Siam Photon Source: Present Machine Status and Future Upgrades

Siam Photon Source, the Thailand synchrotron light source, has received several upgrades in recent years. Most important of which are the improvement of the positional stability of the stored electron beam, and the installation of 2 IDs, i.e. a 2.2 T hybrid multipole wiggler and a 6.5 T superconducting wavelength shifter, to extend the available SR spectrum into hard x-ray region. The beam stability improvement was achieved through several activities, including improving the BPM system, upgrading the existing corrector power supplies, and implementing global orbit feedback. The two new IDs provide higher-intensity and higher-energy (up to 25 keV) synchrotron light, which will be utilized for MX, high-energy SAXS, WAXS, XAS, and microtomography. Ongoing machine upgrades include increasing the energy of the booster and transport line to 1.2 GeV for full-energy injection and eventual top-up operation. Utilization of the electron beam is also being explored. A beam test facility, which extracts electron beam in the booster for characterizing high-energy particle sensors, as well as calibrating other beam diagnostic instruments, has been constructed and is now in operation. INTRODUCTION Siam Photon Source (SPS) has been in operation for synchrotron radiation users for 11 years. During these time the accelerator facilities have been continually improved. [1] In recent years, substantial improvements have been made, i.e. available photon energy has been extended into hard xray region. Positional stability of the photon beam, as well as machine reliability, have been markedly improved. Besides generating synchrotron radiation, electron beam itself is now utilized for characterization of high-energy particle detectors. MACHINE OPERATION In fiscal year 2016, which started from October 1, 2015 and ended on September 30, 2016, we had operated the 1.2 GeV storage ring in user mode of operation. The monthly operation had been such that the first 5 days of each month were reserved for maintenance, installation, repair, and machine study. The rest of the month were user beamtime. During these user beam periods the photon beam were provided to users 24/7. The electron beam was injected twice a day from 8:30 AM to 9:00 AM and from 8:30 PM to 9:00 PM. The maximum beam current was 150 mA. The number of user beamtime per day was 23 hours. A typical daily operation of the SPS is shown in Fig. 1. Figure 1: Example of daily SPS operation. The total number of user beamtime that was scheduled was 4,475 hours. We were able to deliver 4,343 hours, corresponding to Machine Availability of 97.1%. (Fig. 2) Mean Time Between Failures (MTBF) and Mean Time To Recover (MTTR) of FY 2016 are shown in Fig. 3. Figure 2: Operation statistics from FY 2006 to FY 2016. Figure 3: FY 2016 monthly MTBF and MTTR. In Fig. 3, the MTTR of September 2016 is significantly higher than that of the other months. The reason is that the failure was the vacuum leakage at the front-end of BL1 ___________________________________________ * pklysubun@slri.or.th WEPAB085 Proceedings of IPAC2017, Copenhagen, Denmark ISBN 978-3-95450-182-3 2770 Co py rig ht © 20 17 CC -B Y3. 0 an d by th er es pe ct iv ea ut ho rs 02 Photon Sources and Electron Accelerators A05 Synchrotron Radiation Facilities beamline, which took considerable amount of time to recover. In FY 2016 there were 60 instances of beam trip (Fig. 4). The most frequent cause came from magnet power supplies (14 times), followed by electrical system (8 times). The RF system, which caused considerable downtime in the previous year, contributed only 12% this year (7 times). This is a good indication that the problems associated with the solid-state power amplifier had finally been resolved. Figure 4: Causes of machine trip in FY 2016. MACHINE IMPROVEMENTS 2nd Storage Ring RF System A new RF system was successfully installed in the storage ring during 2016 Machine Shutdown. [2] The new cavity (Fig. 5) has maximum cavity voltage of 300 kV. (The old one has 125 kV.) The new amplifier (Fig. 6) has maximum power of 80 kW. (The old one has 30 kW.) The new system will allow SLRI to operate the superconducting wavelength shifter (SWLS) at its maximum magnetic field of 6.5 Tesla, which will in turn increase both the flux and the photon energy delivered to BL7 beamline. Figure 5: The new 300 kV RF cavity. Table 1: Main Parameters of the 300 kV Cavity Parameters Values Resonant frequency 118 MHz Maximum cavity power 30 kW Maximum coupler power 120 kW Shunt impedance 1.56 MΩ Quality factor Q