Author: Kaneki, K.K.
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THPMR022 Non-linear Optimization of Storage Ring Lattice for the SPring-8 Upgrade 3440
  • K. Soutome, K.K. Kaneki, Y. Shimosaki, M. Takao
    JASRI/SPring-8, Hyogo-ken, Japan
  • H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  A project of upgrading the SPring-8 facility is ongoing to convert the present storage ring to a high-coherence hard X-ray source (SPring-8-II). To achieve the emittance value of less than 0.2 nmrad at 6 GeV, we adopted a 5-bend achromat lattice with dipoles having longitudinal field gradient. In this lattice the betatron phase between the two dispersion arcs was set to (2n+1)PI to suppress dominant harmful effects of chromaticity-correcting sextupoles. By detuning this phase, optimizing sextupole strengths in a cell and introducing octupoles, we obtained a sufficient dynamic aperture (DA) for beam injection even for the symmetry-broken ring having four long straight sections and a high-beta injection section. However, the off-momentum behavior such as the non-linear chromaticity still needs to be optimized to achieve the momentum acceptance (MA) of 3% or larger. We have thus been investigating the possibility to increase both the DA and MA by introducing several phase-matched sextupole pairs. The presentation will report the obtained results by this approach.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR022  
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