972-MHz RF digital feedback control system for J-PARC linac

Kobayashi, Tetsuya; Michizono, Shinichiro*; Fang, Z.*; Matsumoto, Toshihiro*; Suzuki, Hiroyuki; Yamaguchi, Seiya*; Okada, Yoshihito*

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1068 - 1070, 2010/03

http://www.pasj.jp/web_publish/pasj6/papers/fpaca48.pdf

A 972-MHz RF system is being developed for 400-MeV upgrade of the J-PARC linac. The accelerating field stabilities should be less than 1% in amplitude and 1 in phase. The basic digital LLRF (Low-Level RF) concept is the same as that of the present 324-MHz system with a compact-PCI crate. The main alterations are RF and clock generator (RF&CLK), mixer and I/Q modulator (IQ&Mixer) and digital LLRF algorithm. Since the typical decay time of the new system is faster (because its operational frequency is higher than that of the present 324-MHz cavity), chopped beam compensation is essential. The performance study of the digital feedback system with a cavity simulator is summarized.

Confirmation tests for fabrication of low density MOX pellet for FBR

Murakami, Tatsutoshi; Suzuki, Kiichi; Hatanaka, Nobuhiro; Hanawa, Yukio; Shinozaki, Masaru; Murakami, Shinichi; Tobita, Yoshimasa; Kawasaki, Takeshi; Kobayashi, Yoshihito; Iimura, Naoto; et al.

JAEA-Technology 2008-017, 97 Pages, 2008/03

JAEA-Technology-2008-017.pdf:2.76MB

Low density MOX pellets for FBR "MONJU" have not been fabricated in Plutonium Fuel Fabricating Facility (PFPF) for these 9 years since completion of the first reload fuel for "MONJU" in 1995. In this period, about 60 % of machines in the pellet fabrication process of PFPF have been replaced with new ones, and fabrication of MOX pellets for "JOYO" has been continued using these machines. Concerning the feed MOX powders for "MONJU", the amount of decay heat has been increased with increase of accumulated Am-241 in this period. In addition, powder characteristic of recycled MOX powder which is one of feed powders, MH-MOX powder, UO powder and recycled MOX powder, was significantly changed by replacing former processing machine used for scrap recycling with improved one. Using MOX powder with increased decay heat and recycled MOX powder processed by new machine, a series of low density MOX pellet fabrication tests were conducted to confirm pellet fabrication conditions for current pellet fabrication machines from October in 2004 to August in 2006. As a conclusion, it was confirmed that low density MOX pellets could be fabricated using these feed powders and replaced machines by adjusting pellet fabrication conditions adequately. This report summarizes the results of a series of low density MOX pellet fabrication tests.

Oxidation behavior of -FeSi/Si nano-composite phases by IR absorption measurements

Morita, Kosuke*; Nakamura, Tatsuya*; Kobayashi, Hiroyuki*; Tatsumi, Takahide*; Narumi, Kazumasa; Maeda, Yoshihito

no journal, , 

no abstracts in English