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Kaertner, F. X.

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TUPMS041 The Wisconsin VUV/Soft X-ray Free Electron Laser Project 1278
  • J. Bisognano, R. A. Bosch, M. A. Green, H. Hoechst, K. Jacobs, K. J. Kleman, R. A. Legg, R. Reininger, R. Wehlitz
    UW-Madison/SRC, Madison, Wisconsin
  • J. Chen, W. Graves, F. X. Kaertner, J. Kim, D. E. Moncton
    MIT, Cambridge, Massachusetts
  Funding: Work supported by the University of Wisconsin - Madison. SRC is supported by the U. S. National Science Foundation under Award No. DMR-0537588.

The University of Wisconsin-Madison and its partners are developing a design for an FEL operating in the UV to soft x-ray range that will be proposed as a new multidisciplinary user facility. Key features of this facility include seeded, fully coherent output with tunable photon energy and polarization over the range 5 eV to 1240 eV, and simultaneous, independent operation of multiple beamlines. The different beamlines will support a wide range of science from femto-chemistry requiring ultrashort pulses with kHz repetition rates to photoemission and spectroscopy requiring high average flux and narrow bandwidth at MHz rates. The facility will take advantage of the flexibility, stability, and high average pulse rates available from a CW superconducting linac driven by a photoinjector. This unique facility is expected to enable new science through ultra-high resolution in the time and frequency domains, as well as coherent imaging and nano-fabrication. This project is being developed through collaboration between the UW Synchrotron Radiation Center and MIT. We present an overview of the facility, including the motivating science, and its laser, accelerator, and experimental systems.

TUPMS042 A Superconducting Linac Driver for the Wisconsin Free Electron Laser 1281
  • J. Bisognano, R. A. Bosch, M. A. Green, K. Jacobs, K. J. Kleman, R. A. Legg
    UW-Madison/SRC, Madison, Wisconsin
  • J. Chen, W. Graves, F. X. Kaertner, J. Kim
    MIT, Cambridge, Massachusetts
  Funding: Work supported by the University of Wisconsin - Madison. SRC is supported by the U. S. National Science Foundation under Award No. DMR-0537588.

We present an initial design of the driver for the Wisconsin VUV/Soft Xray FEL facility, which will provide high intensity coherent photons from 5 eV to 1.2 keV. It uses a 2.5 GeV, L-band CW superconducting linac with a 1.7 GeV tap-off to feed the lower energy FELs. In order to support multiple high rep-rate FELs, the average design current is 1 mA. Sub-nanocoulomb bunches with normalized transverse emittances of order 1 micron are generated in a photoinjector for beamlines operating at repetition rates from kHz to MHz. Multi-stage bunch compression provides 1 kA peak current to the FELs, with low energy spread and a suitable current profile. Compressed bunch lengths of several hundred femtoseconds will allow generation of photon pulses in the range 10 to 100 fs using cascaded FELs. Consideration has been given to removing the residual energy chirp from the beam, and minimizing the effects of space charge, coherent synchrotron radiation, and microbunching instabilities. A beam switchyard using RF separators and fast kickers delivers the desired electron bunches to each of the FELs. Details of the design will be presented, including those areas requiring the most development work.

FROAC04 Sub-10 Femtosecond Stabilization of a Fiber Link Using a Balanced Optical Cross Correlator 3804
  • F. Loehl, H. Schlarb
    DESY, Hamburg
  • J. Chen, F. X. Kaertner, J. Kim, F. Wong
    MIT, Cambridge, Massachusetts
  • J. M. Mueller
    TUHH, Hamburg
  Synchronization of various components with fs stability is needed for the operation of free-electron-lasers such as FLASH or the European XFEL. One possibility to realize a high precision synchronization is to use a mode-locked Er-doped fiber laser as a master clock and to distribute ultra short laser pulses inside the machine using actively stabilized fiber links. In this paper we demonstrate the stabilization of a 300 m long fiber link with a self-aligned balanced cross-correlator using a single type II phase-matched PPKTP crystal. This approach allowed us to reduce the timing jitter added by the link to below 10 fs.  
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