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Shibata, Takanori*; Hirano, Koichiro; Hirane, Tatsuya*; Shinto, Katsuhiro; Hayashi, Naoki; Oguri, Hidetomo
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.417 - 421, 2021/10
In J-PARC linac, the operation of an rf-driven high-intensity H
ion source was initiated in 2014. For plasma ignition, the 2-MHz rf amplifier outputs the power of several tens kW. However the rf amplifier for the ion source and those for the accelerating cavities have not been synchronized. As a result, the wave hights in the beam waveforms were different in shot by shot. Therefore, we have developed an synchronization system between the rf system for the ion source and those for the cavity systems and succeeded the same wave hights in the waveforms.
Tamura, Jun; Kondo, Yasuhiro; Morishita, Takatoshi; Naito, Fujio*; Otani, Masashi*; Nemoto, Yasuo*
Journal of Physics; Conference Series, 1350, p.012080_1 - 012080_6, 2019/12
Times Cited Count：0 Percentile：0.06(Physics, Particles & Fields)In the Japan Proton Accelerator Research Complex (J-PARC) linac, negative hydrogen beams are accelerated from 190 MeV to 400 MeV by Annular-ring Coupled Structure (ACS) cavities. The RF input coupler of the ACS21 cavity, which is the twenty-first (the last) accelerating cavity in the order of beam acceleration, had a comparatively larger Voltage Standing Wave Ratio (VSWR) value than the other ACS cavities. Therefore, we designed and manufactured a rectangular waveguide which has a capacitive iris to adjust the coupling factor of the ACS21 cavity. By making use of the summer maintenance period in 2018, we installed the newly manufactured waveguide to the cavity. Consequently, the VSWR of the ACS21 was successfully decreased to the target value which leads to the critical coupling under the nominal accelerating condition with 50-mA peak beam current.
Hirano, Koichiro; Ishiyama, Tatsuya; Kurihara, Toshikazu*; Sugimura, Takashi*; Maruta, Tomofumi*
Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.847 - 852, 2017/12
Beam scrapers made of carbon composite have been used in the MEBT1 between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We have conducted the scraper irradiation test with the 3 MeV linac. The test piece of the scraper was irradiated by the H
beam up to particle number of 1.2E20. We measured the surface temperature of more than 3000
C using a high-speed radiation thermometer and observed the irradiation damage on the scraper by using the laser microscope. When the surface temperature exceeded 2900C, the ionic current of carbon and the irradiation damage on the surface of the test piece rapidly increased. This paper describes beam irradiation test results of the scraper.
Takei, Hayanori; Chishiro, Etsuji; Hirano, Koichiro; Kondo, Yasuhiro; Meigo, Shinichiro; Miura, Akihiko; Morishita, Takatoshi; Oguri, Hidetomo; Tsutsumi, Kazuyoshi
Proceedings of 5th International Beam Instrumentation Conference (IBIC 2016) (Internet), p.736 - 739, 2017/03
The Accelerator-driven System (ADS) is one of the candidates for transmuting long-lived nuclides, such as minor actinide (MA), produced by nuclear reactors. For efficient transmutation of the MA, a precise pre-diction of neutronics of ADS is required. In order to obtain the neutronics data for the ADS, the Japan Pro-ton Accelerator Research Complex (J-PARC) has a plan to build the Transmutation Physics Experimental Facility (TEF-P), in which a 400-MeV negative proton (H) beam will be delivered from the J-PARC linac. Since the TEF-P requires a stable proton beam with a power of less than 10W, a stable and meticulous beam extraction method is required to extract a small amount of the proton beam from the high power beam using 250kW. To fulfil this requirement, the Laser Charge Exchange (LCE) method has been developed. The LCE strips the electron of the H beam and neutral protons will separate at the bending magnet in the proton beam transport. To demonstrate the charge exchange of the H, a preliminary LCE experiment was conducted using a linac with energy of 3MeV in J-PARC. As a result of the experiment, a charge-exchanged H
beam with a power of about 5W equivalent was obtained under the J-PARC linac beam condition, and this value almost satisfied the power requirement of the proton beam for the TEF-P.
Chishiro, Etsuji; Sagawa, Ryu*; Toriyama, Minoru*
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.400 - 402, 2016/11
Klystron power supplies in the J-PARC have been generated high voltage DC power by chopping 12-phase AC voltage power by thyristors, and boosting the voltage up to 110 kV in step-up transformer and rectifying the voltage in high voltage rectifiers. Some of the high voltage transformers (HVTR), which consist of the step-up transformer and the high voltage rectifier and the reactor, were often broken in the running time of over 30,000 hours. This failure caused the long-term shut down of the J-PARC facility. The high voltage rectifier composed diodes and condensers by a series connection of 66 stages. Investigation of the failed rectifier shows that the capacitors ware applied the overvoltage because the flashover occurred on the ceramic surface. We investigated the mechanisms applying the overvoltage and took measure for the overvoltage to the rectifier. The HVTR with the improved rectifier has been operating for long term to assess the modification effect.
Futatsukawa, Kenta*; Kobayashi, Tetsuya*; Sato, Yoshikatsu; Shinozaki, Shinichi; Fang, Z.*; Fukui, Yuji*; Mizobata, Satoshi; Michizono, Shinichiro*
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.327 - 331, 2016/11
In the J-PARC linac, an intermediate-pulse with the comb-like structure is shaped by kicking an unwanted beam by the chopper cavity. Therefore, the cavities lying downstream of the RF-chopper have the beam loading with this beam shape. The present feedforward system which assumes the averaged beam current and not the comb-like beam was operated in the present LLRF, because the beam current in the linac was lower than the design value. However, it has been difficult that the required precision for the RF system is satisfied with increasing beam current. Thus, we performed the beam study of the beam loading compensation with the same shapes as the intermediate-pulses. The positive results for the cavities of SDTL and DTL with high Q values were obtained compared to the present system. On the other hand, when this compensation system was used in the case of ACS cavities, the neighbor modes were excited by the input RF. We have to improve the FF system for the operation against the real beam.
Hori, Toshihiko*; Shinozaki, Shinichi; Sato, Yoshikatsu; Mizobata, Satoshi; Fukui, Yuji*; Futatsukawa, Kenta*
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.429 - 432, 2016/11
The triode klystrons with a modulating anode have been used for the J-PARC linac. Recently, we exchanged four klystrons due to the frequent discharge at a modulating anode in the klystron tube. In order to understand the discharge mechanism and to estimate the time to replace the klystron, we need to monitor the long term performance of the klystron such as the degradation of a cathode emission current and the RF gain of the klystron tube and so on. Therefore, we started to develop the klystron perveance and gain monitor module (NIM Standard one). In this paper, we will present the design concept of the monitor module, and the first performance test result using the module prototype.
Sugimura, Takashi*; Maruta, Tomofumi*; Hirano, Koichiro
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.307 - 309, 2016/11
There is an upgrade plan of J-PARC (Japan Proton Accelerator Research Complex) Linac from currently operated beam parameters such as, beam current of 40 mA, beam pulse width of 0.5msec and repetition of 25 Hz, to 50 mA, 0.5msec and 50 Hz, respectively. To reduce beam loss during a beam acceleration is a must task to accelerate a high power beam. At J-PARC Linac, a beam from an ion source followed by RFQ (Radio Frequency Quadrupole) injected into a series of DTLs (Drift Tube Linac) through a MEBT1 (Medium Energy Beam Transport 1), where a beam matching and a beam pulse forming are carried out at the beam energy of 3 MeV. There are some locally activated spots in DTL area at the current beam power level so that some kind of mitigation measure is required. Beam simulation results show that the beam loss at the DTL area can be reduced if there is a pair of vertical beam collimators. This paper reports a design and fabrication status of new vertical collimators.
Naito, Fujio*; Anami, Shozo*; Ikegami, Kiyoshi*; Uota, Masahiko*; Ouchi, Toshikatsu*; Onishi, Takahiro*; Oba, Toshiyuki*; Obina, Takashi*; Kawamura, Masato*; Kumada, Hiroaki*; et al.
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1244 - 1246, 2016/11
The proton linac installed in the Ibaraki Neutron Medical Research Center is used for production of the intense neutron flux for the Boron Neutron Capture Therapy (BNCT). The linac consists of the 3-MeV RFQ and the 8-MeV DTL. Design average beam current is 10mA. Target is made of Beryllium. First neutron production from the Beryllium target was observed at the end of 2015 with the low intensity beam as a demonstration. After the observation of neutron production, a lot of improvement s was carried out in order to increase the proton beam intensity for the real beam commissioning. The beam commissioning has been started on May 2016. The status of the commissioning is summarized in this report.
Miyao, Tomoaki*; Maruta, Tomofumi*; Liu, Y.*; Miura, Akihiko
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1094 - 1096, 2016/11
no abstracts in English
Miura, Akihiko; Yoshimoto, Masahiro; Okabe, Kota; Yamane, Isao*
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1102 - 1106, 2016/11
no abstracts in English
Takei, Hayanori; Hirano, Koichiro; Tsutsumi, Kazuyoshi; Chishiro, Etsuji; Miura, Akihiko; Kondo, Yasuhiro; Morishita, Takatoshi; Oguri, Hidetomo; Meigo, Shinichiro
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.987 - 991, 2016/11
Accelerator-driven system (ADS) is one of candidates to transmute long-lived nuclides such as minor actinide (MA) produced at nuclear reactor. For efficient transmutation of the MA, precise prediction of neutronics of ADS is indispensable. In order to obtain the neutronics data for the ADS, J-PARC has a plan to build the Transmutation Physics Experimental Facility (TEF-P). Since the TEF-P requires stable power of the beam and will operate with thermal power less than 500 W and the proton beam power of 10 W so that a stable and meticulous beam extraction method is required to extract small amount of the beam from the high power LINAC beam with 250 kW. To fulfill requirement, Laser charge exchange method (LCE) has been developed for delivery of 400-MeV proton beam with 25Hz to the TEF-P. The LCE strips the electron of H beam and H
will separate at the bending magnet at the proton beam transport. The LCE device consists of YAG-laser with high power as 1.6 J/shot and 25 Hz and transport control system with high accuracy of the beam position. For the demonstration of the charge exchange of the H, the further LCE tests is conducted using H beam with energy of 3-MeV at RFQ test stand in J-PARC. In this paper, present status of LCE tests is presented.
Futatsukawa, Kenta*; Kobayashi, Tetsuya*; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; Hirano, Koichiro; Fang, Z.*; Fukui, Yuji*; Hori, Toshihiko; Michizono, Shinichiro*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1317 - 1320, 2015/09
In the J-PARC linac, an RF deflector installed in 3-MeV Medium Energy Beam Transport (MEBT1) is used to kick the unnecessary beam and the intermediate-pulse like a comb is created. The kicked beam leads to a scraper downstream the RF deflector and lose all kinetic energy. When the beam current increases to 50 mA of the design value, the heat load of a scraper to irradiate the kicked beam increases and its surface is predicted to be damaged. Therefore, we are preparing the tandem scrapers to reduce the damage. The half of the kicked beam leads to a scraper and the residual is to the other. The chopping operation is achieved by rotating the phase of the RF deflector in the periodic cycles by the LLRF system. We will introduce the phase rotation system and the test results.
Sugimura, Takashi*; Hirano, Koichiro
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.954 - 957, 2015/09
The beam power of 1MW is a design specification of J-PARC. Therefore the beam current upgrade to 50 mA in the injector linac is indispensable. The scrapers installed in the linac have been took waste beam out of RFQ since last summer. They consist of Carbon composite surface plates and Copper block with cooling-water channel. The deterioration of thermal conducting has been observed during daily operation. Thus, a newly designed scraper with a large entry angle of 67 is introduced as countermeasures. This paper reports the results of numeric simulations of the new scrapers and their installation schedule.
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Araki, Sakae*; Honda, Yosuke*; Kosuge, Atsushi*; Terunuma, Nobuhiro*; Urakawa, Junji*
Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.1607 - 1609, 2015/06
Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 deg., respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm
placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200 /s, 6.91 keV, and 81 eV, respectively.
Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10
no abstracts in English
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Urakawa, Junji*
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1328 - 1331, 2014/10
A high intensity 
-ray source from the laser Compton scattering (LCS) by an electron beam in an energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear materials. In order to demonstrate accelerator and laser technologies required for a LCS photon generation, a LCS photon source is under construction at the Compact ERL (cERL). The LCS photon source consists of a mode-locked fiber laser and a laser enhancement cavity. A beamline and an experimental hatch are also under construction. The commissioning of the LCS photon source will be started in February 2015 and LCS photon generation is scheduled in March 2015.
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Urakawa, Junji*
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.839 - 842, 2014/10
In order to demonstrate accelerator and laser technologies required for a laser Compton scattering (LCS) photon generation, a LCS photon source is under construction at the Compact ERL (cERL). We considered the flux monitors for the adjustment LCS photon source. A thin scintillator detector and a silicon drift detector are employed as flux monitors and are installed at the upstream part of the LCS beamline. The background signal level due to the bremsstrahlung of the electron beam was measured by a CsI(pure) scintillator. In the result of the measurement, the background signal is acceptable level for the flux monitors.
Chishiro, Etsuji; Kawamura, Masato*; Sagawa, Ryu*; Ogawa, Shinichi*
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1091 - 1093, 2014/10
In J-PARC linac, six units of high voltage power supplies for 324 MHz klystrons have operated since 2006, and those running time exceed 35,000 hours. In addition, six units of power supplies for the 972 MHz klystrons have been operation since 2013. In the power supply, various troubles occur under the operation. In some anode modulators, arc discharge in the transformer oil had occurred due to the deterioration of the auxiliary solid insulator. In three modules combining a step-up transformer and a rectifier, the high voltage diode was breakdown because an unexpected overvoltage was applied. And by improving the voltage dividing resistor of the module, high stability cathode voltage was achieved. In this report, we describe the trouble and the improvement that occurred in the equipment.
Okumura, Yoshikazu
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.194 - 198, 2014/10
International Fusion Materials Irradiation Facility (IFMIF) is one of the major facilities in fusion program to irradiate and characterize the fusion materials under intense neutron field. Under the framework of Broader Approach (BA) agreement between Japan and Euratom, Engineering Validation and Engineering Design Activities (EVEDA) launched in 2007 in Japan to validate the key technologies to realize IFMIF. The most critical technology to realize IFMIF is two set of linear accelerators each producing 125mA/CW deuterium ion beams up to 40MeV. The prototype accelerator being developed in EVEDA consists of an injector, a RFQ accelerator, and a superconducting linac, whose target is to produce 125mA/CW deuterium ion beams up to 9MeV. The injector has been delivered to International Fusion Energy Research Center (IFERC) in Rokkasho, Japan, where all the accelerator components will be assembled and operated to validate the accelerator technologies required for IFMIF.
