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Cheng, W.X.

Paper Title Page
THPCH092 Single-loop Two-dimensional Transverse Feedback for Photon Factory 3006
 
  • T. Nakamura, K. Kobayashi
    JASRI/SPring-8, Hyogo-ken
  • W.X. Cheng, T. Honda, M. Izawa, T. Obina, M. Tadano
    KEK, Ibaraki
 
  We installed a 500MS/s single-loop two-dimensional transverse bunch-by-bunch feedback system in the Photon Factory ring at KEK and the system is in operation at its user mode. The system composed of a single feedback loop; one skewed pair of BPM electrodes and one kicker stripline at skewed position to detect position and kick horizontally and vertically with a single signal line, and a SPring-8 feedback processor. Consequently, this system is easy to tune and cost effective. SPring-8 feedback processor employs FPGA that has enough computing power for processing more than 20-tap FIR filter required for newly developed two-dimensional feedback signal processing. We report the principle of the system, the result of test and the experience.  
THPCH093 Bunch-by-bunch Feedback for the Photon Factory Storage Ring 3009
 
  • W.X. Cheng, T. Honda, M. Izawa, T. Obina, M.T. Tadano, M. Tobiyama
    KEK, Ibaraki
  • K. Kobayashi, T. Nakamura
    JASRI/SPring-8, Hyogo-ken
 
  After the straight-section upgrade in 2005, the PF (Photon Factory) ring will start the top-up operation or the continuous mode in 2006. Previously the octupole magnets were used to suppress the transverse coupled bunch instability and RF modulation method to enhance the bunch length has been effectively used to suppress the longitudinal instabilities. However, such kind of methods are not suitable for the top-up operation, we are preparing active bunch-by-bunch feedback systems for both transverse and longitudinal plane. The transverse feedback system has been installed along with the straight-section upgrade, this system uses a FPGA based feedback processor board developed at the SPring-8, both horizontal and vertical signals are processed in a single control loop. For the longitudinal feedback, a two-port DAFNE type wide-band cavity has been designed and is now manufacturing, a digital signal processing part is under design, the whole system will start commissioning in autumn 2006.  
THPLS036 Results of the Straight-sections Upgrade of the Photon Factory Storage Ring 3365
 
  • T. Honda, S. Asaoka, W.X. Cheng, K. Haga, K. Harada, Y. Hori, M. Izawa, T. Kasuga, Y. Kobayashi, H. Maezawa, A. Mishina, T. Mitsuhashi, T. Miyajima, H. Miyauchi, S. Nagahashi, T. Nogami, T. Obina, C.O. Pak, S. Sakanaka, H. Sasaki, Y. Sato, T. Shioya, M. Tadano, T. Takahashi, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, S. Yamamoto
    KEK, Ibaraki
 
  At the 2.5-GeV ring of the Photon Factory (PF), a large reconstruction of the lattice around the straight sections* has been accomplished in 2005. As a result, four short straight sections of 1.5 m have been newly created, and the lengths of the existing straight sections have been much improved. For example, the length of the longest straight section has been extended to 9 m from 5 m. The optics has been optimized for installing short-period narrow-gap (in-vacuum) undulators at the new straight sections. The reconstruction work on the ring was held from March to September 2005. In the range over two-thirds of the storage ring, all the quadrupole magnets and all the beam ducts have been renewed and rearranged. Commissioning of the storage ring was started from the end of September 2005 and continued for one month. The operation for the user experiment was resumed from the end of October on schedule. Though we made no in-situ baking after the installation for the beam ducts, the vacuum scrubbing by the synchrotron radiation is running very well. The product of the beam lifetime and the beam current exceeded 700 A min for the operation current 450 mA at the end of December 2005.

*S. Asaoka et al. "New Upgrade Project for the Photon Factory Storage Ring", AIP Conf. Proc. 705, p161 (2004).