| Paper |
Title |
Page |
| THP006 |
Performance of a Digital LLRF Field Control System for the J-PARC Linac
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574 |
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- S. Michizono, S. Anami, Z. Fang, S. Yamaguchi
KEK, Ibaraki
- T. Kobayashi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- H. Suzuki
JAEA, Ibaraki-ken
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Twenty high power klystrons are installed in the J-PARC linac. The requirements for the rf field stabilities are ±1% in amplitude and ±1 deg. in phase during a 500 us flat-top. In order to satisfy these requirements, we adopt the digital feedback and feed-forward system with FPGAs and a commercial DSP board. The FPGAs (Virtex-II 2000) enable a fast PI control for a vector sum of two cavity fields. The measured stability during rf pulse was ±0.15% in amplitude and ±0.15 deg in phase. The tuner control was successively operated by a way of the DSP board by measuring the phase difference between the cavity input wave and the cavity field. Beam loading effects were emulated using a beam-loading test box. By proper feed-forward, the rf stability was less than ±0.3% and ±.15 deg.
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| THP009 |
Performance of RF Reference Distribution System for the J-PARC Linac
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583 |
| |
- T. Kobayashi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Anami, S. Michizono, S. Yamaguchi
KEK, Ibaraki
- E. Chishiro
JAEA, Ibaraki-ken
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Installation of the J-PARC linac machines (Phase I) has been almost completed and the beam commissioning will be started in December this year. The error of the accelerating field must be within ±1 degree in phase and ±1% in amplitude. Thus, high phase stability is required as an RF reference. Our objective concerning the phase stability of the reference aims at less than ±0.3 degrees. Last year the installation of the RF reference distribution system was completed. The reference signal is optically distributed to all of the low-level RF control systems by using E/O, O/E, Optical Amplifier and Optical Couplers and so on. The performance of this system was evaluated. The phase stability of ±0.06 degrees was obtained.
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