Taiwan Photon Source (TPS) is a newly constructed 3GeV synchrotron light source which ground breaking began February 2010. Its Booster beam commissioning and hardware improvement started at August 2014 and ramped to 3 GeV successfully in December 16 2014. Soon the stored beam in the storage ring had achieved 5 mA in December 31[1][2]. The BPM electronics Libera Brilliance+ [3][4] are adopted for booster and storage ring of TPS. The provided BPM data is useful for beam commissioning where it can be used to measure beam position, rough beam intensity along the longitudinal position and also for tune measurement. This report summarizes BPM commissioning and measurement during beam commissioning. INTRODUCTION The TPS is a state-of-the-art synchrotron radiation facility featuring ultra-high photon brightness with extremely low emittance [5]. The TPS accelerator complex consists of a 150 MeV S-band linac, linac to booster transfer line (LTB), 0.15–3 GeV booster synchrotron, booster to storage ring transfer line (BTS), and 3 GeV storage ring. The Storage Ring’s circumference is 518.4 meters with 24 DBA lattice and 6fold symmetry; the booster has 6 FODO cells and its circumference is 496.8 meters. The booster and the storage ring share the same tunnel in a concentric fashion. During 4 years of construction period, civil constructions had been completed in early 2013. At September 2014, booster BPM commissioning had committed with beam commissioning. After some hardware improvement such as power supply tuning, chamber and magnet re-alignment, demagnetization of chamber, kicker and septum improving and etc., booster had achieved beam ramped to 3 GeV at December 16 2014. Later, after improving field leakage of Booster extraction DC septum, we had a 5-mA stored beam on Dec. 31 2014. Diagnostic system played a helpful role to provided beam profile and information to improve or tune subsystem to make progress quickly during beam commissioning. This report will focus on the BPM related environment, functionalities and measurement. BPM FUNCTIONALITIES AND COMMISSIONING The TPS storage ring is divided into 24 cells and there are 7 BPMs per cell; the booster ring has six cells where each cell is equipped with 10 BPMs. Booster button BPM shapes 35x20 mm elliptical and button diameter 10.7 mm. The calibration factor Kx and Ky is 8.25 and 9.66 mm respectively. There are two kinds of BPM for storage ring as Fig. 1 shown: one is standard button BPM shapes 68x30 mm elliptical and diameter 7.4 mm at arc section; the other is primary BPM shapes 64x16 mm racetrack and diameter 7.4 mm at straight line. The calibration factor Kx/Ky is 13.8/12.73 and 6.58/8.89 mm for standard and primary BPM respectively. Figure 1: Mechanical drawings of standard type and primary type BPM for TPS storage ring. The conceptual functional block diagram of the BPM electronics is shown in Fig. 2. It will provide several data type for different application. ADC and TBT data is acquired on demand by trigger; 10 Hz slow data is for DC average orbit and 10 kHz fast data could be applied for booster ramping orbit or fast orbit feedback application. It is also embedded with EPICS IOC for control, monitor and configuration. The timing AMC module would provide functionalities of synchronization, trigger, interlock and post-mortem. To support operation of the BPM electronics, functionalities like cold start, shutdown, housing, control system interface should meet the requirements. The delivered units also had been performed functionality and performance test to ensure compliance with this specification. Figure 2: BPM platform functional block diagram. At September, the first turn of the booster beam had achieved soon after correctors steering. There are only Proceedings of IBIC2015, Melbourne, Australia Pre-Release Snapshot 17-Sep-2015 10:30 TUPB068 BPMs and Beam Stability ISBN 978-3-95450-176-2 1 Co py rig ht © 20 15 CC -B Y3. 0 an d by th er es pe ct iv ea ut ho rs Pr eRe lea se Sn ap sh ot 17 -S ep -2 01 5 10 :3 0 few buttons of BPM found to have contact problems quickly by observing ADC data with extremely low count compared to other buttons. The real BPM calibration factor was agreed with the designed values by measuring and comparing the optical function of machine model. The first turn and accumulated beam of the storage ring soon obtained without correctors after injection started. It was also found that there are some cabling problems during machine measurement and optimization. Button B and C of two BPMs were cross connected. The cables of BPM 24_4 and 24_6 were also in wrong order. Besides, the LOCO fitting for BPM calibration factor showed that there were three primary BPMs which sensitivity Kx/Ky were almost only the half as shown in Fig 3. It was caused by incorrect settings of sensitivity factor of these three BPMs. Primary BPM are generally installed at straight line for normal ID. However, vertical beam duct height enlarge rather than reduce to transition to large aperture of vacuum duct of SRF modules. Therefore, standard BPMs are installed rather than primary BPMs installed at these sites. Figure 3: BPM calibration factor fitting results for LOCO. There are three BPM that should be primary BPM but actually standard BPM. BOOSTER BPM MEASUREMENT There are 60 sets of phase-trimmed 0.240” form polyethylene coaxial cables connected between the buttons and BPM electronics for booster. The trimmed BPM cables have the phase difference less than ±3 ̊ and attenuation difference less than 0.1 dB. Different BPM data flow will be demonstrated for different applications in this section. ADC Raw Data The ADC raw data is useful for checking the timing of the beam and beam property especially in the first turn. The phase delay due to time difference when beam travel pass the buttons along the ring could align by ADC clock offset. Fig. 4(a) shows that the first beam passing through the injection septum and kicker and arriving the 1 BPM of the booster ring when beam first steered pass through; (b) ADC data as the beam had stored in the booster. (a) (b) Figure 4: (a) The ADC data when beam passes through the 1 BPM of the booster synchrotron on the first day of Booster commissioning. (b) The ADC data as the beam had stored in the booster. First-turn Application BPM electronics provides single pass mode for calculating first turn trajectory from ADC data. However, vast beam losses and ADC DC offset up to 100 count will result in worsen signal to noise ratio and position calculation offset error. Therefore, a soft IOC would be applied to acquire more precise first turn trajectory from ADC raw minus DC offset. Fig. 4 shows the first turn orbit trajectory and sum along 60 BPMs. Horizontal trajectory shapes like dispersion function due to energy drift from Linac modulator. Figure 5: First turn horizontal, vertical trajectory and sum along 60 BPMs of booster. Slow & Fast Orbit Data The BPM electronics also provide 10 Hz slow and 10 kHz fast position data to measure average stored beam orbit. Figure 6 shows the FA orbit variation for DC and AC mode respectively. At DC mode, 60 Hz orbit 100 200 300 400 500 600 700 -1000 -500 0 50