FEL2014 - List of Authors (Dziarzhytski, S.)

Paper

Title

Page

The Photon Beam Loss Monitors as a Part of Equipment Protection System at European XFEL

37

N. Gerasimova, H. Sinn
XFEL. EU, Hamburg, Germany
S. Dziarzhytski, R. Treusch
DESY, Hamburg, Germany

For the X-ray beam transport systems, the problem of potential damage to the equipment by mis-steered photon beam emerged with advent of powerful X-ray FELs. In particular high repetition rate machines as European XFEL, where not only focused beam can produce ablation, but even unfocused beam can melt the beamline components while machine operates in multibunch mode, demand for implementation of equipment protection. Here we report on development of photon beam loss monitors at European XFEL facility. The photon beam loss monitors will react on the mis-steered photon beam and interface the machine protection system. The prototype comprises the vacuum chamber with fluorescence crystals positioned outside the photon beampath. The fast sub-hundred ns fluorescence induced by mis-steered beam can be detected by photomultiplier tube allowing for intra-train reaction of machine protection system. First tests have been carried out at FLASH and shown the feasibility of detection based on PMT-detected fluorescence. In addition to efficient YAG:Ce crystal, the robust low-Z material as CVD microcrystalline diamonds has shown a potential to be used as fluorescence crystals.

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]

Paper	Title	Page
MOP010	The Photon Beam Loss Monitors as a Part of Equipment Protection System at European XFEL	37
	N. Gerasimova, H. Sinn XFEL. EU, Hamburg, Germany S. Dziarzhytski, R. Treusch DESY, Hamburg, Germany
	For the X-ray beam transport systems, the problem of potential damage to the equipment by mis-steered photon beam emerged with advent of powerful X-ray FELs. In particular high repetition rate machines as European XFEL, where not only focused beam can produce ablation, but even unfocused beam can melt the beamline components while machine operates in multibunch mode, demand for implementation of equipment protection. Here we report on development of photon beam loss monitors at European XFEL facility. The photon beam loss monitors will react on the mis-steered photon beam and interface the machine protection system. The prototype comprises the vacuum chamber with fluorescence crystals positioned outside the photon beampath. The fast sub-hundred ns fluorescence induced by mis-steered beam can be detected by photomultiplier tube allowing for intra-train reaction of machine protection system. First tests have been carried out at FLASH and shown the feasibility of detection based on PMT-detected fluorescence. In addition to efficient YAG:Ce crystal, the robust low-Z material as CVD microcrystalline diamonds has shown a potential to be used as fluorescence crystals.

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]