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Ishizaka, Tomohisa; Agematsu, Takashi; Yuri, Yosuke; Yuyama, Takahiro; Ishibori, Ikuo; Okumura, Susumu
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.642 - 644, 2010/08
no abstracts in English
Yoshida, Kenichi; Nara, Takayuki; Ishibori, Ikuo; Kurashima, Satoshi; Yuyama, Takahiro; Ishizaka, Tomohisa; Agematsu, Takashi; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; et al.
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.23 - 26, 2010/08
no abstracts in English
Nagai, Ryoji; Nishimori, Nobuyuki; Hajima, Ryoichi; Muto, Toshiya*; Yamamoto, Masahiro*; Miyajima, Tsukasa*; Honda, Yosuke*; Iijima, Hokuto*; Kuriki, Masao*; Kuwahara, Makoto*; et al.
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.806 - 808, 2010/08
A 500-kV, 10-mA photocathode DC gun which is designed for next-generation light- sources based on energy-recovery linac has been developed in a collaboration effort of JAEA, KEK, Hiroshima University and Nagoya University. We have utilized a segmented cylindrical ceramic insulator and guard-ring electrodes to prevent any damage to the insulator from electrons emitted by the support-rod electrode. The 500-kV gun was successfully conditioned up to a voltage of 550 kV and a long-time holding test for 8 h was demonstrated at an acceleration voltage of 500 kV. The cathode electrode, anode electrode, and beam line apparatuses are now under fabrication and beam tests of the gun will be started soon.
Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Namekawa, Yuya; Ueno, Akira
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.829 - 831, 2010/08
The J-PARC ion source has succeeded in providing the required beam to the accelerator for approximately 3.5 years without any serious trouble. At the recent beam run, approximately 600 hours continuous operation was achieved. Although the ion source can produce a maximum beam current of 36 mA, the beam current has been restricted to less than 16 mA for the stable operation of the RFQ linac which has serious discharge problem. After each beam run, we perform the ion source maintenance to replace some elements for the plasma production such as a filament, a plasma chamber and so on. Approximately three days was necessary to accomplish the maintenance. In order to enhance the availability of the accelerator, reduction of the maintenance time is indispensable. At present, we succeed in cutting the maintenance time in half by using the filament pre-baking system. We will make another attempt to shorten the time by unitizing the replacement elements in the near future.
Miura, Akihiko; Kobayashi, Tetsuya; Hasegawa, Kazuo; Sako, Hiroyuki; Ikegami, Masanori*
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.939 - 941, 2010/08
MEBT-Chopper tuning procedure was proposed using a downstream wire scanner monitor and this has been employed for the beam commissioning of the J-PARC Linac. This paper introduces the results obtained by several tuning experiences and its tendencies. Finally, tolerance depending on the tank level of RFQ (Radio-Frequency Quadrupole Linac) is introduced.
Suganuma, Kazuaki; Watanabe, Masao; Takeda, Osamu; Kinsho, Michikazu
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.972 - 974, 2010/08
This is a report on the dielectric breakdown at connectors for high-voltage coaxial cables and countermeasures. In March 2010, dielectric breakdown occurred in the polyethylene insulation layer at connector. There were scratches on the surfaces of the polyethylene insulation layers of all cables. These scratches are considered due to electric discharge. A connector that can inhibit electric discharge was discussed. As a result, the concentration of electric fields can be prevented by covering the edges of a semiconductive layer with high-dielectric materials.
Kawase, Masato; Yoshimoto, Masahiro; Takeda, Osamu; Kinsho, Michikazu
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.1065 - 1067, 2010/08
no abstracts in English
Miyawaki, Nobumasa; Okumura, Susumu; Yuyama, Takahiro; Ishizaka, Tomohisa; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Ishibori, Ikuo; Yuri, Yosuke; Nara, Takayuki; et al.
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.975 - 978, 2010/08
The ratio of the beam changing time, which is the time for changing the operation condition of the cyclotron, to the whole operation time is large at the JAEA AVF cyclotron, since most irradiation time is short and frequent change of beams is required by users, mainly in materials science and biotechnology. In order to increase the efficiency of the use of the cyclotron, we are developing a technique for reducing the beam changing time, which is dominated by the start-up process of the magnetic field. A quick start-up process for the main magnetic field with a damping oscillation excitation allows to reduce the start-up time of the magnetic field.
Shimada, Taihei; Yamamoto, Masanobu; Nomura, Masahiro; Schnase, A.; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Toda, Makoto*; Suzuki, Hiromitsu; et al.
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.549 - 551, 2010/08
The beam pipes of the RF acceleration section in the J-PARC RCS have a large aperture (247 mm) in order to handle a high power proton beam of 1 MW with acceptable loss. When we disassemble and later reassemble the test cavity in between the high power test runs for the MA cores, it is quite hard work to take out, and reinstall the beam pipe. Therefore, instead of using an original beam pipe, risking that it becomes unusable for accelerator operation due to scratches or discharges, we developed a light weight dummy beam pipe and dedicated copper connection parts for the acceleration gaps, which are easy to take apart and to assemble. Accordingly, the copper parts, which are used to connect the acceleration gaps to the cavity tanks for the installed cavity systems were redesigned, so that the time required for assembly or disassembly is reduced. This is especially important, as the cavities in the accelerator tunnel are in a high radiation environment caused by high power RCS operation.
Sawamura, Masaru; Nagai, Ryoji; Nishimori, Nobuyuki; Hajima, Ryoichi; Hayakawa, Takehito; Shizuma, Toshiyuki
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.868 - 870, 2010/08
We propose a non-destructive assay system of nuclear materials using laser Compton scattering combined with the energy-recovery linac and laser. To construct this system in a building such as the nuclear reprocessing plant, it is important to make the accelerating cavity small. The spoke cavity has advantages over the elliptical cavity to use for our proposing system. The calculation to optimize the spoke cavity shape has been begun with the 3D electromagnetic simulation code MAFIA.
Ito, Takashi; Nammo, Kesao*
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.555 - 557, 2010/08
After summer maintenance of 2009, we had trouble of decrease in flow rate of cooling water for DTQ. Once the alarm of flow switch is ON during the beam operation, the beam operation is forced to stop more than two hours. We must avoid this situation because it is robed users of time to do experiment. We have investigated the cause of decrease in flow rate of cooling water and resolve this problem since last summer. In this paper, the cause and its measures of cooling water problem are reported.
J-PARC Center, Accelerator Division
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.8 - 11, 2010/08
The recent operation status of the J-PARC accelerators is reported in this paper. The discharge problem of the RFQ linac has been steadily recovered and the beam of 120 kW power has been supplied to the common use of MLF. Although the accelerators can deliver the beam power more than 300 kW to MLF, the operational power is limited from the point of stable operation of the target system for neutron production. MR started user runs by the fast extraction with tuning toward higher beam intensity. The hadron experimental facility has also been tuning the data acquisition system with adjusting beam lines using a slowly extracted beam.
Takayanagi, Tomohiro; Ueno, Tomoaki; Hayashi, Naoki; Yamazaki, Yoshio; Kinsho, Michikazu
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.584 - 586, 2010/08
In the bump system of the J-PARC (Japan Proton Accelerator Research Complex) 3-GeV RCS (Rapid Cycling Synchrotron), the performance improvement according to upgrade of the Linac (Linear Accelerator) to 400 MeV beam is planned. Both of the increase of the power supply capacity and the improvement of the setting accuracy of the output current are required. Moreover, the operating point that the vibration of the current ripple resonates with betatron tune was clarified. Therefore, the present level of the current ripple is necessary to decrease to half or less. The development of the pulse power supply system that solves the problems of the current ripple is required.
Kobayashi, Tetsuya; Ikegami, Masanori*
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.696 - 698, 2010/08
The function of the chopped beam loading compensation was implemented into the digital feedback/feed-forward control system of the J-PARC Linac LLRF system to stabilize the ACS cavity fields for the 400-MeV upgrade. The beam test of the chopped beam loading compensation was performed with the present 324-MHz cavity system. As the result, the chopped beam loading was successfully compensated and that this system is valid.
Kobayashi, Tetsuya
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.1082 - 1084, 2010/08
For 400-MeV upgrade of the J-PARC Linac. ACS (Annular Coupled Structure) cavities, which are driven by 972-MHz RF, will be installed. The ACS cavity has complicated structure. Its Q-value is very low and the operation frequency is tree times high in comparison with that of the SDTL cavity. So the stabilizing control of the ACS accelerating field will be more difficult than present RF system. Further more the chopped beam loading compensation is required. Especially, a debuncher will be located very far from the klystron, then the feedback loop delay will be about 1.5 us. This presentation will show the simulation results of the feedback control of the ACS cavity field including long loop delay and the effect of the chopped beam loading.
Sawabe, Yuki*; Suzuki, Takahiro; Ishiyama, Tatsuya; Fukuta, Shimpei; Kikuzawa, Nobuhiro
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.680 - 682, 2010/08
The output energy of the J-PARC proton LINAC will be upgraded from 181 to 400 MeV in the next two years by adding ACS modules. The present status of upgrade of the control system for the ACS section will be presented in this paper.
Kikuzawa, Nobuhiro; Suzuki, Takahiro; Ito, Yuichi; Miura, Akihiko; Fukuta, Shimpei; Ikegami, Masanori*; Sako, Hiroyuki; Kobayashi, Tetsuya; Suzuki, Hiroyuki; Hasegawa, Kazuo
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.677 - 679, 2010/08
To avoid heat damage and radioactivation by beam loss of the J-PARC accelerator, Machine Protection System (MPS) has been developed. Actually, high responsibility and high reliability have been achieved in J-PARC. Beam-stop method in addition to a way of RFQ OFF has been requested in order to avoid damage to the RFQ. Therefore, we have been developing a fast beam-stop system by using a RF chopper. The fast beam-stop system, including beam test, is described in this paper.
Ueno, Tomoaki; Takayanagi, Tomohiro; Togashi, Tomohito; Kinsho, Michikazu
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.965 - 968, 2010/08
The injection bump system of the 3-GeV RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Proton Accelerator Research Complex) consists of the pulse bending magnets for the injection bump orbit, which are four horizontal bending magnets (shift bump), four horizontal painting magnets (h-paint bump) and two vertical painting magnets (v-paint bump). The power supplies of the magnets are composed of multiple-connections of the IGBT (Insulated Gate Bipolar Transistor) assemblies. They excite the current waveform of the trapezoid pattern with the flat top for 500 
s and the flexible decay pattern. The exciting current and magnetic field were measured. The power supplies executed the good accuracy less than 1percent deviation to programmed pattern. Furthermore, the continuous long-term with stable has been performed. In this paper, the current status of the operation of the injection bump system is described.
Togashi, Tomohito; Watanabe, Masao; Suganuma, Kazuaki; Takayanagi, Tomohiro; Ueno, Tomoaki; Tani, Norio; Watanabe, Yasuhiro
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.579 - 583, 2010/08
The 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) has the pulse kicker power supply system which uses the thyratron switches for beam extraction. There were many troubles caused by unstable operation of thyratrons after beam commissioning started in January 2009. The, failure rate of the kicker power supply system was about 13%. To improve this status, we have been managed the operations of the thyratron in detail. As a result, the unstable operation has been improved and the failure rate has been achievement less than 0.5% (Run33) in April, 2010. In this paper, we report current status of the thyratron operation of the kicker power supply system.
Saeki, Riuji; Yoshimoto, Masahiro; Yamazaki, Yoshio; Takeda, Osamu; Kinsho, Michikazu
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.1025 - 1028, 2010/08
no abstracts in English
