| Paper |
Title |
Page |
| MOPC030 |
Operation of FLASH at 6.5 nm Wavelength
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133 |
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- S. Schreiber, B. Faatz, K. Honkavaara
DESY, Hamburg
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FLASH, the Free-Electron-Laser at DESY, Germany has been upgraded in 2007. A 6th accelerating module with eight 9-cell superconducting cavities of the TESLA type has been installed. In addition, another module has been replaced and the tuners of a third module have been repaired. In September 2007, a beam energy of 1 GeV has been achieved for the first time, followed by lasing at 6.5 nm shortly after. With this remarkable achievement, the initial design goals of the FEL in terms of beam energy and wavelength have been reached.
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| WEPC118 |
Study of Controllable Polarization SASE FEL by a Crossed-planar Undulator
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2282 |
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- B. Faatz, Y. Li, J. Pflueger, E. Saldin, E. Schneidmiller, M. V. Yurkov
DESY, Hamburg
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A potential and economical access to generate arbitrary polarized XFEL is to utilize crossed-undulator scheme instead of helical undulators. In this paper, the polarization of x-ray radiation for the European XFEL is investigated. The degree of polarization and the Stokes parameters are calculated for different configurations. The shot-to-shot fluctuation of polarization and the degree of polarization distribution over the transverse plane are also studied.
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| WEPC129 |
Undulator Demagnetization due to Radiation Losses at FLASH
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2308 |
| |
- J. Skupin, B. Faatz, Y. Li, J. Pflueger, T. Vielitz
DESY, Hamburg
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The free-electron laser FLASH was set up at DESY Hamburg in 2004. It is a high-gain, single pass FEL which operates in the VUV and soft X-ray wavelength regime. To monitor the demagnetization of the undulator structures due to radiation losses a small test undulator was installed. This dosimetric undulator (DU) consists of a short piece of magnetic undulator structure with only 3 pole pairs and corresponding magnets. It is positioned in front of the first undulator module where a high dose rate is to be expected. The accumulated dose of DU and undulator system is derived by weekly measurements with thermoluminescence dosimeters (TLDs). The DU is dismounted and magnetically measured regularly. Based on these measurements a (maximal) relative demagnetization rate of about 5*10-4/kGy was derived. In view of this result magnetic measurements on one of the undulators from TTF1 (the predecessor of FLASH) were reviewed. They show a relative demagnetization rate of about 2*10-4/kGy which is lower but still in the same range as the result from FLASH. FEL simulations to analyse the influence of the demagnetization on the SASE process are in progress.
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