| Paper |
Title |
Page |
| MOPPH052 |
Output Performance of the STARS HGHG Demonstrator at BESSY
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130 |
| |
- K. Goldammer, A. Meseck, B. C. Kuske
BESSY GmbH, Berlin
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BESSY is planning to construct a free-electron laser facility (STARS) to demonstrate cascaded high-gain harmonic generation (HGHG) FELs. A 325MeV superconducting linear accelerator will drive two HGHG-stages, where the second stage is seeded by the radiation from the first stage. Such a cascading of the HGHG scheme, originally pioneered by L. H. Yu, allows a reduction of the STARS output wavelength down to the few 10nm range. This paper describes the expected performance of the facility, the achievable wavelength range, the harmonic content of the radiation, the potential of super-radiant pulses and first considerations about the stability of the source.
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| MOPPH054 |
Small-Aperture Vacuum-Chamber Design for STARS
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134 |
| |
- J. Bahrdt, V. Duerr, M. Scheer, G. Wuestefeld, A. Meseck
BESSY GmbH, Berlin
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To demonstrate and investigate the cascaded HGHG-scheme proposed for the BESSY Soft X-ray FEL, BESSY plans to build a test-facility called STARS consisting of two HGHG stages. The radiator in the second stage is planned as an APPLE III device which provides the highest field for a circular beam pipe. The minimum Gap of 7 mm translates into a 5 mm inner diameter of the vacuum chamber. An analysis of the impact of the wakefields and the expected vacuum profile is thus required. Results of this analysis an vacuum measurements are presented.
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| TUBAU03 |
STARS – an FEL to Demonstrate Cascaded HGHG
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220 |
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- M. Abo-Bakr, W. Anders, J. Bahrdt, R. Follath, K. Goldammer, S. C. Hessler, K. Holldack, T. Kamps, B. C. Kuske, A. Meseck, T. Quast, J. Knobloch
BESSY GmbH, Berlin
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BESSY plans to build the BESSY Soft X-ray FEL facility, a second generation FEL for the VUV and soft x-ray range. The TDR was evaluated by the German Science Council and recommended for funding subject to the condition that cascaded high-gain harmonic generation (HGHG) be demonstrated beforehand. To this end, BESSY is proposing the demonstration facility STARS for a two-stage HGHG FEL. For efficient lasing from 40 nm to 70 nm, a 325 MeV driver linac is required. It consists of a normal-conducting gun, superconducting TESLA-type modules modified for CW operation and a bunch compressor. The two-stage HGHG cascade employs variable gap undulators, with the final amplifier being an APPLE-III device for full polarization control. A beamline with user experiment completes STARS, which is planned to remain operational even after the BESSY FEL comes online. This paper summarizes the layout of STARS, the main parameters and the expected performance.
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| WEPPH039 |
The Optical Replica Synthesizer in FLASH
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438 |
| |
- G. Angelova, V. G. Ziemann
UU/ISV, Uppsala
- J. Boedewadt, S. Khan, A. Winter
Uni HH, Hamburg
- A. Meseck
BESSY GmbH, Berlin
- E. Saldin, H. Schlarb, B. Schmidt, E. Schneidmiller, M. V. Yurkov
DESY, Hamburg
- P. M. Salen, P. van der Meulen
FYSIKUM, AlbaNova, Stockholm University, Stockholm
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During the shutdown in spring 2007 the optical replica synthesizer, a novel device to diagnose ultra-short electron bunches, is assembled in the FLASH accelerator. We report on the status of the construction work with emphasis on the two electro-magnetic undulators needed for micro-bunching and replica-pulse generation.
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