Prapong Klysubun

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

Minimization of Nonlinear Effects of Insertion Devices at SPS Storage Ring

Nonlinear effects of insertion devices were studied for the Siam Photon Source (SPS) storage ring. Despite the fact that shimming technique was used to minimize the nonlinear components of magnetic field integral arising from random errors, the nonlinear dynamics effects still remain. It was found that calculated dynamic field integrals are largest in the 2.2 T Hybrid Multipole Wiggler (MPW). Dynamics effects of insertion devices are attributed to the wiggling trajectory of electron in the region of magnetic field roll-off due to finite pole width. For better and more effective operation of the SPS storage ring, multipole components of the dynamic field integral in the MPW have to be further reduced.

Analysis of Nonlinear Effects for IDs at the SPS Storage Ring

To generate intense and high energy synchrotron radiation at the Siam Photon Source (SPS) 1.2 GeV storage ring, two insertion devices (IDs), namely, a 2.2 T hybrid multipole wiggler (MPW) and a 6.5 T superconducting wavelength shifter (SWLS), have been installed and operated since 2013. The angular kicks due to the nonlinear effects generated by the IDs represented by kick maps were used in our analysis. The optics distortion was compared to the ones obtained from calculation using hardedge model and measurement results. In order to investigate the effects of IDs on the beam dynamics, Frequency Map Analysis (FMA) was employed. The effects of the IDs and their compensation are presented herewith.