IBIC2013 - List of Keywords (free-electron-laser)

Paper	Title	Other Keywords	Page
MOPC33	Status of the Fiber Link Stabilization Units at FLASH	laser, electron, FEL, polarization	139
	F. Zummack, M.K. Czwalinna, M. Felber, T. Lamb, H. Schlarb, S. Schulz, C. Sydlo DESY, Hamburg, Germany S. Jabłoński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	State-of-the-art X-ray photon science with modern free-electron lasers (FEL) like FLASH and the upcoming European X-ray Free-Electron Laser Facility (XFEL) requires timing with femtosecond accuracy. For this purpose a sophisticated pulsed optical synchronization system distributes precise timing via length-stabilized fiber links throughout the entire FEL. Stations to be synchronized comprise bunch arrival time monitors, RF stations and optical cross-correlators for external lasers. The different requirements of all those stations have to be met by one optical link-stabilization-unit (LSU) design, compensating drifts and jitter in the distribution system down to a fs-level. Five years of LSU operation at FLASH have led to numerous enhancements resulting in an elaborate system. This paper presents these enhancements, their impact on synchronization performance and the latest state of the LSUs.

WEPC41	Comparative Analysis of Different Electro-Optical Intensity Modulator Candidates for the New 40 GHz Bunch Arrival Time Monitor System for FLASH and European XFEL	laser, pick-up, electron, insertion	782
	A. Kuhl, J. Rönsch-Schulenburg, J. Roßbach Uni HH, Hamburg, Germany M.K. Czwalinna, C. Gerth, H. Schlarb, C. Sydlo DESY, Hamburg, Germany S. Schnepp ETH Zurich, Institute of Electromagnetic Fields (IFH), Zurich, Switzerland T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: The work is supported by Federal Ministry of Education and Research of Germany (BMBF) within FSP 301 under the contract numbers 05K10GU2 and 05K10RDA. The currently installed Bunch Arrival time Monitors (BAMs) at the Free electron LASer in Hamburg (FLASH) achieved a time resolution of less than 10 fs for bunch charges higher than 500 pC. In order to achieve single spike FEL pulses at FLASH, electron bunch charges down to 20 pC are of interest. With these BAMs the required time resolution is not reachable for bunch charges below 500 pC. Therefore new pickups with a bandwidth of up to 40 GHz are designed and manufactured. The signal evaluation takes place with a time-stabilized reference laser pulse train which is modulated with an Electro-Optical intensity Modulator (EOM). The new BAM system also requires new EOMs for the electro-optical frontend. The available selection of commercial EOM candidates for the new frontend is very limited. In this paper we present a comparison between different EOM candidates for the new electro optical frontend. A. Angelovski et al. Proceedings Phys. Rev ST AB, DOI:10.1103/PhysRevSTAB.15.112803
	Poster WEPC41 [0.619 MB]

WEPF06	A Fast Switching Mirror Unit at FLASH	vacuum, laser, site, DESY	818
	F. Perlick, J.D. Good, N. Leuschner, A.S. Ontoso, M. Sachwitz, L.V. Vu DESY Zeuthen, Zeuthen, Germany H. Schulte-Schrepping DESY, Hamburg, Germany
	The Free Electron Laser (FLASH) at DESY Hamburg is a linac providing unique experimental opportunities to investigate the atomic structure and the properties of materials, nanoparticles, viruses and cells. At the experimental hall, the incoming FEL beam can be deflected towards five test sites by silicon mirrors mounted into vacuum vessels, of which one is operated in permanent switching mode, allowing the simultaneous use of the light at two different test sites. So far, the entire vacuum vessel with the mirror inside is moved into the beam by a linear motor. This results in high translatory inertia and, to compensate the vessel motion, requires vacuum bellows, which have a limited lifetime especially at higher switching frequencies. Therefore, in the recent design the mirror is shifted by piezo motors operated inside the vessel under ultra-high vacuum conditions. However, temperature measurements revealed that during continuous operation the motor reaches up to 90°C only when exposed to air, necessitating long breaks to allow it to cool. Therefore suitable cooling methods are being investigated to guarantee continuous operation of the motor under ultra-high vacuum conditions.
	Poster WEPF06 [2.431 MB]

WEPF21	Scanning Wire Beam Position Monitor for Alignment of a High Brightness Inverse-Compton X-ray Source	laser, electron, scattering, alignment	856
	M.R. Hadmack, E.B. Szarmes University of Hawaii, Honolulu, HI, USA
	Funding: US Department of Homeland Security DNDO ARI program GRANT NO. 2010-DN-077-ARI045-02 The Free-Electron Laser Laboratory at the University of Hawaii has constructed and tested a scanning wire beam position monitor to aid the alignment and optimization of a high spectral brightness inverse-Compton scattering X-ray source. X-rays are produced by colliding the 40 MeV electron beam from a pulsed S-band LINAC with infrared laser pulses from a mode-locked free-electron laser driven by the same electron beam. The electron and laser beams are focused to 60 micron diameters at the interaction point to achieve high scattering efficiency. This wire-scanner allows for high resolution measurements of the size and position of both the laser and electron beams at the interaction point to verify spatial coincidence. Time resolved measurements of secondary emission current allow us to monitor the transverse spatial evolution of the e-beam throughout the duration of a 4 microsecond macropulse while the laser is simultaneously profiled by pyrometer measurement of the occulted infrared beam. Using this apparatus we have demonstrated that the electron and laser beams can be co-aligned with a precision better than 10 microns as required to maximize X-ray yield.
	Poster WEPF21 [14.675 MB]

Paper

Title

Other Keywords

Page

MOPC33

Status of the Fiber Link Stabilization Units at FLASH

laser, electron, FEL, polarization

139

F. Zummack, M.K. Czwalinna, M. Felber, T. Lamb, H. Schlarb, S. Schulz, C. Sydlo
DESY, Hamburg, Germany
S. Jabłoński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

State-of-the-art X-ray photon science with modern free-electron lasers (FEL) like FLASH and the upcoming European X-ray Free-Electron Laser Facility (XFEL) requires timing with femtosecond accuracy. For this purpose a sophisticated pulsed optical synchronization system distributes precise timing via length-stabilized fiber links throughout the entire FEL. Stations to be synchronized comprise bunch arrival time monitors, RF stations and optical cross-correlators for external lasers. The different requirements of all those stations have to be met by one optical link-stabilization-unit (LSU) design, compensating drifts and jitter in the distribution system down to a fs-level. Five years of LSU operation at FLASH have led to numerous enhancements resulting in an elaborate system. This paper presents these enhancements, their impact on synchronization performance and the latest state of the LSUs.

WEPC41

Comparative Analysis of Different Electro-Optical Intensity Modulator Candidates for the New 40 GHz Bunch Arrival Time Monitor System for FLASH and European XFEL

laser, pick-up, electron, insertion

782

A. Kuhl, J. Rönsch-Schulenburg, J. Roßbach
Uni HH, Hamburg, Germany
M.K. Czwalinna, C. Gerth, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
S. Schnepp
ETH Zurich, Institute of Electromagnetic Fields (IFH), Zurich, Switzerland
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: The work is supported by Federal Ministry of Education and Research of Germany (BMBF) within FSP 301 under the contract numbers 05K10GU2 and 05K10RDA.
The currently installed Bunch Arrival time Monitors (BAMs) at the Free electron LASer in Hamburg (FLASH) achieved a time resolution of less than 10 fs for bunch charges higher than 500 pC. In order to achieve single spike FEL pulses at FLASH, electron bunch charges down to 20 pC are of interest. With these BAMs the required time resolution is not reachable for bunch charges below 500 pC. Therefore new pickups with a bandwidth of up to 40 GHz are designed and manufactured*. The signal evaluation takes place with a time-stabilized reference laser pulse train which is modulated with an Electro-Optical intensity Modulator (EOM). The new BAM system also requires new EOMs for the electro-optical frontend. The available selection of commercial EOM candidates for the new frontend is very limited. In this paper we present a comparison between different EOM candidates for the new electro optical frontend.
* A. Angelovski et al. Proceedings Phys. Rev ST AB, DOI:10.1103/PhysRevSTAB.15.112803

Poster WEPC41 [0.619 MB]

WEPF06

A Fast Switching Mirror Unit at FLASH

vacuum, laser, site, DESY

818

F. Perlick, J.D. Good, N. Leuschner, A.S. Ontoso, M. Sachwitz, L.V. Vu
DESY Zeuthen, Zeuthen, Germany
H. Schulte-Schrepping
DESY, Hamburg, Germany

The Free Electron Laser (FLASH) at DESY Hamburg is a linac providing unique experimental opportunities to investigate the atomic structure and the properties of materials, nanoparticles, viruses and cells. At the experimental hall, the incoming FEL beam can be deflected towards five test sites by silicon mirrors mounted into vacuum vessels, of which one is operated in permanent switching mode, allowing the simultaneous use of the light at two different test sites. So far, the entire vacuum vessel with the mirror inside is moved into the beam by a linear motor. This results in high translatory inertia and, to compensate the vessel motion, requires vacuum bellows, which have a limited lifetime especially at higher switching frequencies. Therefore, in the recent design the mirror is shifted by piezo motors operated inside the vessel under ultra-high vacuum conditions. However, temperature measurements revealed that during continuous operation the motor reaches up to 90°C only when exposed to air, necessitating long breaks to allow it to cool. Therefore suitable cooling methods are being investigated to guarantee continuous operation of the motor under ultra-high vacuum conditions.

Poster WEPF06 [2.431 MB]

WEPF21

Scanning Wire Beam Position Monitor for Alignment of a High Brightness Inverse-Compton X-ray Source

laser, electron, scattering, alignment

856

M.R. Hadmack, E.B. Szarmes
University of Hawaii, Honolulu, HI, USA

Funding: US Department of Homeland Security DNDO ARI program GRANT NO. 2010-DN-077-ARI045-02
The Free-Electron Laser Laboratory at the University of Hawaii has constructed and tested a scanning wire beam position monitor to aid the alignment and optimization of a high spectral brightness inverse-Compton scattering X-ray source. X-rays are produced by colliding the 40 MeV electron beam from a pulsed S-band LINAC with infrared laser pulses from a mode-locked free-electron laser driven by the same electron beam. The electron and laser beams are focused to 60 micron diameters at the interaction point to achieve high scattering efficiency. This wire-scanner allows for high resolution measurements of the size and position of both the laser and electron beams at the interaction point to verify spatial coincidence. Time resolved measurements of secondary emission current allow us to monitor the transverse spatial evolution of the e-beam throughout the duration of a 4 microsecond macropulse while the laser is simultaneously profiled by pyrometer measurement of the occulted infrared beam. Using this apparatus we have demonstrated that the electron and laser beams can be co-aligned with a precision better than 10 microns as required to maximize X-ray yield.

Poster WEPF21 [14.675 MB]