RF reference distribution system for J-PARC linac

Kobayashi, Tetsuya; Chishiro, Etsuji; Anami, Shozo*; Yamaguchi, Seiya*; Michizono, Shinichiro*

For the J-PARC linac, the error in the accelerating field needs to be maintained within 1% in amplitude and 1 in phase. Thus, high phase stability is required for the RF reference distribution system. A highly stable and unique RF reference distribution system was developed and installed for the J-PARC linac. A RF reference signal is converted into an optical signal and amplified by an optical amplifier. Then it is distributed through optical fiber links to 60 low-level RF control systems comprising klystron driving systems. Phase stabilized optical fiber (PSOF) is employed in the optical transfer line. The phase stability of the distributed signal was evaluated, and a phase stability of the 0.2 was obtained; consequently the required system stability was achieved. The beam acceleration to a design energy of 181 MeV for the first phase was successfully performed in February 2007. Now the beam commissioning has been steadily continued.