NSRRC Activity Report 2023

090 NSRRC ACTIVITY REPORT 2023 Status of TLS and TPS Accelerators Taiwan Light Source (TLS) Machine Parameters of the TLS T he Taiwan Light Source (TLS) passed its thirty-year anniversary of first light in 2023. After its inception in 1993, the TLS officially requested experimental proposals and opened to users with three soft X-ray beamlines: HSGM, LSGM and Seya. The original design of the TLS was a triple bend achromatic lattice with 1.3 GeV of beam energy and 200 mA of beam current. After several phases of upgrades, the accelerators have the features of 1.5 GeV with a maximum 360 mA stored beam current, top-up injection, a superconducting radio-frequency (SRF) cavity, a liquid- helium cryogenic system, superconducting wigglers (SCWs) and the most advanced feedback system for orbits and bunch-to-bunch stabilities. Several of these features were pioneering and unique features of the low-energy synchrotron community. The major parameters of the TLS are listed in Table 1 . Beam Energy (GeV) 1.5 Number of Buckets 200 Current (mA) 360 Horizontal Emittance (nm-rad.) 22 Vertical Emittance (pm-rad.) 88 Tunes ( ν x / ν y ) 7.303/4.175 Lifetime (hour) > 6 W200 U50 U90 EPU56 SWLS SW60 IASWA IASWB IASWC Type Hybrid Hybrid Hybrid Pure SC SC SC SC SC Period length (mm) 200 50 90 56 250 60 61 61 61 Photon energy (eV) 800–15k 60–1.5k 5–500 80–1.4k 2k–38k 5k–20k 5k–20k 5k–23k 5k–20k Table 1 : Main parameters of the TLS storage ring. Table 2 : Main parameters of the insertion devices used in the TLS. The sixfold symmetry storage ring included four room-temperature undulators, a wiggler, and five SCWs, equipping TLS with the most densely packed SCW configuration in the community. SCWs can generate high-energy photons for X-ray users. The parameters of the insertion devices are listed in Table 2 . Statistics of TLS Machine Operation At the initial top-up injection, the stored beam current was limited to 200 mA in early 2005 due to restrictions of the beam stabilities and capabilities of the RF system. The TLS gradually increased the stored beam current and reached 360 mA after the installation of the SRF module and upgraded the feedback system in 2010. The performance indicators for TLS operation from 2011 to 2023 are shown in Fig. 1 . This availability is defined as the ratio of the delivered user time to the scheduled user time, the mean time between failures (MTBF) is defined as the ratio of the scheduled user time to the number of system faults, and the beam stability index is defined as the shot-to-shot photon intensity variation in the diagnostic beamline with a ratio better than 0.1%. The annual availability was 98.99%, with a scheduled user time of 4,791 hours in 2023. The MTBF was 199.6 hours. Beam stability was maintained within 0.1% and 0.2%, with respective rates of 99.29% and 99.87%. One of the major replacements and decisions included changing the pulsed klystron vendor to Canon to improve the operation reliability and stability of the TLS Linac system in 2023.