| Paper |
Title |
Page |
| MOPCH118 |
Wideband Low-output-impedance RF System for the Second Harmonic Cavity in the ISIS Synchrotron
|
321 |
| |
- Y. Irie
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- D. Bayley, G.M. Cross, I.S.K. Gardner, M.G. Glover, D. Jenkins, A. Morris, A. Seville, S.P. Stoneham, J.W.G. Thomason, T. Western
CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
- J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf, G. Pile
ANL, Argonne, Illinois
- S. Fukumoto, M. Muto, T. Oki, A. Takagi, S. Takano
KEK, Ibaraki
|
|
| |
Wideband low-output-impedance RF system for the second harmonic cavity in the ISIS synchrotron has been developed by the collaboration between Argonne National Laboratory, US, KEK, Japan and Rutherford Appleton Laboratory, UK. Low output impedance is realized by the feedback from plate output to grid input of the final triode amplifier, resulting in less than 30 ohms over the frequency range of 2.7 - 6.2 MHz which is required for the second harmonic cavity. The vacuum tubes in the driver and final stages are both operated in class A, and a grid bias switching system is used on each tube to avoid unnecessary plate dissipations during a non-acceleration cycle. 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 12kV 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 in order to investigate how the low impedance system works under heavy beam loading conditions, and is capable of mitigating the space charge detuning at the RF trapping stage.
|
|
| TUPCH128 |
New Cutting Scheme of Magnetic Alloy Cores for J-PARC Synchrotrons
|
1313 |
| |
- C. Ohmori, S. Anami, E. Ezura, Y. Funahashi, K. Hara, K. Hasegawa, A. Takagi, M. Toda, K. Ueno, M. Yoshii
KEK, Ibaraki
- Y. Morita, T. Yoshioka
ICEPP, Tokyo
- M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
|
|
| |
A new cutting method using a grindstone was developed to manufacture the magnetic alloy cores. The problem of local temperature rise around the cut surfaces was solved. Long-term high-power tests have been performed for both J-PARC RCS and MR RF systems. Mechanism of local heating, new cutting scheme, and manufacturing method are presented.
|
|
| TUPCH130 |
Development of the Feed-forward System for Beam Loading Compensation in the J-PARC RCS
|
1319 |
| |
- F. Tamura, M. Nomura, A. Schnase, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Yoshii
KEK, Ibaraki
|
|
| |
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 with modern FPGAs to realize high accuracy, stability and predictability of the compensation. 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 system has two parts. In the first part, 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.
|
|
| TUPCH131 |
High Power Test of MA Cavity for J-PARC RCS
|
1322 |
| |
- M. Yamamoto, M. Nomura, A. Schnase, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
KEK, Ibaraki
- K. Hasegawa
JAEA, Ibaraki-ken
|
|
| |
We have been constructing the RF system for the J-PARC RCS. Almost all of the power supplies and the tube amplifiers have been constructed, and the cavities are under construction. All of them are tested at the experimental hall before installing into the J-PARC RCS building. We test the hybrid cavity scheme to realize the optimum cavity Q-value. The results of the test are described.
|
|
| TUPCH193 |
Low Level RF Control System Modules for J-PARC RCS
|
1465 |
| |
- A. Schnase, M. Nomura, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Yoshii
KEK, Ibaraki
|
|
| |
After completing the design phase, the VME modules for the Low Level RF Control (LLRF) of the Rapid Cycling Synchrotron of J-PARC are now in the production and debugging phase. First all modules are tested for basic functionality, for example dual harmonic signal generation. Then sets of modules are connected together to check higher-level functions and feedback. Finally, the LLRF modules are interfaced to high voltage components like amplifiers and cavities. We present the results of these tests, the test methods and test functions on several levels. This way we simulate beam operation working conditions and gain experience in controlling all parameters.
|
|
| TUPLS028 |
An Irradiation System for Carbon Stripper Foils with 750 keV H- Beams
|
1550 |
| |
- A. Takagi, Y. Arakida, Z. Igarashi, K.I. Ikegami, C. Kubota, I. Sugai, Y. Takeda
KEK, Ibaraki
- S. Dairaku, N. Saito, A. Sato, K. Senzaki
Kyoto University, Kyoto
- Y. Irie
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
|
|
| |
Carbon stripper foils of around 300 ug/cm2 will be used as a stripping of H-ion beam of the 3 GeV Rapid Cycling Synchrotron in the J-PARC. The foil should have a long lifetime with mechanically strong against high temperature of 1800K due to high-energy deposition by high intensity H-ion and circulating bunched proton beam irradiations. For this purpose, we have installed a new irradiation system using high intensity pulsed and dc H-beams of the KEK 750keV Cocksfoot-Walton accelerator. By adjusting the peak intensity and the pulse length of the hydrogen beams appropriately, the energy deposition becomes equivalent to that exerted by the incoming H- and the circulating beams at the injection process of the RCS. The new irradiation system and some preliminary results of the carbon stripper foil will be reported.
|
|
| TUPLS076 |
Beam Extraction of 150 MeV FFAG
|
1672 |
| |
- M. Aiba, Y. Mori, H. Nakayama, K. Okabe, Y. Sakamoto, A. Takagi
KEK, Ibaraki
- R. Taki
GUAS/AS, Ibaraki
- Y. Yonemura
Kyushu University, Fukuoka
|
|
| |
A beam extraction from FFAG accelerator was performed for the first time at KEK 150MeV proton FFAG synchrotron. The purpose of 150MeV FFAG project is to establish a working prototype for various applications. The beam extraction is thus one of important goals. The extraction is based on fast extraction methode using kicker and pulse septum working at 100Hz. A rapid cycling is also our focus to take advantages of FFAG accelerator. Beam extraction experiment was successful under 100Hz operating. The details of experiment will be presented in this paper.
|
|
| TUPLS108 |
Realization of Thick Hybrid Type Carbon Stripper Foils with High Durability at 1800K for RCS of J-PARC
|
1753 |
| |
- I. Sugai, K. Hara, H. Kawakami, M. Oyaizu, A. Takagi, Y. Takeda
KEK, Ibaraki
- T. Hattori, K.K. Kawasaki
RLNR, Tokyo
- Y. Irie, J. Kamiya, M. Kinsho
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
|
|
| |
The J-PARC requires thick carbon stripper foils (250-500 ug/cm2) to strip electrons from the H-beam supplied by the linac before injection into a 3 GeV Rapid Cycling Synchrotron. The 200 MeV H- beam from the linac has a pulse length of 0.5 ms with a repetition rate of 25 Hz and an average beam current of 335 uA. By much energy deposition of these high-intensity H- and circulating bunched beams, commercially available best stripper foils (CM) will break in a very short time and even a diamond foil will rupture at around 1800K by MW class accelerators. We have realized for first time the hybrid boron doped carbon stripper foils with long life time for J-PARC. The foils of 250-500 ug/cm2 were made by a controlled DC arc-discharge method. The lifetime was tested by using 3.2 MeV Ne+ DC beam of 2.5 uA and 750 keV H- DC beam of 500 uA, in which a significant amount of energy was deposited in the foils. The maximum lifetime was extremely long, 120- and 480-times than those of diamond and CM foils. The foils were also free from any shrinkage, and showed low thickness reduction rate even at high temperature of 1800K during long time irradiation of 90h.
|
|