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Maebara, Sunao; Moriyama, Shinichi; Saigusa, Mikio*; Sugimoto, Masayoshi
Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.1990 - 1992, 2006/06
International Fusion Materials Irradiation Facility (IFMIF) is an accelerator-based neutron irradiation facility employing the D-Li stripping reaction, to produce the neutron field similar to the D-T Fusion reactor (2 MW/m
, 20 dpa/year for Fe). The required beam current of 250 mA is realized by two beam lines of 125 mA, and the output energies at injector, RFQ and DTL were designed to be 0.1, 5 and 40 MeV, respectively. The operation frequency of 175 MHz was selected to accelerate the large current of 125 mA. After an intensive beam simulation, the RFQ with a total length of 12 m was designed to keep the minimum emittance growth with the RF injection power of 2.3 MW CW. For such a 12 m-long RFQ, two coupling plates are indispensable in order to suppress higher modes in a longitudinal direction at least. From beam dynamics point views, the transmission co-efficient has been evaluated by TOUTATIS code, and it is found that the transmission decay within 0.5% can be achieved by employing a gap width of less than 4 mm for a coupling plate design.
Wei, J.*; Okamoto, Hiromi*; Ochi, Shuta*; Yuri, Yosuke; Sessler, A. M.*; Machida, Shinji*
Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.2841 - 2843, 2006/00
Previously it was shown that by crystallizing each of the two counter-circulating beams, a much larger beam-beam tune shift can be tolerated during the beam-beam collisions; thus a higher luminosity can be reached for colliding beams. On the other hand, crystalline beams can only be formed at energies below the transition energy of the circular accelerators. In this paper, we investigate the formation of crystals in two types of high-transition-energy lattices, one realized by three-cell missing dipole modules and the other with negative bends. The latter type satisfies the maintenance condition for a crystalline beam.
Hayashi, Naoki; Lee, S.*; Toyama, Takeshi*
Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.1160 - 1162, 2006/00
The beam based alignment of the beam position monitor (BPM) becomes an important tool to reduce the closed orbit distortion (COD) in the recent accelerator. Normally, it requires the independent control of the quadrupole field. Changing the current of a quadrupole magnet, one would find the unperturbed position. However, the J-PARC Rapid-Cycling Synchrotron (RCS) has seven quadrupole families and only group of each family can be controlled simultaneously. There is neither separate power supplies nor auxiliary coil windings on each individual magnet. A similar alignment procedure is applicable for the coupled-controlled magnet system, but it becomes very complicated. For the simplest case, three magnets grouped together, four different beam orbits have to be measured at three different BPM locations. The method and some simulation results for J-PARC/RCS case will be presented in this report.
Sato, Kenichiro; Hayashi, Naoki; Lee, S.*; Toyama, Takeshi*
Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.1163 - 1165, 2006/00
A prototype of residual gas ionization profile monitor (IPM) for J-PARC RCS has been developed. It consists of electrodes producing electric field to collect ionized ions/electrons, MCP as a signal read-out device, an electron generator to evaluate the gain balance of MCP channels, and a wiggler type magnet producing guiding field. The monitor has been installed in KEK-PS main ring and has been examined using proton beam. At the conference, recent preliminary results of experiments are reported.
Sato, Susumu; Tomisawa, Tetsuo; Ao, Hiroyuki; Ueno, Akira; Akikawa, Hisashi*; Igarashi, Zenei*; Lee, S.*
Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.1151 - 1153, 2006/00
In the LINAC section of J-PARC, we have several type of sensors of monitor, i.e, Beam Position Monitor, Beam Profile Monitor, Beam Size Monitor, Current Monitor, Beam Phase Monitor, Beam Loss Monitor. Those sensors are being installed currently. The procedures, remarks during the installation, status are described in this paper. As an examle, the beam postion monitors are one of sensors which are taken cared intensively for their positioning on their housing quadrupole magnet, then our cares during their installation are described.
Irie, Yoshiro; Dooling, J.*; Horan, D.*; Kustom, R.*; Middendorf, M.*; Pile, G.*; Bayley, D.*; Cross, G.*; Gardner, I.*; Glover, M.*; et al.
Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.321 - 323, 2006/00
Wideband low-output-impedance RF system for the second harmonic cavity in the ISIS synchrotron has been developed by the collaboration between ANL (US), KEK (Japan) and RAL (UK). Low output impedance is realized by the feedback from plate to grid of the final triode amplifier, resulting in less than 30 ohms over a wide frequency range of 2.7 - 6.2 MHz. The vacuum tubes in the driver and final stages are both operated in class A. High power test was performed with a ferrite-loaded second harmonic cavity, where the bias current was swept at 50 Hz repetition rate. The maximum voltage of 12 kV peak per accelerating gap was obtained stably at earlier period of an acceleration cycle. A beam test with this system is planned at the ISIS synchrotron soon.
Takayanagi, Tomohiro; Ueno, Tomoaki; Irie, Yoshiro; Kinsho, Michikazu; Takeda, Osamu; Yamazaki, Yoshishige; Yoshimoto, Masahiro; Kamiya, Junichiro; Watanabe, Masao; Kuramochi, Masaya
Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.1762 - 1764, 2006/00
The shift bump magnet produces a fixed main bump orbit to merge the injection beam into the circulating beam. In order to control the injection beam for the short injection time (500 microseconds) with sufficient accuracy, the shift bump magnet needs a wide uniform magnetic field and the high speed exciting pattern of the high current. The magnetic field design and the structural analysis of the shift bump magnet have been performed using the three-dimensional electromagnetic analysis code and the mechanical analysis code, respectively. The magnetic field distributions were measured with a long search coil, thus giving a BL product over the magnet gap area. The temperature distributions at the various points of the magnet were measured by the thermocouples over 24 hours till they saturated. General trend of these measurements agrees well with calculations.
Tamura, Fumihiko; Schnase, A.; Nomura, Masahiro; Yamamoto, Masanobu; Yoshii, Masahito*; Anami, Shozo*; Ezura, Eiji*; Hara, Keigo*; Omori, Chihiro*; Takagi, Akira*
Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.1319 - 1321, 2006/00
In the J-PARC Rapid Cycling Synchrotron (RCS), the heavy beam loading effects due to the high intensity proton beam must be compensated for stable acceleration. The beam feedforward technique is used to compensate the beam loading in the RCS. We present the development of the feedforward system. We designed and built the full-digital system. Because of the low Q value of each accelerating cavity, the wake voltage consists of not only the accelerating harmonic component but also higher harmonics. Thus, the system is designed to compensate the beam loading at several harmonics. The vector components of the selected harmonic are detected from the beam signal picked up by a wall current monitor. The compensation RF signal is generated from the vector components with proper gain and phase in the latter part. The gain and phase are set individually for each harmonic and each cavity of the twelve cavities. We also present the preliminary test results of the newly developed modules.