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WEOA02 |
Photocathodes at FLASH |
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- S. Schreiber, H. Hansen, S. Lederer, H.-H. Sahling
DESY, Hamburg, Germany
- P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy
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Since several years, caesium telluride photocathodes are successfully used in the photoinjector of the Free-Electron-Laser FLASH at DESY, Germany. They show a high quantum efficiency and long lifetime and produce routinely thousands of bunches per second with a single bunch charge mostly in the range of 20 pC to 3 nC. Recent studies on lifetime, quantum efficiency, darkcurrent, and operating experience is reported.
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Slides WEOA02 [3.563 MB]
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| WEOA03 |
Machine Protection for Single-Pass FELs |
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- L. Fröhlich
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
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The linacs driving modern single-pass FELs carry electron beams of unprecedented brightness. Their average power ranges from few watts to hundreds of kilowatts. At the same time, these machines are equipped with unusual amounts of instrumentation that need to be protected from beam losses. The FEL process itself depends crucially on the precision of the magnetic field inside undulator structures that are prone to demagnetization under radiation exposure. This combination makes machine protection for FELs both a necessity and a challenge. The talk gives an overview of typical hazards and of machine protection strategies adopted at FELs in various laboratories.
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Slides WEOA03 [1.375 MB]
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| WEOA04 |
Time-Resolved Images of Coherent Synchrotron Radiation Effects in the LCLS First Bunch Compressor |
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- P. Emma
LBNL, Berkeley, California, USA
- C. Behrens
DESY, Hamburg, Germany
- Z. Huang, F. Zhou
SLAC, Menlo Park, California, USA
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Funding: We thank the US Department of Energy under contract number DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) is an x-ray Free-Electron Laser (FEL) facility now in operation at SLAC. One of the limiting effects on electron beam brightness is the coherent synchrotron radiation (CSR) generated in the bunch compressor chicanes, which can significantly dilute the bend-plane (horizontal) emittance. Since simple emittance measurements* do not tell the full story, we would like to see the time-dependent CSR-kicks along the length of the bunch. We present measured images and simulations of the effects of CSR seen on an intercepting beam screen just downstream of the LCLS BC1 chicane while powering a skew quadrupole magnet near the center of the chicane [ ]. The skew quadrupole maps the time coordinate of the pre-BC1 bunch onto the vertical axis of the screen, allowing the time-dependent CSR-induced horizontal effects to become clearly visible.
* K. Bane et al., Phys. Rev. ST Accel. Beams 12, 030704 (2009).
** K. Bertsche, P. Emma, O. Shevchenko, "A Simple, Low Cost Longitudinal Phase Space Diagnostic", PAC'09, Vancouver, BC, Canada, 2009.
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Slides WEOA04 [3.159 MB]
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