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Journal Articles

Bayesian uncertainty evaluation of Charpy ductile-to-brittle transition temperature for reactor pressure vessel steels

Takamizawa, Hisashi; Nishiyama, Yutaka; Hirano, Takashi*

Proceedings of ASME 2020 Pressure Vessels and Piping Conference (PVP 2020) (Internet), 7 Pages, 2020/08

no abstracts in English

Journal Articles

Upgrade of the 3-MeV linac for testing of accelerator components at J-PARC

Kondo, Yasuhiro; Hirano, Koichiro; Ito, Takashi; Kikuzawa, Nobuhiro; Kitamura, Ryo; Morishita, Takatoshi; Oguri, Hidetomo; Okoshi, Kiyonori; Shinozaki, Shinichi; Shinto, Katsuhiro; et al.

Journal of Physics; Conference Series, 1350, p.012077_1 - 012077_7, 2019/12

 Times Cited Count:1 Percentile:52.4

We have upgraded a 3-MeV linac at J-PARC. The ion source is same as the J-PARC linac's, and the old 30-mA RFQ is replaced by a spare 50-mA RFQ, therefore, the beam energy is 3 MeV and the nominal beam current is 50 mA. The main purpose of this system is to test the spare RFQ, but also used for testing of various components required in order to keep the stable operation of the J-PARC accelerator. The accelerator has been already commissioned, and measurement programs have been started. In this paper, present status of this 3-MeV linac is presented.

Journal Articles

Status of 3 MeV beam scrapers for the J-PARC LINAC

Hirano, Koichiro; Sugimura, Takashi*; Kurihara, Toshikazu*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.324 - 328, 2018/08

We could use a 3 MeV beam scraper without a problem for five months when the scraper received to 1.3 times as high as a normal average beam current of the scraper in 1MW beam operation. The peak temperature on the scraper surface was 1800$$^{circ}$$C. Irradiation damage caused by the 3 MeV beam with particle number of 3E22 was 700 $$mu$$m depth. We study scraper materials which can withstand the current density higher than carbon composite used in the scraper because almost all beams can be irradiated to the scraper in 1 MW beam operation. Beam irradiation tests have been performed about graphene and tungsten as scraper materials with high heat conductivity. This paper describes beam irradiation test of the 3 MeV beam scraper and scraper materials.

Journal Articles

Negative hydrogen ion beam irradiation experiments of beam scrapers using the J-PARC 3 MeV-Linac

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$$^{circ}$$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 2900$$^{circ}$$C, 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.

Journal Articles

A 3 MeV linac for development of accelerator components at J-PARC

Kondo, Yasuhiro; Asano, Hiroyuki*; Chishiro, Etsuji; Hirano, Koichiro; Ishiyama, Tatsuya; Ito, Takashi; Kawane, Yusuke; Kikuzawa, Nobuhiro; Meigo, Shinichiro; Miura, Akihiko; et al.

Proceedings of 28th International Linear Accelerator Conference (LINAC 2016) (Internet), p.298 - 300, 2017/05

We have constructed a linac for development of various accelerator components at J-PARC. The ion source is same as the J-PARC linac's, and the RFQ is a used one in the J-PARC linac. The beam energy is 3 MeV and nominal beam current is 30 mA. The accelerator has been already commissioned, and the first development program, laser-charge-exchange experiment for the transmutation experimental facility, has been started. In this paper, present status of this 3-MeV linac is presented.

Journal Articles

Development of beam scrapers using a 3-Mev linac at J-PARC

Hirano, Koichiro; Asano, Hiroyuki; Ishiyama, Tatsuya; Ito, Takashi; Okoshi, Kiyonori; Oguri, Hidetomo; Kondo, Yasuhiro; Kawane, Yusuke; Kikuzawa, Nobuhiro; Sato, Yoshikatsu; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.310 - 313, 2016/11

We have used a beam scraper with the incident angle of 65deg to reduce the beam power deposition density in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC linac. The 65$$^{circ}$$ scraper was irradiated by the H$$^{-}$$ beam up to particle number of 1.47E22. We observed a lot of surface projections with several hundred micrometers high in the beam irradiation damage on the scraper by using the laser microscope. In order to study the limits of scrapers, we constructed a new 3 MeV linac at J-PARC. We will conduct the scraper irradiation test at the end of this year.

Journal Articles

Development of a vertical collimator at the mebt1 of J-PARC linac

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.

Journal Articles

Long distant microscope observation of radiation damage (blistering); Laser reflection microscope

Kurihara, Toshikazu*; Kobayashi, Hitoshi*; Sugimura, Takashi*; Hirano, Koichiro

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.814 - 816, 2016/11

A problem of irradiation damage is the one observed in each part of a component of particle accelerators; accelerating tubs, scrapers, monitors and neutron targets. In-situ observation by an actual proton accelerator is made our last target. We observed the radiation damage of the various materials used by particle accelerators. From the distant place the target which is in the high radiation area, we propose the method to get information from the catoptric light from the target using a laser as a light source. A principle of this observation method as well as generating process of blisterings and limitation of this method will be reported.

Journal Articles

Development of RF chopper system at J-PARC Linac, 2

Hirano, Koichiro; Kondo, Yasuhiro; Kawane, Yusuke; Shinozaki, Shinichi; Miura, Akihiko; Morishita, Takatoshi; Sawabe, Yuki; Sugimura, Takashi*; Naito, Fujio*; Fang, Z.*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.944 - 947, 2015/09

Two RF-deflecting cavities as a chopper and a beam scraper have been used in the MEBT1 between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We replaced with a newly fabricated RF chopper to decrease beam loss for the operation with 50 mA. We installed two new scrapers to absorb the higher power of the deflected beam by the RF chopper. This paper describes the RF chopper system and beam irradiation test results of the scraper.

Journal Articles

The Heat transfer analysis for a new large entry angled scraper for J-PARC Linac

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 $$^{circ}$$ is introduced as countermeasures. This paper reports the results of numeric simulations of the new scrapers and their installation schedule.

Journal Articles

Operating status of the ACS in the J-PARC linac

Nemoto, Yasuo; Tamura, Jun; Ito, Takashi; Morishita, Takatoshi; Hirano, Koichiro; Kondo, Yasuhiro; Oguri, Hidetomo; Sugimura, Takashi*; Nammo, Kesao*; Ao, Hiroyuki*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1101 - 1104, 2015/09

In J-PARC linac, ACS (Annular-ring Coupled Structure) has been operating for one and a half years. Through the long term operation, the ACS cavities have been well conditioned. Therefore, the vacuum pressure of the ACS was reduced to 1$$times$$10$$^{-7}$$Pa, which is much lower than the required value, and RF trip rate was steadily decreased. At present, the ACS continues to be stably operating without sacrificing the operating time of the J-PARC accelerator complex. The vacuum leaks caused by the generated crack in the aluminum chain clamps in the ACS beam line have happened five times in the past. To prevent the same situation from occurring, we replaced all the aluminum clamps to the stainless steel clamps. The residual radiation between each ACS cavity is considerably high. It is considered that the CT monitors, which have smaller aperture than that of other instruments in the beam line, contributes to the residual radiation. We are trying to reduce the residual radiation by enlarging the monitor's aperture and by replacing the unused monitors to the titanium ducts in this summer shutdown period.

Journal Articles

Beam test of a new radio frequency quadrupole linac for the Japan Proton Accelerator Research Complex

Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saishun; Hori, Toshihiko; Sawabe, Yuki; Chishiro, Etsuji; Fukuda, Shimpei; Hasegawa, Kazuo; Hirano, Koichiro; Kikuzawa, Nobuhiro; et al.

Physical Review Special Topics; Accelerators and Beams, 17(12), p.120101_1 - 120101_8, 2014/12

 Times Cited Count:6 Percentile:43.07(Physics, Nuclear)

We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.

Journal Articles

Present status of J-PARC linac

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

Journal Articles

Interlock system of beam line for beam current upgrade

Kawane, Yusuke*; Miura, Akihiko; Miyao, Tomoaki*; Hirano, Koichiro; Sugimura, Takashi*; Kato, Yuko; Sawabe, Yuki; Fukuda, Shimpei; Ouchi, Nobuo

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1288 - 1291, 2014/10

In the J-PARC Linac, because an upgrading of a beam current up to 50mA using an RF-driven ion source and a new RFQ Linac cavity is in progress, we have developed a new frontend equipments. In order to protect the scraper against 50 mA, we need to observe the temperature and to avoid the excess heat loading of the scraper surface and to count the irradiated beam particles. We also monitor the beam transmission between the upstream and downstream of the chopper cavity to check the chopping errors using the beam current monitors. We fabricated the interlock system for the temperature, irradiated particle numbers and beam transmission. And we tested them in the test stand with actual beam. This paper describes the interlock system and their test results.

Journal Articles

Development of RF chopper system at J-PARC Linac

Hirano, Koichiro; Ito, Takashi; Kondo, Yasuhiro; Shinozaki, Shinichi; Chishiro, Etsuji; Miura, Akihiko; Morishita, Takatoshi; Ikegami, Masanori*; Kubota, Chikashi*; Sugimura, Takashi*; et al.

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.858 - 861, 2014/06

Two RF-deflecting cavities as a chopper and a beam scraper have been used in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We plan to increase a peak beam current up to 50 mA by replacing an ion source and a RFQ after the summer shutdown in 2014. Beam loss occurs in the RF chopper for the 50 mA operation. Moreover, the beam scraper cannot fully stand the beam load with 50 mA, 0.5 ms, 3 MeV, and 25 Hz. We have studied the new RF chopper cavity by using HFSS code and the tandem scraper system with two scrapers.

Journal Articles

Development of a 3 MeV beam scraper for the J-PARC linac

Sugimura, Takashi*; Hirano, Koichiro; Nammo, Kesao*; Kurihara, Toshikazu*

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.862 - 866, 2014/06

By introducing a new ion source and a new RFQ, beam current will increase from 20 mA to 50 mA. According to an increase of the beam current, wasted beam that should not be accelerated in the following accelerator sections also increase. To stop wasted beam, there is a beam scraper in the MEBT region just after the RFQ at the beam energy of 3 MeV. An existing beam scraper is made of carbon composite material and it has a dent caused by merely small beam current of 20 mA in daily operation. A new scraper that endures upgraded beam current of 50 mA is the essential item for the beam power upgrade of J-PARC. Thermal simulations on several materials have been performed with the ANSYS code assuming the upgraded beam power. They revealed that maximum temperatures in a beam cycle are much higher than their melting points in some materials and consequently that lessening of heat load for a scraper by beam operation is an essential factor.

Journal Articles

Countermeasure of the multipactor at SDTL cavity in J-PARC Linac

Ito, Takashi; Hirano, Koichiro; Sugimura, Takashi*; Nammo, Kesao*

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.977 - 981, 2014/06

The Japan Proton Accelerator Research Complex (J-PARC) facilities were extensively damaged by the Great East Japan Earthquake on March 2011. We restarted the beam operation in December 2011 after the recovery works. However, a multipactor problem of SDTL5B cavity was occurred after the beam restoration. To solve this problem, we performed the analysis of the impurities on the inner surface of the cavity, adopted the countermeasure that is the improvement of the vacuum condition of the cavity and performed the conditioning of the cavity carefully in the summer maintenance period of 2012. By adopting the countermeasure and conditioning, the multipactor problem improved just after the beam restoration and the operation power had been decreased. We present the result of the countermeasures and the present operation status of the SDTL5 in this report.

Journal Articles

Beam loss occurred at DTL cavity in J-PARC linac

Miura, Akihiko; Miyao, Tomoaki*; Ito, Takashi; Hirano, Koichiro; Nammo, Kesao*; Maruta, Tomofumi; Tamura, Jun; Ikegami, Masanori*; Naito, Fujio*

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.653 - 655, 2013/08

The beam operation of J-PARC linac was suspended until December 2011 due to the damage by the Tohoku earthquake in March 2011. After resumed the operations, we measured the residual radiation along with the beam line during a short interval. Because the higher residual radiation was detected at the surface of drift tube linac (DTL) cavity by radiation survey, we installed the scintillation beam loss monitors (BLM) at the points where the higher radiation was detected to understand the cause of the radiation. Even the DTL section is low energy part of the linac, fine structure of the beam loss was observed by the scintillation BLM. And we measured the beam loss occurred at the DTL with the parameters of beam orbit and cavity settings. Also, the BLM is employed for the linac tuning. In this paper, the result of the radiation measurement and beam loss signals obtained by the scintillation BLMs are presented.

Journal Articles

Multipactor at SDTL cavity in J-PARC linac

Ito, Takashi; Hirano, Koichiro; Nammo, Kesao*

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1152 - 1156, 2013/08

After the recovery works from an earthquake, we started a high power conditioning of a DTL and an SDTL on November 2011 and restarted a beam acceleration on December 2011. The operation of the DTL and the SDTL was stable as with the operation before the earthquake without SDTL05B cavity. It was impossible to input an RF power into the SDTL05B in the about 300 kW to 400 kW range. Therefore the operating power was increased to 510 kW that is about 1.4 times those of before the earthquake. We have investigated the cause of this malfunction of SDTL05B, and a computer simulation showed that it is likely to be caused by a multipactor on the surface of the cavity wall. In this paper we present the result of the simulation, the various measurements and the countermeasure.

Journal Articles

Alternative reference temperature based on master curve approach in Japanese reactor pressure vessel steels

Hirota, Takatoshi*; Hirano, Takashi*; Onizawa, Kunio

Proceedings of 2013 ASME Pressure Vessels and Piping Conference (PVP 2013) (DVD-ROM), 7 Pages, 2013/07

Master Curve approach is the effective method to evaluate the fracture toughness of the ferritic steels accurately and statistically. The Japan Electric Association Code JEAC 4216-2011 was published based on the related standard ASTM E 1921-08 and the results of the investigation of the applicability of the Master Curve approach to Japanese reactor pressure vessel (RPV) steels. The reference temperature To can be determined according to this code in Japan. In this study, using the existing fracture toughness data of Japanese RPV steels, the method for determination of the alternative reference temperature RT$$_{To}$$ based on Master Curve reference temperature To was statistically examined, so that RT$$_{To}$$ has an equivalent safety margin to the conventional RT$$_{NDT}$$. Through the statistical treatment, the alternative reference temperature RT$$_{To}$$ was proposed as the following equation; RT$$_{To}$$ = To + C$$_{MC}$$ + 2$$sigma$$$$_{To}$$. This method is applicable to the Japan Electric Association Code JEAC 4206 as an option item.

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