| Paper |
Title |
Page |
| MOPCH015 |
Impact of Undulator Wakefileds and Tapering on European X-ray FEL Performance
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83 |
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- I. Zagorodnov, M. Dohlus, T. Limberg
DESY, Hamburg
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The European X-ray Free-Electron Laser (XFEL) based on self-amplified spontaneous emission (SASE) requires an electron beam with a few kA peak current and a small-gap undulator system up to 250 m in length. The interaction between the high-current electron bunch and the undulator vacuum chamber affects the FEL performance. In this paper we estimate the induced wakefields in elliptical pipe geometry, taking into account the main geometrical variations of the chamber. To study the expected performance in the presence of the calculated wakefields, we are doing start-to-end simulations with the tracking codes ASTRA, CSRtrack and GENESIS. To compensate the wakefield impact on the FEL performance, an adiabatic change of undulator parameters is considered.
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| 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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