| Paper | Title | Page |
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| MOPAN036 | Longitudinal Feedback System for the Photon Factory | 233 |
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| In the KEK-PF, longitudinal coupled-bunch instabilities are suppressed by means of the RF phase-modulation technique during the users operation. This method is very effective not only to suppress the instabilities but also to enlarge the beam lifetime. Together with the feasibility study for top-up operation, bunch-by-bunch feedback system have been developed. A two-port longitudinal kicker based on dafne-type cavity were designed and installed in the storage ring in the summer of 2006. FPGA-based signal processing part is under development based on the KEKB design. As an preliminary test of the longitudinal kicker, a simple mode-feedback system which suppress a specific coupled-bunch mode were tested successfully. | ||
| MOPAN030 | Analysis of Transverse Beam Oscillation at Photon Factory | 221 |
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| FPGA based bunch by bunch feedback system to cure the transverse instabilities has been in operation stably since Oct. 2005. Specification and performance of the system will be introduced, transient measurement has been done to analyze the instability modes, which helps to understand the instability sources. Bunch by bunch beam oscillation, together with the digital turn-by-turn beam position measurement, injection oscillation damping is recorded and analyzed, transverse beam oscillation with and without the bunch by bunch feedback system will be shown in this paper. Precise tune measurement during this period will be presented. Turn by turn phase space monitor is also available with the data, from which the nonlinear beam dynamics can be revealed. | ||
| TUPMN044 | Status of R&D Efforts Toward the ERL-based Future Light Source in Japan | 1016 |
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| Energy Recovery Linacs (ERL), based on superconducting accelerators, are one of the most promising synchrotron light sources in future. The KEK and the JAEA, in collaboration with the ISSP, the UVSOR, and the SPring-8, are considering to realize together the ERL-based next-generation light source in Japan. To establish key technologies for that, active R&D efforts started. The R&D program includes the developments of ultra-low-emittance photocathode guns and of superconducting cavities, as well as experimental proofs of accelerator-physics issues at the ERL test facility, which will be built at the KEK campus. We are currently working on constructing a prototype photocathode gun, on designing superconducing cavities, and on designing a prototype ERL. The current plan of the prototype ERL comprises a full injector linac, one or two cryomodules for the main linac, and the beam return loop, which can be operated at beam energies from 60 to 160 MeV. The up-to-date R&D status will be reported. | ||
| TUPMN045 | PF-Ring and PF-AR Operational Status | 1019 |
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| In KEK, we have two synchrotron light sources which were constructed in the early 1980s. One is the Photon Factory storage ring (PF-ring) and the other is the Photon Factory advanced ring (PF-AR). The PF-ring is usually operated at 2.5 GeV and sometimes ramped up to 3.0 GeV to provide photons with the energy from VUV to hard X-ray region. The PF-AR is mostly operated in a single-bunch mode of 6.5 GeV to provide pulsed hard X-rays. Operational performances of them have been upgraded through several reinforcements. After the reconstruction of the PF-ring straight sections from March to September 2005, two short-gap undulators were newly installed. They allow us to produce higher brilliant hard X-rays even at the energy of 2.5 GeV. At present we are going to prepare a top-up operation for the PF-ring. In the PF-AR, new tandem undulators have been operated in one straight section since September 2006 to generate much stronger pulsed hard X-rays for the sub-ns resolved X-ray diffraction experiments. In this conference, we report operational status of the PF-ring and the PF-AR including other machine developments. | ||
| FRPMN039 | Measurement of Quadrupolar Tune Shifts After the Reconstruction of the Photon Factory Storage Ring | 4039 |
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The tune shift of transverse quadrupolar oscillations is a measure of a quadrupolar component of wakefields in the storage ring*. By measuring both dipolar and quadrupolar tune shifts, one can estimate the dipolar and the quadrupolar components of wakefields (exactly, kick factors) independently. We carried out such measurements before and after the upgrade of the Photon Factory storage ring. The results showed the change in the tune shifts which were caused by the replacement of many (about two-thirds of the ring) vacuum chambers.
* S. Sakanaka, T. Mitsuhashi, and T. Obina, Phys. Rev. ST Accel. Beams 8, 042801 (2005). |