| Paper |
Title |
Page |
| WEPCH015 |
Measurement and Correction of Dispersion in the VUV-FEL
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1951 |
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- E. Prat, W. Decking, T. Limberg
DESY, Hamburg
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Increase in transverse beam size in the undulator caused by dispersive effects is one of the major limitations for the operation of FLASH, the VUV-FEL at DESY. Sources of the (spurious) dispersion are field errors and stray magnet fields in the undulator beam line as well as spurious dispersion created upstream of the undulator by, for instance, rf coupler kicks, magnet misalignments and field errors. The impact of these errors on dispersion generation depends on the actual operating conditions of the accelerator, so the dispersion must be measured and controlled frequently. In this paper we present numerical studies of spurious dispersion generation, first dispersion measurements and correction results.
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| WEPCH016 |
Spurious Vertical Dispersion Correction for PETRA III
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1954 |
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- G.K. Sahoo, K. Balewski, W. Decking
DESY, Hamburg
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Spurious vertical dispersion, arising due to the misalignment and rotational errors of magnets in synchrotron radiation sources with low emittances, are highly undesirable as this contributes to the vertical beam size of the photon beam. This is a matter of concern in PETRA III, a 6GeV light source with a designed horizontal emittance of 1nm.rad and 1% emittance coupling. It has a hybrid lattice of FODO and DBA cells, which will be installed in one-eighth of the existing PETRA II ring. In this paper local and global vertical dispersion corrections are discussed. The global vertical dispersion is corrected using vertical corrector magnets (may also consider 12 skew quadrupole magnets), and the skew quadrupoles are used for local correction as well. Eight of them are placed close to the two damping wiggler sections used for minimizing the horizontal emittance. The remaining four are placed in the new octant with DBA cells where insertion devices are installed.
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| THPLS021 |
Dynamic Aperture Studies for PETRA III
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3320 |
| |
- Y.J. Li, K. Balewski, W. Decking
DESY, Hamburg
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PETRA III is a low-emittance storage ring dedicated to synchrotron radiation. For efficient injection in the top-up mode, the dynamic aperture has to be larger than 30 mm-mrad in the horizontal plane. This paper presents the choice of tunes and the optimization of the sextupole configuration. Tracking simulations have been performed, including the non-linear effects of 20 four-meters-long damping wigglers and a representative set of undulators. Misalignment and multipole errors are considered as well, leading to specifications for the magnet design and alignment procedure.
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