| Paper |
Title |
Page |
| WEPC003 |
Coupling Control at the SLS
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1983 |
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- A. Streun, Å. Andersson, M. Böge, A. Luedeke
PSI, Villigen
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The vertical beam size measurement at the Swiss Light Source (SLS) is based on vertically polarized visual light and allows to verify a vertical emittance of a few pm rad, resp. an emittance ratio in the 10-4 range obtained in 400 mA top-up user operation mode by tuning the lattice by means of 24 skew quadrupoles. Suppression of betatron coupling by local and global coupling correction prevents losses of Touschek scattered particles at the narrow vertical gaps of the in-vacuum undulators and thus protects these devices and increases beam lifetime, resp. the top-up interval. We will report on our experience with the beam size monitor, on the method of coupling control and on the achievements in vertical emittance and beam lifetime.
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| THPC139 |
Properties of X-ray Beam Position Monitors at the Swiss Light Source
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3312 |
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- T. Wehrli, M. Böge, J. Krempasky, E. D. van Garderen
PSI, Villigen
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Tungsten blade type X-ray beam position monitors (X-BPMs) are widely used at the SLS to stabilize the photon beam position at the the micron level. Various slow (~0.5 Hz) photon beam position feedbacks (SPBPFs) being an integral part of the global orbit feedback system have been in operation for several years. They are solely based on one X-BPM reading assuming that the photon beam movement is dominated by angle changes of the electron beam. This paper reports on the operation of the first SPBPF using two X-BPMs. This allows the separation of positional and angular variations of the electron beam, which is of special importance for the recently commissioned PolLux dipole beamline, as it is mostly sensitive to position changes. Correlations between the electron beam movement and the X-BPM readings are extensively analyzed in order to disentangle systematic errors of the position determination and real orbit motion. Methods are presented on how to recognize and correct or even avoid large systematic errors of the X-BPMs. With this knowledge, the demanding requirements on X-BPM accuracy in case of a SPBPF utilizing two X-BPMs could be fulfilled for the first time at the SLS.
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