IPAC2017 - List of Authors (Kuske, P.)

Paper	Title	Page
WEPAB006	Performance Improvements of the BESSY II Storage Ring by Optimizing the Phase Acceptance	2571
	P. Kuske, J. Li HZB, Berlin, Germany
	Linear optics modifications in order to improve injec-tion efficiency and for the installation of two IDs in one straight section demand an optimization of the sextupole correction scheme. Four harmonic sextupole families were sufficient with the earlier 8-fold symmetric lattice. Today there are ten families of harmonic sextupole mag-nets in addition to the three families of chromatic sextu-poles. This paper describes our experimental approach to find better settings for these harmonic sextupoles based on the direct optimization of the injection efficiency with a longitudinal phase offset between storage ring and the injector - in our case a booster synchrotron. As demon-strated in the paper, the resulting improvement of the phase acceptance of the ring leads to increased momen-tum acceptance by suppressing 3rd order non-systematic resonances. This increases not only the injection effi-ciency for long bunches but also the Touschek lifetime, the largest contribution to the overall lifetime of low emittance storage rings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB006
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THPAB007	Short Bunches at the Transition From Strong to Weak Longitudinal Instability	3696
	P. Kuske HZB, Berlin, Germany
	The interaction of particles with their vacuum sur-roundings can lead to longitudinal instabilities of the whole bunch of particles. Most of these instabilities are strong and the growth rates are large compared to the damping rate. For a weak instability the opposite is true and with just a resistive impedance the instability would always be weak and independent of the bunch length. The interaction of a bunch with its own radiation emitted midway between parallel plates leads to a strong instabil-ity for long bunches and a transition to weak instability if the bunch length becomes shorter. This regime is ana-lysed numerically with a Vlasov-Fokker-Planck solver. The results are compared to recent observations at ANKA. An attempt is made to explain the remaining discrepan-cies by including higher order terms of the momentum compaction factor into these calculations. There are indi-cations that the simple model needs refinements in order to take radiation from upstream dipoles into account.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB007
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Paper

Title

Page

Performance Improvements of the BESSY II Storage Ring by Optimizing the Phase Acceptance

2571

P. Kuske, J. Li
HZB, Berlin, Germany

Linear optics modifications in order to improve injec-tion efficiency and for the installation of two IDs in one straight section demand an optimization of the sextupole correction scheme. Four harmonic sextupole families were sufficient with the earlier 8-fold symmetric lattice. Today there are ten families of harmonic sextupole mag-nets in addition to the three families of chromatic sextu-poles. This paper describes our experimental approach to find better settings for these harmonic sextupoles based on the direct optimization of the injection efficiency with a longitudinal phase offset between storage ring and the injector - in our case a booster synchrotron. As demon-strated in the paper, the resulting improvement of the phase acceptance of the ring leads to increased momen-tum acceptance by suppressing 3rd order non-systematic resonances. This increases not only the injection effi-ciency for long bunches but also the Touschek lifetime, the largest contribution to the overall lifetime of low emittance storage rings.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB007

Short Bunches at the Transition From Strong to Weak Longitudinal Instability

3696

P. Kuske
HZB, Berlin, Germany

The interaction of particles with their vacuum sur-roundings can lead to longitudinal instabilities of the whole bunch of particles. Most of these instabilities are strong and the growth rates are large compared to the damping rate. For a weak instability the opposite is true and with just a resistive impedance the instability would always be weak and independent of the bunch length. The interaction of a bunch with its own radiation emitted midway between parallel plates leads to a strong instabil-ity for long bunches and a transition to weak instability if the bunch length becomes shorter. This regime is ana-lysed numerically with a Vlasov-Fokker-Planck solver. The results are compared to recent observations at ANKA. An attempt is made to explain the remaining discrepan-cies by including higher order terms of the momentum compaction factor into these calculations. There are indi-cations that the simple model needs refinements in order to take radiation from upstream dipoles into account.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB007

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)