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Nishimori, Nobuyuki; Hajima, Ryoichi; Nagai, Ryoji; Sawamura, Masaru; Kikuzawa, Nobuhiro; Shizuma, Toshiyuki; Minehara, Eisuke
Proceedings of 8th European Particle Accelerator Conference (EPAC 2002), p.822 - 824, 2002/00
The energy recovery linac with superconducting accelerator was constructed in JAERI (Japan Atomic Energy Research Institute) FEL, and the commissioning started in December 2001. The electron beam is injected into the energy recovery system at 2 MeV, accelerated up to 17 MeV and damped after deceleration down to 2 MeV by the same accelerator. The bunch charge of the electron beam is 0.5 nC with micro-pulse repetition rate of 10 MHz. The energy recovery rate was estimated to be more than 95 % from an RF input power with and without energy recovery. In this paper, we show the present results of energy-recovery experiments.
Yamamoto, Masanobu; Tamura, Fumihiko; Ezura, Eiji*; Hashimoto, Yoshinori*; Mori, Yoshiharu*; Omori, Chihiro*; Schnase, A.*; Takagi, Akira*; Uesugi, Tomonori*; Yoshii, Masahito*
Proceedings of 8th European Particle Accelerator Conference (EPAC 2002), p.1073 - 1075, 2002/00
Longitudinal beam emittance should be controlled to alleviate space charge effects by rf manipulations at 3 GeV proton synchrotrons in JAERI-KEK Joint High Intensity Proton Accelerator Project. At injection, bunching factor of 0.4 will be achived by controlled longitudinal beam painting and multiplying 2nd higher harmonics. Furthermore, heavy beam loading is a severe problem, and it should be compensated by feedforward method for stable acceleration. About these themes, the scenario will be described with particle tracking simulations.
Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Schnase, A.*; Omori, Chihiro*; Uesugi, Tomonori*
Proceedings of 8th European Particle Accelerator Conference (EPAC 2002), p.2106 - 2108, 2002/00
We present the concept and the design of the high-speed digital RF feedforward systems for beam loading compensation in the synchrotrons of JAERI-KEK Joint Project (JKJ). JKJ synchrotrons are high intensity proton synchrotrons at the energy of 3 and 50 GeV, in which beam loading compensation systems are necessary. Beam loading compensation is to be realized by full-digital RF feedforward systems. We describe the implementation details of the feedforward systems. The system consists of a down-converter, digital filters, and an up-converter. We present two possible implementations of the filters; one uses ASIC filter chips and the other uses FPGA.
Tani, Norio; Kanazawa, Kenichiro; Shimada, Taihei; Suzuki, Hiromitsu; Watanabe, Yasuhiro; Adachi, Toshikazu*; Someya, Hirohiko*
Proceedings of 8th European Particle Accelerator Conference (EPAC 2002), p.2376 - 2378, 2002/00
The 3-GeV synchrotron proposed in the JAERI/KEK Joint Project is a rapid-cycling synchrotron (RCS), which accelerates a high-intensity proton beam from 400 MeV to 3 GeV at a repetition rate of 25 Hz. The 3-GeV synchrotron is used to produce pulsed spallation neutrons and muons. It also works as an injector for a 50-GeV synchrotron. Since the magnets for the 3-GeV synchrotron are required to have a large aperture in order to realize the large beam power of 1 MW, there is a large leakage field at an end part than a usual synchrotron magnet. In addition, 25-Hz ac field induces an eddy current in magnet components: e.g. a coil, magnet end plates and etc. We intend to use a stranded conductor as a coil conductor so that the eddy current induced in the coil can be reduced. On the other hand, the eddy current induced in the end plates is expected to be large. Therefore, it is important to investigate an effect of the large leakage field and the eddy current to the beam motion around the magnet end part. We have constructed a prototype dipole magnet and field measurement system for this purpose. This paper reports the results of the design and the preliminary test about this magnet.