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Suzuki, H.

Paper Title Page
TUPEA046 LLRF Controller Upgrade for the J-PARC 400 MeV LINAC 1434
 
  • Z. Fang, S. Anami, Y. Fukui, M. Kawamura, C. Kubota, S. Michizono, F. Naito, K. Nanmo, S. Yamaguchi
    KEK, Ibaraki
  • H. Asano, K. Hasegawa, T. Itou, T. Kobayashi, S. Shinozaki, N. Tsubota
    JAEA/J-PARC, Tokai-mura
  • E. Chishiro, H. Suzuki
    JAEA, Ibaraki-ken
 
 

The output energy of the J-PARC LINAC will be upgraded from 181 to 400 MeV in the next two years by adding high-beta acceleration sections. The upgrade of the FPGA-based digital LLRF controller for the 400 MeV LINAC will be presented in this paper. The new LLRF control system works for both the 324 MHz low-beta and 972 MHz high-beta sections. Many functions are added into the LLRF controller, such as 1) working for different RF frequencies, 2) gradually increasing the feedback gains in the feedback loop instead of fixed ones, 3) automatic chopped-beam compensation, 4) automatically switching the beam loading compensation in accordance with the different beam operation mode, 5) input rf-frequency tuning carried out by a FPGA to match the rf cavities during the rf start-up, 6) auto-tuning of the rf cavity tuner by detecting the phase curve of the rf cavity during the field decay instead of the phase difference between the cavity input and output signals.

 
TUPEA050 Dual-harmonic Phase Control in the J-PARC RCS 1443
 
  • F. Tamura, M. Nomura, A. Schnase, T. Shimada, H. Suzuki, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • K. Hara, C. Ohmori, M. Tada, M. Yoshii
    KEK/JAEA, Ibaraki-Ken
  • K. Hasegawa
    KEK, Ibaraki
 
 

The wide-band RF cavities in the J-PARC RCS are operated in the dual-harmonic operation, in which each single cavity is driven by a superposition of the fundamental and the second harmonic RF signals. By the dual-harmonic operation large amplitude second harmonic signals for the bunch shape manipulation are generated without extra cavities. The phase control of the second harmonic RF is a key for the bunch shape manipulation. The fundamental RF signal is controlled by the phase feedback loop to damp the dipole oscillation. The second harmonic is locked to the phase of the vector-sum phase of the fundamental RF signals. We present the system detail and the performance in the beam operation of the RCS.

 
TUPEA051 Application of Digital Narrow Band Noise to J-PARC Main Ring 1446
 
  • A. Schnase, K. Hasegawa, M. Nomura, T. Shimada, H. Suzuki, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • K. Hara, C. Ohmori, M. Tada, M. Yoshii
    KEK/JAEA, Ibaraki-Ken
  • T. Koseki, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
  • M. Tomizawa
    KEK, Ibaraki
 
 

Applying narrow band longitudinal noise to the beam in J-PARC Main Ring in flattop, while the acceleration voltage is off might help to counteract the effect of ripple on the slow extraction. For this purpose, a complex noise sequence output by DSP modulates a custom made DDS synthesizer to create single side spectra without carrier. The noise is calculated starting from a description in frequency domain. Then an algorithm creates narrow band spectra with optimized behavior in time domain. Frequency domain data is transformed to time domain, and the amplitude is smoothed. The smoothed data is transformed back to frequency domain, and the spectral shape is restored. This process repeats until the amplitude in time domain has converged, while the desired spectrum shape is preserved. Noise generated in this way can be tailored for different requirements. We show the signal properties, the hardware, and preliminary beam test results, when the noise is applied to the MR RF system.

 
TUPD010 Simulation of Longitudinal Emittance Control in J-PARC RCS 1940
 
  • M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, H. Suzuki, F. Tamura
    JAEA/J-PARC, Tokai-mura
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, M. Tada, A. Takagi, K. Takata, M. Yoshii
    KEK, Ibaraki
 
 

The Longitudinal emittance in J-PARC RCS should be controlled to accelerate a high intensity proton beam with minimal beam loss. In order to study and minimize the beam loss during acceleration, the optimized way to add the 2nd higher harmonic rf has been calculated by a particle tracking code. Furthermore, the bunch shape at RCS extraction should be controlled and optimized for the MR injection. For this purpose, the optimum RCS acceleration pattern has been calculated. We describe the simulation results and the comparison with the beam test.

 
THPEA019 Thermal Deformation of Magnetic Alloy Cores for J-PARC RCS RF Cavities 3717
 
  • T. Shimada
    KEK/JAEA, Ibaraki-Ken
  • K. Hara, K. Hasegawa, C. Ohmori, M. Tada, M. Yoshii
    KEK, Ibaraki
  • M. Nomura, A. Schnase, H. Suzuki, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

Several magnetic alloy cores of the RF cavities, which are installed in the 3 GeV rapid cycling synchrotron (RCS) of J-PARC have shown buckling after about two years operation. To find the reason, why the local deformation happened, we made a test setup. There we heat up MA cores in air by 500 kHz RF and measure the thermal deformation in order to collect information about the buckling process. The results obtained by comparing the expansion of cores made by different production methods are reported.

 
THPEA022 Condition of MA Cores in the RF Cavities of J-PARC Synchrotrons after Several Years of Operation 3723
 
  • M. Nomura, A. Schnase, T. Shimada, H. Suzuki, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • E. Ezura, K. Hara, C. Ohmori, M. Tada, M. Yoshii
    KEK/JAEA, Ibaraki-Ken
  • K. Hasegawa, K. Takata
    KEK, Ibaraki
 
 

We have been operating the RF cavities loaded with MA cores with a high field gradient of more than 20 kV/m since October 2007. We have been measuring the RF cavity impedance at the shutdown periods, and we detected the impedance reductions of RCS RF cavities on January and June 2009. Taking out the RF cavities from the beam line and opening them, we found that many of cores showed a buckling at the inner radius. Also detachment of the epoxy coating intended to prevent rusting was observed. We report the detail of condition of MA cores and the relation between the impedance reduction and core condition.

 
MOPEC065 Recent Status and Future Plan of J-PARC MA Loaded RF Systems 615
 
  • M. Yoshii, K. Hara, C. Ohmori, T. Shimada, H. Suzuki, M. Tada
    KEK/JAEA, Ibaraki-Ken
  • E. Ezura, K. Hasegawa, A. Takagi, K. Takata
    KEK, Ibaraki
  • M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

The Japan Proton Accelerator Complex includes the 3GeV rapid cycling synchrotron (RCS) and the 50GeV main ring synchrotron (MR). Both synchrotrons use the high field gradient magnetic alloy (MA) loaded cavities. In RCS, 11 RF systems have been fully operational since December 2008. The RCS RF systems are operated with dual-harmonic acceleration voltages. Beam acceleration and bunch shape manipulation are efficiently taking place. 120kW of the neutron user operation was started at the Material and Life science facilities in November 2009. In MR synchrotron, the 5th RF system were installed in August 2009, and therefore 5 RF systems are now in operation. Beam commissioning for delivering protons to the hadron facility and neutrino beam experimental facility are under way. The neutrino user experiment is intended to start January 2010. Proton beam operation with more than 100kW is required. The approaches to realizing high intensity operation and the MR upgrade plan will be presented.

 
THPEA016 Developments of Magnetic Alloy Cores with Higher Impedance for J-PARC Upgrade 3711
 
  • C. Ohmori, K. Hasegawa, A. Takagi
    KEK, Ibaraki
  • K. Hara, T. Shimada, H. Suzuki, M. Tada, M. Yoshii
    KEK/JAEA, Ibaraki-Ken
  • M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

Magnetic alloy cavities are successfully used for J-PARC synchrotrons. These cavities generate much higher RF voltage than ordinary ferrite cavities. For future upgrades of J-PARC facilities, a higher field gradient is necessary. It was found that the characteristics of magnetic alloy is improved by a new annealing scheme under magnetic field. A large production system using an old cyclotron magnet is under construction for the J-PARC upgrade. The status of core development will be reported.