Author: Ohkuma, H.
Paper Title Page
TUPPC013 Optimization of Lower Emittance Optics for the SPring-8 Storage Ring 1182
  • Y. Shimosaki, K.K. Kaneki, M. Masaki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, S. Takano, M. Takao
    JASRI/SPring-8, Hyogo-ken, Japan
  A design work of the present SPring-8 storage ring is in progress to improve its performance. The linear optics has been changed to reduce the natural emittance below the nominal of 3.4 nmrad at 8 GeV, and the nonlinear optics has been optimized with a genetic algorithm to suppress the amplitude-dependent tune shifts and to enlarge the dynamic aperture. As a preliminary study, the optics with the natural emittance of 2.4 nmrad at 8 GeV has been examined, theoretically and experimentally. In this optics, 1.5 times higher brilliance for 10 keV photons than the present can theoretically be expected for the standard undulator beamline. The improved optics design and its beam performance will be presented in detail. In this presentation, a optics for a future upgrade of the SPring-8 (SPring-8 II) will not be discussed, which is a full-scale major lattice modification, while the method we used in optimizing the nonlinear optics can also be adopted to the SPring-8 II*.
* Y. Shimosaki et al., "Design Study of Nonlinear Optics for a Very Low-emittance Lattice of the SPring-8 II," these proceedings.
TUPPC014 Design Study of Nonlinear Optics for a Very Low-emittance Lattice of the SPring-8 II 1185
  • Y. Shimosaki, K.K. Kaneki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, M. Takao
    JASRI/SPring-8, Hyogo-ken, Japan
  A feasibility of a very low-emittance storage ring has been studied for an upgrade project, SPring-8 II. Its ultimate goal is to provide a superior brilliance for 0.5 ~ 100 keV photons. A sextupole bend lattice with the natural emittance of 70 pmrad at 6 GeV has been examined as the first candidate*. The nonlinear optics has been optimized to enlarge the dynamic aperture by correcting nonlinear resonances based on an isolated resonance Hamiltonian with thick lens approximation, and by non-interleaved sextupole method. A genetic algorithm, which has been examined to improve the performance of the present SPring-8**, will be adopted for detailed optimization of the tunes and sextupole strength to adjust the non-interleaved scheme and to correct higher order resonances. The correction scheme of nonlinear optics and its results will be presented in detail.
*Y. Shimosaki et al., IPAC’11, TUOAB01, p. 942 (2011).
**Y. Shimosaki et al., "Optimization of Lower Emittance Optics for the SPring-8 Storage Ring", these proceedings.
TUPPC015 Local Modification of Lattice of a Long Straight Section for Installing Small Gap In-vacuum Undulators at SPring-8 1188
  • K. Soutome, T. Fujita, K. Fukami, K.K. Kaneki, C. Mitsuda, H. Ohkuma, M. Oishi, Y. Okayasu, S. Sasaki, J. Schimizu, Y. Shimosaki, M. Shoji, M. Takao, Y. Taniuchi, C. Zhang
    JASRI/SPring-8, Hyogo-ken, Japan
  • M. Hasegawa, K. Kajimoto, T. Nakanishi
    SES, Hyogo-pref., Japan
  In the SPring-8 storage ring there are four magnet-free long straight sections (LSS) of about 30m. Recently we locally modified one of these sections by installing two quadrupole-triplets and divided it into three sub-sections. The vertical beta at the middle of each sub-section was lowered to 2.5m so that small gap in-vacuum undulators with a short period (min. gap: 5.2mm, period: 19mm) can be installed to build a high performance beamline for inelastic X-ray scattering. After modifying the lattice, however, the symmetry of the ring is lowered and, in general, it becomes difficult to keep sufficient dynamic aperture (DA) and momentum acceptance (MA). We solved this problem by combining the betatron phase matching, local chromaticity correction in LSS and cancellation of non-linear kicks due to sextupoles used for this correction. We could then recover DA and MA to almost the same level for the original one. The beam commissioning of the new lattice has successfully been finished, and from September 2011 it is used in user-operation. We will report our method of realizing a storage ring lattice having a very low symmetry and review the operation performance of the modified lattice.  
TUPPP015 Status and Recent Progress of SPring-8 1638
  • H. Ohkuma
    JASRI/SPring-8, Hyogo-ken, Japan
  The SPring-8 is an 8 GeV synchrotron radiation facility that has been in operation since 1997. The SPring-8 has been operated well and total user time has reached more than 53,700 hours, 75% of the total operation time. The average user time per year is about 4,000 hours. The average availability is about 98% in the past 15 years. The operational status and recent progress overview of SPring-8 is presented: the local lattice modification of 30-m long straight section for installing small gap (min. gap is 5.2 mm) in-vacuum undulators, the emittance coupling correction for the vertical beam size reduction, the test operation of low energy operation for the energy saving, and the study of lower emittance optics for the present SPring-8 storage ring. An outline of a future upgrade with a full-scale major lattice modification is also presented. We also present a little about recent progress of SPring-8 injecting accelerators.