162 II. Machine Operation II. Machine Operation The operation statistics for the last five fiscal years are shown in Fig. 1. In FY2011, the total operation time of the accelerator complex was 4918.6 h. The operation time of the storage ring was 4904.2 h, 82.8% of which (4058.5 h) was made available for SR experiments. The downtime resulting from failure accounted for 1.4% (57 h) of the total user time; in November 2011, a great loss of user time was incurred owing to cooling water leak from the cooling pipe to the vacuum vessel of the in-vacuum undulator (ID47); consequently, a user time of 27.15 h was cancelled for the suspension of machine operation. 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., 98.5%, was achieved in FY2011. The total tuning and study time of 803 h was used for machine tuning, to study 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: 62.5% in the several-bunch mode, such as the mode of 29 equally spaced trains of 11 bunches, and 37.5% in the hybrid filling mode, such as the mode of 1/14-partially filled multi-bunch with 12-isolated bunches. In FY2011, 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 30.3% and 32.2% of the total user time, respectively. For the hybrid filling mode, 1.0, 1.4, 1.6, 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. 0 1000 2000 3000 4000 5000 6000 Hours FY2007 FY2008 FY2009 FY2010 FY2011 Refill 9.5 10.1 6.3 5.0 4.4 Down Time 29.2 31.0 34.8 27.5 57 Achieved User Time 3969.3 4110.9 4014.9 4071.6 4058.5 Planning User Time 4008.0 4152.0 4056.0 4104.0 4120.0 Availability (%) 99.0 99.0 99.0 99.2 98.5 5063.6 5150.1 5150.1 5125.6 4918.6 Accelerator Operation Time 5056.3 5133.3 5035.4 5096.3 4904.2 Storage Ring Operation Time 1065.0 1008.2 1019.1 1026.6 803 Tuning & Study (Acc. & BL) 148.4 143.2 122.9 178.4 117.7 Mean Time Between Failures Tuning Refill Down Time User Time Energy [GeV] 8 Number of buckets 2436 Tunes ( x / y ) 40.14 / 19.35 Current [mA]: single bunch 12 multi bunch 100 Bunch length ( ) [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 ( x / y ) * [ m] Long ID section 297 / 10 ID section 303 / 6 BM1 section 108 / 13 ± 3 (± 240 MeV) / BM2 section 115 / 14 Beam divergence ( x '' / y '' ) * [ rad] Long ID section 13 / 0.7 ID section 12 / 1.1 BM1 section 57 / 0.6 / BM2 section 74 / 0.6 Lifetime [h] : 100 mA (multi-bunch) ~ 200 1 mA (single bunch) ~ 20 Horizontal dispersion [m]: Long ID section 0.103 ID section 0.107 BM1 section 0.032 BM2 section 0.070 Fast orbit stability (0.1 – 200 Hz) [ m]: horizontal (rms) ~ 4 ~ 1 vertical (rms) * * With bunch-by-bunch feedbac ν ν ν ν σ σ σ σ σ σ μ μ σ σ σ σ μ μ μ μ * Assuming 0.2% coupling k Operational chromaticities ( ξ ξ x / ξ ξ y +1 / +1 * * ) bunch current (mA) life time (h) 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 4/58 - filling + 53 single bunches 1.0 (single) 18 ~ 25 Fig. 1. Operation statistics for the last five fiscal years. Table I. Beam parameters of SPring-8 storage ring Table II. Filling patterns
home
- JP
- EN