144 II. Machine Operation The operation statistics for the last five fiscal years are shown in Fig. 1. In FY2012, the total operation time of the accelerator complex was 5078.8 h. The operation time of the storage ring was 5063.1 h, 82.1% of which (4155.6 h) was made available for SR experiments. The downtime resulting from failure accounted for 0.94% (39.2 h) of the total user time. In FY2012, no great loss of user time exceeding several hours occurred. Since FY2004, top-up injection was introduced. Concerning user service operation, a high availability (ratio of net user time to planned user time), e.g., 98.9%, was achieved in FY2012. The total tuning and study time of 884 h was used for machine tuning, for the study of the linac, booster synchrotron and storage ring, and also for the beamline tuning and study. Operations in two different filling modes were provided for the following user time: 60.6% in the several-bunch mode, such as the mode of 29 equally spaced trains of 11 bunches, and 39.4% in the hybrid filling mode, such as the mode of 1/14-partially filled multi-bunch with 12-isolated bunches. In FY2012, there was no operation in the multi-bunch mode. The several-bunch mode was the dominant filling mode. The 203-bunch mode and the mode of 29 equally spaced trains of 11 bunches reached 29.8% and 30.9% of the total user time, respectively. The new hybrid filling mode of 11/29-partially filled multi-bunch with a 5.0 mA isolated bunch. For the hybrid filling mode, 1.0 mA, 1.6 mA, 3.0 mA, or 5.0 mA is stored in each isolated bunch. An isolated bunch impurity better than 10 -10 is routinely maintained in the top- up operation. Table I shows a summary of the useful beam parameters of the storage ring. Table II shows a summary of the beam filling patterns. Fig. 1. Operation statistics for the last five fiscal years. 0 1000 2000 3000 4000 5000 6000 Hours FY2012 Refill 5.2 Down Time 39.2 Achieved User Time 4155.6 Planning User Time 4200.0 Availability (%) 98.9 5078.8 Accelerator Operation Time 5063.1 Storage Ring Operation Time 884 Tuning & Study (Acc. & BL) 107.7 Mean Time Between Failures FY2008 FY2009 FY2010 FY2011 10.1 6.3 5.0 4.4 31.0 34.8 27.5 57 4110.9 4014.9 4071.6 4058.5 4152.0 4056.0 4104.0 4120.0 99.0 99.0 99.2 98.5 5150.1 5068.8 5125.6 4918.6 5133.3 5035.4 5096.3 4904.2 1008.2 1019.1 1026.6 803 153.8 122.9 178.4 117.7 Tuning Refill Down Time User Time Energy [GeV] 8 Number of buckets 2436 Tunes ( ν x / ν y ) 40.14 / 19.35 Current [mA]: single-bunch 12 multi-bunch 100 Bunch length ( σ ) [psec] 13 Horizontal emittance [nm·rad] 3.5 * Vertical emittance [pm·rad] 6.9 * Coupling [%] 0.2 RF Voltage [MV] 16 Momentum acceptance [%] Beam size ( σ x / σ y ) * [ μ m] Long ID section 297 / 10 ID section 303 / 6 BM1 section 108 / 13 ± 3 (± 240 MeV) / BM2 section 115 / 14 Beam divergence ( σ x ' / σ y ' ) * [ μ rad] Long ID section 13 / 0.7 ID section 12 / 1.1 BM1 section 57 / 0.6 / BM2 section 74 / 0.6 Operational chromaticities ( ξ x / ξ y +1 / +1 * * Lifetime [h] : 100 mA (multi-bunch) ~ 200 1 mA (single-bunch) ~ 20 Horizontal dispersion [m]: Long ID section 0.103 ID section 0.107 BM1 section 0.032 BM2 section 0.070 Fast orbit stability (0.1 – 200 Hz) [ μ m]: horizontal (rms) ~ 4 ~ 1 vertical (rms) * Assuming 0.2% coupling * * With bunch-by-bunch feedback ) Table I. Beam parameters of SPring-8 storage ring Table II. Filling patterns bunch current (mA) life time (h) 203 bunches 0.5 25 ~ 30 11 bunch-train × 29 0.3 35 ~ 50 11/29 - filling + 1 single bunch 1/7 - filling + 5 single bunches 1/14 - filling + 12 single bunches 5.0 (single) 40 ~ 50 3.0 (single) 18 ~ 25 1.6 (single) 18 ~ 25 4/58 - filling + 53 single bunches 1.0 (single) 18 ~ 25
home
- JP
- EN