| Paper |
Title |
Page |
| TUPP001 |
Alternating Gradient Operation of Accelerating Modules at FLASH
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1523 |
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- V. Ayvazyan, G. Petrosyan, K. Rehlich, S. Simrock, E. Vogel
DESY, Hamburg
- H. T. Edwards
Fermilab, Batavia, Illinois
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The free electron laser in Hamburg (FLASH) is a user facility providing high brilliant laser light for experiments. It is also an unique facility for testing the superconducting accelerator technology for the European XFEL and the international linear collider (ILC). The XFEL offers several beam lines to users. Within limits given by the beam delivery system the bunch pattern and beam energy should be adjustable independent for each beam line suggesting a time sliced operation. The ILC is focused on the highest gradients possible. FLASH accelerates beam at 5 Hz repetition rate. During accelerator studies the operation of the last accelerating modules with 10 Hz and alternating rf pulses has been established proving the feasibility of a time sliced operation at the XFEL. The rf pulses synchronous to the 5 Hz rf pulses are used for FEL operation whereas the gradient of the remaining rf pulse can be chosen independently and is used for long term high gradient operation gaining experience for the ILC. The operation of two different gradients within a single rf pulse is also available. The paper describes the technical setup, the rf control performance and the operational experience.
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| THPP114 |
LHC Transverse Feedback Damping Efficiency
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3632 |
| |
- G. Kotzian, W. Höfle
CERN, Geneva
- E. Vogel
DESY, Hamburg
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A simulation model has been developed to predict the damping efficiency of the LHC transverse feedback system in the presence of coupled bunch instabilities and under realistic assumptions for the injection error. The model tracks both the centre of gravity of a bunch and the r.m.s beam size during and after injection. It includes the frequency characteristic of the transverse feedback system. Nonlinearities in the beam optics will cause the bunches to filament and lead to an increase of the transverse emittance after injection. The resistive wall instability reduces the effectiveness of the transverse feedback by slowing down the damping process. Possibilities for enhancing the performance of the feedback system by signal processing schemes are outlined.
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