346

S. Pfeiffer, Ł. Butkowski, M.K. Czwalinna, B. Dursun, C. Gerth, B. Lautenschlager, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany

The longitudinal intra-train beam-based feedback has been recommissioned after major upgrades on the synchronization system of the FLASH facility. Those upgrades include: new bunch arrival time monitors (BAMs), the optical synchronization system accommodating the latest European XFEL design based on PM fibers, and installation of a small broadband normal conducting RF cavity. The cavity is located prior to the first bunch compressor at FLASH and allows energy modulation bunch-by-bunch (1 us spacing) on the per mille range. Through the energy dependent path length of the succeeding magnetic chicane the cavity is used for ultimate bunch arrival time corrections. Recently the RF cavity operated 1 kW pulsed solid-state amplifier was successfully commissioned. First tests have been carried out incorporating the fast cavity as actuator together with SRF stations for larger corrections in our intra-train beam-based feedback pushing now arrival time stabilities towards 5 fs (rms). The latest results and observed residual instabilities are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP011

About •

paper received ※ 20 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)

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

Export •

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