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- S. Sakanaka, S. Asaoka, W. X. Cheng, K. Haga, K. Harada, T. Honda, T. Ieiri, S. Isagawa, M. Izawa, T. Kageyama, T. Kasuga, M. Kikuchi, Y. Kobayashi, K. Kudo, H. Maezawa, A. Mishina, T. Mitsuhashi, T. Miyajima, H. Miyauchi, S. Nagahashi, T. T. Nakamura, H. Nakanishi, T. Nogami, T. Obina, K. Oide, M. Ono, T. Ozaki, C. O. Pak, H. Sakai, Y. Sakamoto, H. Sasaki, Y. Sato, T. Shioya, M. Tadano, T. Takahashi, S. Takasaki, Y. Tanimoto, M. Tejima, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, S. Yamamoto, S. I. Yoshimoto
KEK, Ibaraki
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Two synchrotron light sources are in operation at the High Energy Accelerator Research Organization (KEK): the Photon Factory (PF) storage ring and the Photon Factory Advanced Ring (PF-AR). The 2.5-GeV PF storage ring was largely upgraded during March to September, 2005. Through this upgrade, existing ten straight sections were extended in length, and four short-straight sections were newly created. New short-period undulators were then installed in the new sections. Other developments, including a top-up injection, are in preparation. The other light source, the 6.5-GeV PF-AR, is routinely operated with a single bunch. It provides high-flux hard X-rays for research including time-resolved pulse X-ray experiments. In the PF-AR, four in-vacuum undulators and one elliptically polarized multipole wiggler are in operation. Moreover, a new in-vacuum undulator was installed in summer, 2006. Some operational developments were also carried out. In this presentation, we report both hardware and operational advances of the PF and the PF-AR storage rings.
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The photon factory advanced ring (PF-AR) is a dedicated single bunch light source at KEK, however, some users require multi-bunch operation for high intensity x-ray beams. The old transverse damping system can suppress only one (or two) bunches, while new multi-bunch feedback system has been successfully tested to a maximum of 64 bunches. Both analog and digital transverse feedback loop has been tested at AR to store multi-bunches. Long cables are used to delay the bunch position error signal from BPM buttons for analog feedback control loop. Betatron phase advance between stripline kicker and BPM are selected to be around 90 deg. For digital feedback loop, it based on a FPGA test board. Bunch position error signal sampled by ADC, filtered by 10-tap FIR filter implemented in FPGA and send to DAC output for correction. FIR filter is well designed to increase the system dynamic range. Digital delay can also be implemented inside FPGA instead of long cable delays. Maximum beam current of 97mA has been achieved for several bunches’ storage, betatron oscillation of the stored beam can be suppressed well.
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