TUA —  SASE FELs   (25-Aug-15   08:30—10:00)
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TUA01
 Generating Femtosecond to Sub-Femtosecond X-Ray Pulses at Free-Electron Lasers  
 
  • Y. Ding
    SLAC, Menlo Park, California, USA
  
  Generation of high power, femtosecond to sub-femtosecond X-ray pulses is attracting much attention within the X-ray free-electron laser (FEL) user community. At the existing FEL facilities, such as the Linac Coherent Light Source at SLAC, low-charge operation mode and emittance-spoiling foil scheme have been developed to deliver sub-10 fs X-rays to user experiments. We recently performed extensive measurements on these two modes using the X-band transverse deflector diagnostic at LCLS, demonstrating a flexible pulse duration control with direct measurements. To achieve sub-fs X-ray pulses, a simple nonlinear compression mode has been recently developed with pulse duration about 200 as [1]. Experimental study of this sub-fs mode will be pursued in this year. We report the recent experimental studies for generating femtosecond to sub-fs x-ray pulses.
[1] S. Huang, Y. Ding, Z. Huang, and J. Qiang, Phys. Rev. ST Accel. Beams 17, 120703 (2014) 		 
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TUA02 Suppression of FEL Lasing by a Seeded Microbunching Instability 289
 
  • C. Lechner, A. Azima, M. Drescher, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Rönsch-Schulenburg, J. Roßbach
    Uni HH, Hamburg, Germany
  • S. Ackermann, J. Bödewadt, G. Brenner, M. Dohlus, N. Ekanayake, T. Golz, T. Laarmann, T. Limberg, E. Schneidmiller, N. Stojanovic, M.V. Yurkov
    DESY, Hamburg, Germany
  • K.E. Hacker, S. Khan, R. Molo
    DELTA, Dortmund, Germany
  
  Funding: Supported by Federal Ministry of Education and Research of Germany under contract No. 05K10PE1, 05K10PE3, 05K13GU4, and 05K13PE3 and the German Research Foundation programme graduate school GRK1355.
Collective effects and instabilities due to longitudinal space charge and coherent synchrotron radiation can degrade the quality of the ultra-relativistic, high-brightness electron bunches driving free-electron lasers (FELs). In this contribution, we demonstrate suppression of FEL lasing induced by a laser-triggered microbunching instability at the free-electron laser FLASH. The interaction between the electron bunches and the 800-nm laser pulses takes place in an undulator upstream of the FEL undulators. A significant decrease of XUV photon pulse energies has been observed in coincidence with the laser-electron overlap in the modulator. We discuss the underlying mechanisms based on longitudinal space charge amplification (LSCA) [E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST Accel. Beams 13, 110701 (2010)] and present measurements. 		 
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TUA03 Multi-beamline Operation Test at SACLA 293
 
  • T. Hara, T. Inagaki, R. Kinjo, C. Kondo, Y. Otake, H. Takebe, H. Tanaka, K. Togawa
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • K. Fukami
    JASRI/SPring-8, Hyogo-ken, Japan
  
  A new undulator beamline (BL2) was installed in September 2014 at SACLA. Following the installation of this second beamline, a DC switching magnet was replaced by a kicker magnet and a DC septum magnet for bunch-to-bunch multi-beamline operation. The commissioning of the new beamline and bunch-to-bunch operation was started early this year. Since SACLA has been operated with much higher peak currents around 10 kA compared to its original design value of 3 kA, the CSR effect in the beam transport line to BL2, where the electron beam is deflected twice by 3 degree, turns out to be non-negligible. BL2 is currently operated with reduced peak currents and the photon pulse energies of 100-150 μJ are obtained with increased undulator K-values around 2.6-2.85. Although the photon pulse energies of BL2 are still smaller than those of the existing beamline (BL3), the expected stability of the electron beam orbit after the bunch-to-bunch BL switching was achieved and simultaneous lasing at the two beamlines was demonstrated with 8 GeV electron beams. We will report the status and operational issues related to the multi-beamline operation at SACLA.  
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TUA04 First Simultaneous Operation of Two Sase Beamlines in FLASH 297
 
  • M. Scholz, B. Faatz, S. Schreiber, J. Zemella
    DESY, Hamburg, Germany
  
  FLASH2, the second undulator beamline of the FLASH FEL user facility at DESY (Hamburg, Germany) is under commissioning. Its first lasing was achieved in August 2014. FLASH is the first soft X-ray FEL operating two undulator beamlines simultaneously. Both undulator beamlines are driven by a common linear superconducting accelerator with a beam energy of up to 1.25 GeV. Fast kickers and a septum are installed to distribute one part of the electron bunch train to FLASH1 and the other part to FLASH2 with full repetition rate. The commissioning of FLASH2 takes place primarily in parallel to FLASH1 user operation. Various beam optics measurements has been carried out in order to ensure the required electron beam quality for efficient SASE generation. This paper reports the status of the FLASH2 commissioning.  
slides icon Slides TUA04 [9.655 MB]  
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