FEL2014 - List of Authors (Steffen, B.)

Paper

Title

Page

Operation of FLASH with Short SASE-FEL Radiation Pulses

342

J. Rönsch-Schulenburg, E. Hass, N.M. Lockmann, T. Plath, M. Rehders, J. Roßbach
Uni HH, Hamburg, Germany
G. Brenner, S. Dziarzhytski, T. Golz, H. Schlarb, B. Schmidt, E. Schneidmiller, S. Schreiber, B. Steffen, N. Stojanovic, S. Wunderlich, M.V. Yurkov
DESY, Hamburg, Germany

Funding: The project has been supported by the Federal Ministry of Education and Research of Germany (BMBF) under contract No. 05K10GU2 and FSP301
This paper describes the experimental activity on the generation of very short FEL pulses in the soft x-ray range in the SASE-mode at the high-gain free-electron laser FLASH [1, 2]. The key element, a photo-injector laser which is able to generate laser pulses of about 2 ps FWHM has been optimized and commissioned. It allows the generation of shorter bunches with low bunch charge (of up to 200 pC) directly at the photo-cathode. Initially shorter injector laser pulses and thus shorter bunches eases the required bunch compression factor for short pulses below 10 fs duration which makes operation of the electron beam formation system to be more robust with respect to jitters and collective effects. As a result, overall stability of SASE FEL performance is improved. In the optimal case single-spike operation can be achieved. In this paper the experimental results on production of short electron bunches and the SASE performance using the new injector laser will be shown and the measured electron bunch and FEL radiation properties are discussed. In addition, optimizations of bunch diagnostics for low charge and short bunches are discussed.

Slides TUB04 [1.201 MB]

THP089

Compact Synchronization of Optical Lasers to the Accelerator RF based on MTCA.4

C. Gerth, Ł. Butkowski, M. Felber, U. Mavrič, P. Peier, H. Schlarb, B. Steffen
DESY, Hamburg, Germany
E. Janas
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
T. Kozak, P. Prędki, K.P. Przygoda
TUL-DMCS, Łódź, Poland

X-ray free-electron laser facilities utilize a variety of optical short-pulse lasers to fully exploit the femtosecond time structure of the electron bunches and photon pulses. For temporal overlap, a precision synchronization of the optical lasers to the radio-frequency (RF) system of the FEL accelerator is required. A compact scheme for laser to external RF synchronization has been developed based on a digital controller implemented in MTCA.4 technology. An RF section is employed for the generation of electrical signals from the laser pulses. Further processing of the RF signals and phase locking to the reference is realized with commercially available MTCA.4 compliant modules. In this paper, we present a performance evaluation of the newly designed RF section, which consists of three printed circuit boards, as well as results from the synchronization of an Yb-fiber (1030 nm) and Er-fiber (1550 nm) laser to an RF reference source.

Paper	Title	Page
TUB04	Operation of FLASH with Short SASE-FEL Radiation Pulses	342
	J. Rönsch-Schulenburg, E. Hass, N.M. Lockmann, T. Plath, M. Rehders, J. Roßbach Uni HH, Hamburg, Germany G. Brenner, S. Dziarzhytski, T. Golz, H. Schlarb, B. Schmidt, E. Schneidmiller, S. Schreiber, B. Steffen, N. Stojanovic, S. Wunderlich, M.V. Yurkov DESY, Hamburg, Germany
	Funding: The project has been supported by the Federal Ministry of Education and Research of Germany (BMBF) under contract No. 05K10GU2 and FSP301 This paper describes the experimental activity on the generation of very short FEL pulses in the soft x-ray range in the SASE-mode at the high-gain free-electron laser FLASH [1, 2]. The key element, a photo-injector laser which is able to generate laser pulses of about 2 ps FWHM has been optimized and commissioned. It allows the generation of shorter bunches with low bunch charge (of up to 200 pC) directly at the photo-cathode. Initially shorter injector laser pulses and thus shorter bunches eases the required bunch compression factor for short pulses below 10 fs duration which makes operation of the electron beam formation system to be more robust with respect to jitters and collective effects. As a result, overall stability of SASE FEL performance is improved. In the optimal case single-spike operation can be achieved. In this paper the experimental results on production of short electron bunches and the SASE performance using the new injector laser will be shown and the measured electron bunch and FEL radiation properties are discussed. In addition, optimizations of bunch diagnostics for low charge and short bunches are discussed.
	Slides TUB04 [1.201 MB]

THP089	Compact Synchronization of Optical Lasers to the Accelerator RF based on MTCA.4
	C. Gerth, Ł. Butkowski, M. Felber, U. Mavrič, P. Peier, H. Schlarb, B. Steffen DESY, Hamburg, Germany E. Janas Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland T. Kozak, P. Prędki, K.P. Przygoda TUL-DMCS, Łódź, Poland
	X-ray free-electron laser facilities utilize a variety of optical short-pulse lasers to fully exploit the femtosecond time structure of the electron bunches and photon pulses. For temporal overlap, a precision synchronization of the optical lasers to the radio-frequency (RF) system of the FEL accelerator is required. A compact scheme for laser to external RF synchronization has been developed based on a digital controller implemented in MTCA.4 technology. An RF section is employed for the generation of electrical signals from the laser pulses. Further processing of the RF signals and phase locking to the reference is realized with commercially available MTCA.4 compliant modules. In this paper, we present a performance evaluation of the newly designed RF section, which consists of three printed circuit boards, as well as results from the synchronization of an Yb-fiber (1030 nm) and Er-fiber (1550 nm) laser to an RF reference source.