| Paper |
Title |
Page |
| MOPKF012 |
A 7T Multipole Wiggler in BESSY II: Implementation and Commissioning Results
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324 |
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- E. Weihreter, J. Feikes, P. Kuske, R. Müller, G. Wustefeld
BESSY GmbH, Berlin
- D. Berger
HMI, Berlin
- N.A. Mezentsev, V. Shkaruba
BINP SB RAS, Novosibirsk
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To generate hard X-ray beams for residual stress analysis and for magnetic scattering with the BESSY II SR source, a 7T wiggler with 17 poles has been implemented. Several problems had to be solved. Wake fields induced by smaller steps in the geometry of the radiation shield inside the beam chamber led to intolerable LHe consumption, which have been analysed numerically and then cured by improving the shield geometry. Much of the routine operation procedures are influenced by the unusually high radiation power level of max. 55 kW. For system protection an interlock system dumps the electron beam automatically in case of relevant error events. This wiggler is by far the strongest perturbation of the linear beam optics, breaking seriously the symmetry of the ring. Beam optical parameters including tune shift and beta beat have been measured to quantify these perturbations and develop efficient cures to limit the negative effects on beam lifetime and dynamic aperture. So far the wiggler is operated at 2.8 T and max. currents up to 250 mA in normal user shifts.
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| TUPKF011 |
First Tests of a HOM-Damped High Power 500MHz Cavity
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979 |
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- F. Marhauser, E. Weihreter
BESSY GmbH, Berlin
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A prototype high power 500 MHz copper cavity with three tapered circular waveguides for broadband higher order mode (HOM) damping has been fabricated especially for the use in 3rd generation synchrotron radiation sources. Low power impedance measurements are presented and compared with theoretical simulations to verify the expected HOM damping efficiency as well as the fundamental mode shunt impedance. After a careful cleaning and baking process to reduce the vacuum pressure the cavity has been conditioned at high power. All relevant parameters of the cavity are reported.
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