NSRRC Activity Report 2023

092 NSRRC ACTIVITY REPORT 2023 Taiwan Photon Source (TPS) Machine Parameters of the TPS The Taiwan Photon Source (TPS) has been in operation for seven years since it officially opened to user proposals in 2016. Within the TPS, the storage ring includes a strong focusing double bend achromatic lattice that features low emittance, top-up injection, SRF module operation, long straight sections and high stability. Table 3 lists the major parameters of the TPS storage ring for current operation. The TPS accelerators include concentric storage rings and booster rings in the same tunnel due to the limited space on the campus and the consideration of energy savings. Beam Energy (GeV) 3 Circumference (m) 518.4 Current (mA) 500 Number of Buckets 864 Beam Emittance (ε x /ε y ) (nm-rad.) 1.6/0.016 Momentum Compaction (α 1 /α 2 ) 0.0024/0.0021 Tunes ( ν x / ν y ) 26.15/14.23 Lifetime (hour) > 8 Table 3 : Main parameters of the TPS storage ring. Statistics of TPS Machine Operation The TPS became operational for users in the last quarter of 2016 with a beam current of 300 mA, which was raised to 400 mA in December 2017 and was then regularly operated before being increased to 450 mA on the last day of 2020. In 2021, the stored beam current reached an operating current of 500 mA. The COVID-19 pandemic has caused delays in the delivery of several key components for both Phase-II and Phase-III beamlines. Despite these challenges, through dedicated collaboration between venders and NSRRC staff, 15 beamlines have been available to users in 2023. The scheduled and delivered user times and availability are shown in Fig. 4 on a quarter-to-quarter basis since 2017. In 2023, the annual availability was 98.9%, with a scheduled user time of 4,791 hours. The MTBF reached a record high of 191.64 hours, as shown in the data of Fig. 5 describing the annual availability. Downtime and Failure Analysis of the TPS In 2023, there were 24 beam trips and 50.79 hours of total downtime. The contributions from each subsystem of the TPS facility to this downtime are illustrated in Figs. 6 and 7 . The subsystem involving most beam trips and downtime is the SRF system, with this fragility attributed to the high current operation and over 0.5 megawatts of power that are applied to the beam within a 4.5 K cryogenic system. In recent years, the TPS and TLS linear accelerator systems have exhibited similar performance characteristics. However, aging phenomena have been observed in TLS Klystrons, resulting in the failure of electron beam injection into the TLS booster ring. Consequently, the operation mode of the storage ring has changed to decay mode. This issue was addressed by changing Klystron suppliers. The TPS linear accelerator system will adopt a similar approach to replace the Klystron supplier. Nonetheless, the overall reliability of these subsystems has gradually improved in recent years to achieve very stable operation and prolong the MTBF. (Reported by Hung-Jen Tsai) Fig. 4 : User time and beam availability of the TPS from 2017 onward.