198 The operation statistics since the facility was opened to users are shown in Fig. 1. In 2008, the total operation time of the accelerator complex was 5078.5 hours. The operation time of the storage ring was 5063.4 hours, of which 79.7% (4037.8 hours) was made available to the users. The down time resulting from failure accounted for 0.76% (30.7 hours) of the user time; in 2008, no great loss of user time exceeding several hours occurred. Since 2004, there has been no injection time because top-up injection was introduced. Concerning user service operation, the high availability (ratio of net user time to planned user time) was achieved, e.g., 99.0% in 2008. The total tuning and study time of 1010 hours was used for machine tuning, and 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 time: percentages 18.7% in the multi-bunch mode, 44.2% in the several bunch mode, such as the 203-bunch mode (203 equally spaced bunches) and 37.1% in the hybrid filling mode such as a 1/14- partially filled multi-bunch with 12-isolated bunches. In 2008, the several bunch mode was the dominant filling mode. In particular, 203-bunch mode reached 24.1% 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 purity better than 10 -10 is routinely maintained in the top-up operation. Table III shows a summary of the beam filling patterns. Table IV shows a summary of the useful beam parameters of the storage ring. decade. In order to design a detailed plan, the working group for the SPring-8 upgrade plan was formed on October 10, 2008, comprised of scientists and engineers of RIKEN and JASRI who will lead the next generation. The working group has started closely examining the upgrade processes needed for the accelerator complex, X-ray sources, and effective utilization of the SPring-8. Currently, an X-ray free electron laser (XFEL) facility is being constructed at the SPring-8 campus with completion slated for 2011. Owing to juxtaposing XFEL, the SPring-8 will become a unique large-scale third-generation synchrotron radiation facility, forming a center-of-excellence for advanced photon science. Also currently under construction is the electron beam transport system designed to inject the high quality electron beam generated by the XFEL linac to the SPring-8 storage ring. 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Accelerator Operation Time Storage Ring Operation Time Tuning & Study (Acc. & BL) Injection Failure User Time Planned Time Availability (%) 2008 1286.0 4189.6 5051.6 5167.5 5456.1 5542.9 5419.5 5759.2 5317.1 5026.2 5027.9 1270.6 4135.4 4863.9 4972.9 5340.6 5484.1 5328.5 5736.7 4781.3 5008.5 5019.2 304 1457.6 1624.2 1815 1276.5 1394.9 1245.8 1085.9 1559.2 1193.6 1100.3 50 110 95.2 70.4 59.3 60.8 39.2 0 0 0 0 26 110 57.2 88.7 87.1 190.5 208.5 82.4 59.7 42.5 27.6 906 2512 3275 3193.4 4033.2 3896.7 3926 4590.9 3698.2 3790.1 3900 984 2712 3432 3352 4176 4152 4176 4680 3762 3840 3936 97.2 96.7 98.2 97.4 98 95.3 95 98.1 98.3 98.7 99.1 5078.5 5063.4 1010 0 30.7 4037.8 4080 99 0 1000 2000 3000 4000 5000 6000 Hours Tuning & Study Injection Failure UserTime Fig. 1. Operation statistics since the facility became available to users. II. Machine Operation II. Machine Operation
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