| Paper | Title | Page |
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| TUOAB01 | Lattice Design of a Very Low-emittance Storage Ring for SPring-8-II | 942 |
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The design work for an upgrade project of the SPring-8, the SPring-8-II, is in progress. Its ultimate goal is to provide a superior brilliance of photons by reducing emittance of electrons until a diffraction limit. A multi-bend lattice has been adopted for the emittance reduction; a double-bend lattice (natural emittance of 2000 pmrad at 6 GeV), a triple-bend lattice (400 pmrad) and a quadruple-bend lattice (170 pmrad) were designed step by step for studying its feasibility*. For an additional emittance reduction, beam dynamic issues for a sextuple-bend lattice have been examined for the first candidate. In this case, the natural emittance is about 70 pmrad. The dynamic aperture has been enlarged by studying beam dynamic phenomena caused by nonlinear dispersion, nonlinear chromaticity, nonlinear resonance, etc., and by optimizing linear and nonlinear optics. The lattice design for the coming upgrade of SPring-8 will be presented in detail.
* K. Soutome et al., "Design Study of a very Low-emittance Storage Ring for the Future Upgrade Plan of SPring-8", Proc. of IPAC10, WEPEA032, p. 2555 (2010). |
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Slides TUOAB01 [4.812 MB] | |
| WEPC069 | Impact of Nonlinear Resonances on Beam Dynamics at the SPring-8 Storage Ring | 2181 |
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| For a low emittance storage ring like high brilliant light sources, the improvement of nonlinear beam dynamics is necessary for the stable operation, or for providing large dynamic aperture and momentum acceptance for efficient injection and long Touschek lifetime. At the SPring-8 storage ring it is observed that injection efficiency is affected by the gap heights of the magnet arrays of the in-vacuum insertion devices. The fact that the injected beam of fundamentally oscillating in horizontal direction is limited by the vertical aperture means that coupling resonances influence the beam dynamics. To clarify the phenomena, we studied the nonlinear beam dynamics of transverse betatron motion by means of turn-by-turn method. Then, we found some nonlinear coupling resonances, such as the one by skew sextupole field, are excited to enhance vertical oscillation and to deteriorate the injection efficiency. By analyzing these results, we developed measures to suppress the effect of the nonlinear coupling resonances and to improve the injection efficiency. | ||
| THPC032 | Current Status of SPring-8 Upgrade Plan | 2981 |
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| The SPring-8 upgrade plan has been discussed. The main goal is to replace the storage ring in the existing tunnel so that the resulting emittance will get as close to the diffraction limit in hard x-ray region as possible. For 10 keV photons, for instance, the diffraction limit corresponds to the emittance of as small as 10 pm.rad. For the challenging goal, the new ring features a multi-bend lattice with damping wigglers, which presumably enables us to reduce an emittance by two orders of magnitudes or more compared with the current double-bend lattice without damping wigglers. Up to now, a six-bend lattice has been mainly studied, which is supposed to generate a natural emittance of 60–70 pm.rad for 6 GeV. In addition, damping wigglers and coupling control should assist to reduce the emittance even more for approaching the ultimate goal. The major modification requires not only an advanced lattice design via manipulation of non-linear beam dynamics but also extensive technological developments in almost every component such as magnets, monitors, and RF systems. The overall review of the upgrade plan, including some detailed discussions on the critical issues, will be presented. | ||