Author: Yamamoto, M.
Paper Title Page
THPPR043 Applications of X-band 950 keV and 3.95 MeV Linac X-ray Source for On-site Inspection 4071
  • M. Uesaka, K. Demachi, K. Dobashi, T. Fujiwara, H.F. Jin, M. Jin, H. Zhu
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • Y. Hattori
    Hitachi Engineering & Services Co.,Ltd., Japan
  • J. Kusano, N. Nakamura, M. Yamamoto
    Accuthera Inc., Kawasaki, Kanagawa, Japan
  • I. Miura
    Mitsubishi Chemical Corporation, Japan
  • E. Tanabe
    AET, Kawasaki-City, Japan
  Our portable X-band (9.3GHz) 950KeV linac has been successfully upgraded. The problems of RF power oscillation, beam current oscillation and reduction and finally lack of X-ray intensity were solved by replacing the axial coupling cavities with the side-coupled ones. Designed X-ray dose rate of 0.05 Sv/min@1m is going to be achieved. X-ray source part with the local radiation shielding is connected by the flexible waveguide with the box of a 250 kW magnetron and a cooling unit. The total system consists of the three suit-case-size units, the last of which is one for the electric power supply. We have also developed a portable X-band (9.3GHz) 3.95MeV linac for on-site bridge inspection. The system consists of a 62kg X-ray source part without 80kg target collimator, a 62kg RF power source and other utility box of 116kg. Designed X-ray dose rate is 2 Sv/min@1m with 200pps repetition rate and we have achieved 0.5 Sv/min@1m with 50pps repetition rate. Demonstration of the measurement of wall thinning of metal pipes with thick thermal shielding by 950keV linac and degradation of reinforced concrete sample by 3.95MeV is under way. Updated measurement results will be presented.  
WEPPR008 Simulation of Controlled Longitudinal Emittance Blow-up in J-PARC RCS 2952
  • M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  In the J-PARC RCS, a high intensity beam is prepared for the MR. The longitudinal beam emittance at the RCS extraction should be optimized to avoid beam loss during and after MR injection. In order to match the longitudinal emittance shape between the RCS and the MR, it is desirable to enlarge the longitudinal emittance during the RCS acceleration. We have performed the particle tracking simulation for the controlled longitudinal emittance blow up in the RCS.  
THPPC005 Design of Magnetic Alloy Resonant System (MARS) Cavity for J-PARC MR 3278
  • C. Ohmori, K. Hara, K. Hasegawa, M. Toda, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  The Magnetic Alloy Resonant System (MARS) cavity is a new type of Magnetic Alloy (MA) cavity using an external energy storage system. It is proposed as a back-up system of the present J-PARC high-Q MA cavity using cut cores. MARS consists of un-cut core loaded wideband MA cavities combined with an energy storage system using high-impedance, FT3L, cut cores. The main cavities are water-cooled and already established at J-PARC RCS. The energy storage system will be relatively high-Q (>100) to be stable under heavy beam loading. It also has a higher impedance than the main cavity and is air-cooled. The design of this cavity system will be presented.  
THPPP082 RF Feedforward System for Beam Loading Compensation in the J-PARC MR 3924
  • F. Tamura, M. Nomura, A. Schnase, T. Shimada, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • K. Hara, K. Hasegawa, C. Ohmori, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • M. Toda
    KEK/JAEA, Ibaraki-Ken, Japan
  For acceleration of high intensity proton beams in the J-PARC MR, beam loading compensation is important. In the MA-loaded RF cavity in the MR, which has a Q-value in the order of 20, the wake voltage consists of the accelerating harmonic (h=9) and the neighbor harmonics (h=8, 10). We employ the RF feedforward method for the beam loading compensation, like in the J-PARC RCS, in which the impedance seen by the beam is greatly reduced by the feedforward. The full-digital feedforward system developed for the MR has a similar architecture to that of the RCS. The system compensates the beam loading of the important three harmonics (h=8, 9, 10). We present the structure of the RF feedforward system. Also, we report the preliminary results of the beam tests.  
THPPC006 Status of the J-PARC Ring RF Systems 3281
  • M. Yoshii, E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda
    KEK, Tokai, Ibaraki, Japan
  • M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  Due to the 11th march earthquakes, J-PARC was forced to stop operation. The restoration is following the schedule so that J-PARC is restarted in December. Before the earthquake, we had considerable success in the 400 kW equivalent proton beam in the RCS. Multi-harmonic RF feedforward was established, which contributes to the reduction of beam loss and stable acceleration in RCS. The MR synchrotron achieved stable 150 kW beam operation for the T2K experiment. This summer, we installed two new RF systems in MR. Eight RF systems in total allow a more stable beam acceleration and flexible bunch shape manipulation. Also, we prepare the RF feedforward to compensate beam loading in MR. To achieve a beam power in excess of 1 MW in MR, it is considered to double the MR repetition rate. We developed an annealing scheme for large magnetic alloy cores while inside a DC B-field that results in higher core impedance, and have succeeded in producing large FT3L cores in this summer. With such cores we can almost double the accelerating voltage without re-designing the existing RF sources. For the near future, we plan to replace the existing RF cavities with upgraded cavities using the FT3L cores.  
THPPP080 Beam Halo Reduction in the J-PARC 3-GeV RCS 3918
  • H. Hotchi, H. Harada, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • Y. Irie, T. Koseki, Y. Sato, M.J. Shirakata
    KEK, Ibaraki, Japan
  • K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  The J-PARC RCS (3-GeV rapid cycling synchrotron) has two functions as a proton driver to the MLF (Materials and life science facility) and an injector to the MR (50-GeV main ring synchrotron). One of important issues in the current RCS bam tuning is to suppress the beam halo formation, which is essential especially to reduce the beam loss at the MR. In this paper, we present beam study results on the formation mechanism and reduction of the beam halo in the RCS.  
THPPP081 Status of Injection Energy Upgrade for J-PARC RCS 3921
  • N. Hayashi, H. Harada, H. Hotchi, J. Kamiya, P.K. Saha, Y. Shobuda, T. Takayanagi, N. Tani, M. Watanabe, Y. Watanabe, K. Yamamoto, M. Yamamoto, Y. Yamazaki, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  The injection energy upgrade for J-PARC RCS is planed in 2013. This includes the power supplies upgrade of injection pulsed magnet system, suppression for leakage field, quadrupole correction magnets, reduction of kicker impedance effect and improvements of beam diagnostic instrumentation. The paper reports the present status.  
MOPPP035 Initial Emittance and Temporal Response Measurement for GaAs Based Photocathodes 640
  • S. Matsuba
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  • Y. Honda, T. Miyajima, T. Uchiyama, M. Yamamoto
    KEK, Ibaraki, Japan
  • X.G. Jin
    Institute for Advanced Research, Nagoya, Japan
  • Y. Takeda
    Nagoya University, Nagoya, Japan
  For future light source based on Energy Recovery Linac (ERL) is planned in KEK. For the ERL, an ultra low emittance and fast temporal response and high current electron source is needed. To achieve these requirements, a high voltage DC gun with a Negative Electron Affinity photo-cathode is under development. In this development, it is important to investigate the performance of photo-cathodes. We have constructed an ERL gun test stand to measure emittance and temporal profile. We use a solenoid scan technique for emittance measurements and a deflecting cavity technique for temporal profile measurements. In this presentation, we introduce KEK ERL gun test stand and beam test results.  
TUPPP016 Recent Development of PF Ring and PF-AR 1641
  • Y. Tanimoto, T. Aoto, S. Asaoka, K. Endo, K. Haga, K. Harada, T. Honda, Y. Honda, M. Izawa, Y. Kobayashi, A. Mishina, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, T. Ozaki, C.O. Pak, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, K. Satoh, M. Shimada, K. Shinoe, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, M. Yamamoto
    KEK, Ibaraki, Japan
  • H. Takaki
    ISSP/SRL, Chiba, Japan
  After the earthquake of March 11, two light sources of KEK, PF ring and PF-AR, have recovered the regular operation from October, 2011. We installed tandem variably-polarized undulators at PF ring in 2009. Recently, the orbit switching system has been completed with sufficient feed-forward orbit compensation at 10-Hz. PF ring is usually operated at 450 mA with a top-up injection using the pulsed sextupole magnet instead of the conventional kicker magnets. The transverse and longitudinal instabilities are suppressed by a digital feedback system using the iGp signal processor. In the longitudinal direction, we observed unstable quadrupole mode oscillation which could not be controlled by the feedback system. We had applied the phase modulation of the main RF cavity to stabilize the quadrupole oscillation before. Old-type RF-shielded gate valves damaged by the earthquake were removed from the ring during the summer maintenance. In the operation after autumn, the quadrupole oscillation can be cured by dividing the bunch train of partial-filling. Without the phase modulation, the effective brightness of SR beam has been improved especially at beam lines of finite dispersion function.