| Paper | Title | Page |
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| TUPC116 | Field Characterization of XFEL Quadrupole Magnets | 1338 |
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The European X-ray free electron laser (XFEL) will be one of the most advanced light source facilities in Europe and produce high intensity laser light of wavelengths down to 0.1 nm*. The laser light is produced and amplified by electrons moving through long undulator systems, each consisting of several 5 m long segments. After each undulator segment an adjustable quadrupole magnet is placed to focus the electron beam. For optimum control of the laser light the centre of the quadrupoles need to be positioned along a straight line with an accuracy of 0.001 mm which only can be reached by beam based alignment (BBA). Prior to the BBA procedure the magnets need to be aligned along the beam path, therefore the centre position of the magnet has to be determined relative to fiducials placed on the magnet body with an accuracy of approximately 0.01 mm. A rotating coil system has been set up at the Manne Siegbahn Laboratory to characterize the magnetic field between the four magnetic poles and to measure the stability of the magnetic centre. The accuracy of this instrument and procedures of how to fiducialize the magnetic centre are presented.
*European XFEL technical design report, edited by M. Altarelli et. al., DESY 2006. |
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| WEPC101 | Improved Homogeneity of Permanent Magnets for Undulators and Wigglers | 2234 |
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| The homogeneity of permanent magnets for use in undulators and wigglers were significantly improved in close collaboration between industry and scientific institutes throughout the last three years. Magnets with a variation of less than ± 1% in remanence, ± 1° magnetic angle and ± 1% hot/cold-side effect can be produced now - a variation of the magnetic angle of less than ± 0.5 ° is possible for some products. The development was assisted by improved characterization equipment for magnetic dipole moment and magnetic inhomogeneities by the scientific partners, which was made available for industrial application at Vacuumschmelze. | ||
| WEPC118 | Study of Controllable Polarization SASE FEL by a Crossed-planar Undulator | 2282 |
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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. | ||
| WEPC129 | Undulator Demagnetization due to Radiation Losses at FLASH | 2308 |
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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. | ||
| WEPC133 | Status of the PETRA III Insertion Devices | 2320 |
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| The PETRA storage ring is presently reconstructed towards a third generation light source. In total, 14 undulator beamlines will be available in the new octant of the machine. We report on the status of Petra III undulators. Three prototypes with 29mm period length, two 2m and one 5m long device have been investigated by mechanical and magnetic measurements. The prototype results are the basis for the refined design of the remaining 8 planar devices which are in the procurement phase. We present preliminary magnetic results of the prototypes and also report on the APPLE–2 and the in-vacuum undulator for PETRA III. |