174 II. Machine Operation II. Machine Operation The operation statistics for the last five fiscal years are shown in Fig. 1. In FY2010, the total operation time of the accelerator complex was 5125.6 hours. The operation time of the storage ring was 5096.3 hours, of which 79.9% (4071.5 hours) was used for SR experiments. The downtime resulting from failure accounted for 0.67% (27.5 hours) of the total user time. In FY2010, no great loss of user time exceeding several hours occurred. In 2004, top-up injection was introduced. Concerning user service operation, a high availability (ratio of net user time to planned user time), i.e., 99.2%, was achieved in FY2010. A total tuning and study time of 1026.6 hours 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 three different filling modes were provided for the following user times: 5.9% in the multi-bunch mode, 56.7% in the several bunch mode, such as the 203-bunch mode (203 equally spaced bunches), and 37.4% in the hybrid filling mode, such as the 1/14-partially filled multi-bunch mode with 12-isolated bunches. In FY2010, the several bunch mode was the dominant filling mode. In particular, the 203-bunch mode reached 30.9% of the total user time. For the hybrid filling mode, 1.0 mA, 1.4 mA, 1.6 mA, or 3.0 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. FY2006 FY2007 FY2008 FY2009 FY2010 Accelerator Operation Time Storage Ring Operation Time Tuning & Study (Acc. & BL) Refill Down Time Achieved User Time Availability (%) 5025.0 5012.3 1213.8 7.6 38.4 106.0 3770.0 3816.0 98.8 5063.6 5022.3 1065.0 9.5 29.2 14.4 3969.3 4008.0 99.0 5050.1 5133.3 1008.2 10.1 31.0 143.2 4110.9 4125.0 99.0 5068.8 5035.4 1019.1 6.3 34.8 122.9 4014.9 4056.0 99.0 5125.6 5096.3 1026.6 5.0 27.5 178.4 4071.6 4104.0 99.2 Planning User Time Mean Time Between Failures 0 1000 2000 3000 4000 5000 6000 Hours Tuning Refill Down Time User Time Energy [GeV] 8 Number of buckets 2436 Tunes ( ν ν x / ν ν y ) 40.135 / 18.345 Current [mA]: single bunch 12 multi bunch 100 Bunch length ( σ σ ) [psec] 13 Horizontal emittance [nm·rad] 3.4 * Vertical emittance [pm·rad] 6.8 * Coupling [%] 0.2 RF Voltage [MV] 16 Momentum acceptance [%] Beam size [ μ μ m]: ( σ σ x / σ σ y ) * [ μ μ m] Long ID section 294 / 10 ID section 301 / 6 BM section 107 / 13 Beam divergence [ μ μ rad]: ( σ σ x '' / σ σ y '' ) * [ μ μ rad] Long ID section 13 / 0.7 ID section 12 / 1.1 BM section 56 / 0.6 Operational chromaticities ( ξ ξ x / ξ ξ y ) +2 / +6 * * Lifetime [h] : 100 mA (multi-bunch) ~ 200 1 mA (single bunch) ~ 20 Horizontal dispersion [m]: Long ID section 0.103 ID section 0.107 BM section 0.032 Fast orbit stability (0.1 – 200 Hz) [ μ μ m]: horizontal (rms) ~ 4 vertical (rms) * Assuming 0.2% coupling for “Low Emittance Optics” * * With bunch-by-bunch feedback ± 3 (± 240 MeV) bunch current (mA) life time (h) Multi-bunch (160 bunch-train × 12) 0.05 ~ 200 203 bunches 0.5 25 ~ 30 11 bunch-train × 29 0.3 35 ~ 50 1/7 - filling + 5 single bunches 1/14 - filling + 12 single bunches 2/29 - filling + 26 single bunches 3.0 (single) 18 ~ 25 1.6 (single) 18 ~ 25 1.4 (single) 18 ~ 25 Fig. 1. Operation statistics for last five fiscal years. Table I. Beam parameters of SPring-8 storage ring Table II. Filling patterns
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