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Journal Articles

Dependence of charge-exchange efficiency on cooling water temperature of a beam transport line

Yamamoto, Kazami; Hatakeyama, Shuichiro; Saha, P. K.; Moriya, Katsuhiro; Okabe, Kota; Yoshimoto, Masahiro; Nakanoya, Takamitsu; Fujirai, Kosuke; Yamazaki, Yoshio; Suganuma, Kazuaki

EPJ Techniques and Instrumentation (Internet), 8(1), p.9_1 - 9_9, 2021/07

The 3 GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex supplies a high-intensity proton beam for neutron experiments. Various parameters are monitored to achieve a stable operation, and it was found that the oscillations of the charge-exchange efficiency and cooling water temperature were synchronized. We evaluated the orbit fluctuations at the injection point using a beam current of the injection dump, which is proportional to the number of particles that miss the foil and fail in the charge exchange, and profile of the injection beam. The total width of the fluctuations was approximately 0.072 mm. This value is negligible from the user operation viewpoint as our existing beam position monitors cannot detect such a small signal deviation. This displacement corresponds to a 1.63$$times$$10$$^{-5}$$ variation in the dipole magnetic field. Conversely, the magnetic field variation in the L3BT dipole magnet, which was estimated by the temperature change directly, is 4.08$$times$$10$$^{-5}$$. This result suggested that the change in the cooling water temperature is one of the major causes of the efficiency fluctuation.

Journal Articles

Results of 1-MW operation in J-PARC 3 GeV rapid cycling synchrotron

Yamamoto, Kazami; Yamamoto, Masanobu; Yamazaki, Yoshio; Nomura, Masahiro; Suganuma, Kazuaki; Fujirai, Kosuke; Kamiya, Junichiro; Hatakeyama, Shuichiro; Hotchi, Hideaki; Yoshimoto, Masahiro; et al.

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.209 - 213, 2020/09

The J-PARC 3GeV Rapid Cycling Synchrotron (RCS) is aiming to provide the proton beam of very high power for neutron experiments and the main ring synchrotron. We have continued the beam commissioning and the output power from RCS have been increasing. In recent years, just before the summer shutdown period, we have been trying continuous supply of 1-MW high-intensity beam, which is the design value, to a neutron target. First trial was 1-hour continuous operation in July 2018, and second trial was 10-hours continuous in July 2019. In both cases, we achieved almost stable operation. Furthermore, in June 2020, we tried to operate continuously for over 40 hours. But in this case, some trouble occurred and the operation was frequently suspended. Through these continuous operation trials, we have identified issues for stable operation of 1 MW. In this presentation, we will report the results of 1-MW continuous operation and issues obtained from these results.

Journal Articles

Investigation for tiny metal contamination of water cooling system in J-PARC Linac

Suganuma, Kazuaki; Hiroki, Fumio; Ito, Takashi; Yamazaki, Yoshio

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.846 - 848, 2019/07

In the past, water flow decreased at water cooling system in J-PARC Linac. Contamination get mixed in cooling water. The problem was resolved by changing the system of the circulation pumps and reducing the tiny metal in water cooling system. However, suppression of occurring tiny metal is unresolved. The tiny metal is the unique problem of accelerator. It is caused by heavy using oxygen free copper and phosphorus deoxidized copper. The two copper is used for the part of accelerator and purified water. The object of the report is investigation of tiny metal contamination of water cooling system in J-PARC Linac.

Journal Articles

Production of the cooling towers fan bearing unit at J-PARC RCS

Fujirai, Kosuke; Suganuma, Kazuaki; Yamazaki, Yoshio

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1162 - 1164, 2019/07

Cooling water equipment of J-PARC RCS is supplying heat source equipment of an electromagnet cooling water. The cooling water is cooled in a cooling tower established outdoors. I heard abnormal noise from the bearing unit of the cooling tower fan in April, 2015 I decided to observe the state of the bearing unit. As a result of observation, it has a wound peculiar to a bearing of the pulley side. I decided to check why a bearing of the pulley side was damaged. When a fan goes around, a bearing on the pulley side is pulled by the upper and lower movement and fan belt which occur to a crosswise direction. I guessed a peculiar bruise the pulley side was that these vibration and load were added, and to have stuck. A bearing is the structure with which grease can't be replaced by the grease shutting tightly type, and I can think a small bruise has spread by the thing detached because a thing detached by braking drove in the remaining state in the bearing. So I decided to consider the above mentioned problem, move up and down for stable driving of a gas cooler fan and produce vibration of a crosswise direction and the bearing unit able to endure the load and replenish grease periodically newly. I'll report on vibration parameter of the structure of the bearing unit produced newly and an early stage by this publication.

Journal Articles

Progress status of proof-of-principle demonstration of 400 MeV H$$^{-}$$ laser stripping at J-PARC 3-GeV RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Miura, Akihiko; Yoshimoto, Masahiro; Okabe, Kota; Suganuma, Kazuaki; Yamane, Isao*; Irie, Yoshiro*; Liu, Y.*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.806 - 810, 2018/08

Journal Articles

Present status of water cooling system at J-PARC linac 2018

Suganuma, Kazuaki; Hiroki, Fumio; Ito, Takashi; Yamazaki, Yoshio

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.309 - 311, 2018/08

It is the report to improve the problem of flow reduction in water cooling system resolved completely in summer, 2017. It is continued the phenomenon decreasing the flow (5,800 L/min) of circulating water cooling in DTL and SDTL about 3% per week. By the flow reduction, the entire operation of J-PARC and operation of the accelerator are stopped and low flow contact of flowmeter installed in cavities. The phenomenon is progressed about 9 years since we confirm it and drastic measures for it are aspired. In this report, the point of interest to solve this problem is written. Similarly, it is suggested that the point we should be careful when we use the water cooling system it is one of the utility of J-PARC accelerator. In last summer, the flow reduction is not occur completely as specification changes and replacement of the pumps. Thanks of that, the entire operation and operation of accelerator of J-PARC is operated safety.

Journal Articles

Consideration on grease supply cycle and vibration measurement of rotating equipment

Fujirai, Kosuke; Suganuma, Kazuaki; Yamazaki, Yoshio

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.816 - 818, 2018/08

In order to operate rotating equipment such as a cooling water pump, it is necessary to supply grease suitable for bearings of rotating equipment. The grease replenishment interval has a value recommended by the manufacturer depending on the operation time. However, an abnormal noise occurred earlier than the replenishment cycle. I thought that the current grease replenishment cycle is not suitable for maintenance and management of rotating equipment. Therefore, I tried to search for suitable grease replenishment interval using a vibration sensor installed in the cooling water pump. As a result, it was found that the replenishment interval of grease is too long according to the manufacturer recommended value and should be supplied before the vibration acceleration value increases.

Journal Articles

Development of laser system for a proof-of-principle experiment of laser stripping injection

Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Inoue, Shunsuke*; Sato, Atsushi*; Suganuma, Kazuaki; Yamane, Isao*; Kinsho, Michikazu; Irie, Yoshiro*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.811 - 815, 2018/08

The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme can realize high intensity proton beam but the uncontrolled beam losses occur by scattering at the foil. Additionally, the beam collision at the foil may cause the break itself. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. We newly propose and develop a laser stripping injection scheme. At the first step, we propose a proof-of-principle (POP) experiment of the scheme in J-PARC and develop a laser system. In this presentation, we will introduce the laser stripping injection scheme and describe an overview of a POP experiment. We will report a current status of the laser system.

Journal Articles

Laser storage ring with high power for realization of laser stripping injection

Harada, Hiroyuki; Yamane, Isao*; Saha, P. K.; Suganuma, Kazuaki; Kinsho, Michikazu; Irie, Yoshiro*; Kato, Shinichi

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.684 - 688, 2017/12

The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme can realize high intensity proton beam but the uncontrolled beam losses are caused by scattering between beams and the foil. Additionally, the collision may occur the foil beak. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. In the J-PARC 3GeV RCS, we newly propose and develop a laser stripping injection scheme. However, it is necessary that laser power is two order higher than latest laser one. To realize this big issue, we develop the laser storage ring, which can provide laser pulse of high repetition rate by recycling one. In this presentation, we will introduce the laser stripping injection scheme and describe the concept of the laser storage ring with high repetition rate and report the current status.

Journal Articles

Vibration analysis of water cooling towers' defective fan bearing units at J-PARC RCS

Fujirai, Kosuke; Suganuma, Kazuaki; Yamazaki, Yoshio

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.874 - 876, 2017/12

The J-PARC (Japan Proton Accelerator Research Complex) 3-GeV RCS (Rapid Cycling Synchrotron) has many devices such as Radio-Frequency components, electromagnets and power supplies. These devices use 17MW of electricity during operation, most of which is consumed as thermal energy. Therefore, cooling water equipment is indispensable for the operation of the accelerator and its stability affects the operation rate of the accelerator. Due to resent operation experience, the bearing unit of the cooling tower fan, which is also an important part of the cooling water equipment, broke down. This accident leads to the suspension of the J-PARC operation. In order to investigate the cause of the failure, we tried to measure vibration for the defective bearing and the bearing unit were cut and observed damaged surface. As a result of the vibration measurement, it was found that vibration frequency depends on the presence or absence of scratches on the bearing. We found surface of the outer ring had scratches called flaking.

Journal Articles

Present status of water cooling system at J-PARC LINAC 2017

Suganuma, Kazuaki; Hiroki, Fumio; Ito, Takashi; Yamazaki, Yoshio

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.871 - 873, 2017/12

J-PARC LINAC has a problem that the amount of the flowing water is reduced. It spends such time from alarm to the restoration that it is desirable to take measures. So we have to solve this problem. We tried to focus again on the related water level fluctuation in the storage tank of cooling water equipment and the flow rate fluctuation all of the cooling water that has observed in cooling water equipment named RI4 from RFQ to SDTL of the LINAC. At the same time, we check new information of the operating data. We have hypothesized about the cause of fluctuation of the whole flow rate. That can be deterioration of water quality and lacking of performance of circulation pumps. That can be deterioration of water quality and lacking of performance of circulation pumps.

Journal Articles

Present status of water cooling system at J-PARC linac

Suganuma, Kazuaki; Hiroki, Fumio; Ito, Takashi; Yamazaki, Yoshio

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.304 - 306, 2016/11

J-PARC LINAC has a problem that the amount of the flowing water is reduced. It spends such time from alarm to the restoration that it is desirable to take measures. So we have to solve this problem. We tried to focus again on the related water level fluctuation in the storage tank of cooling water equipment and the flow rate fluctuation all of the cooling water that has observed in cooling water equipment named RI4 from RFQ to SDTL of the LINAC. At the same time, we check new information of the operating data. We have hypothesized about the cause of fluctuation of the whole flow rate. That can be deterioration of water quality and lacking of performance of circulation pumps. That can be deterioration of water quality and lacking of performance of circulation pumps.

Journal Articles

Electric resistance measurement of silicon carbide resistors

Suganuma, Kazuaki; Shimoyama, Nobuyoshi*; Yonekyu, Naoyuki*; Taki, Yukina*; Kinsho, Michikazu

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.686 - 688, 2015/09

no abstracts in English

Journal Articles

Operating experience of kicker magnet system in the J-PARC 3GeV RCS

Suganuma, Kazuaki; Togashi, Tomohito; Watanabe, Masao; Kinsho, Michikazu

Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.678 - 680, 2014/07

Technical issues of the kicker magnet system in the J-PARC 3GeV RCS are presented based on the operating experience during four years. For the high voltage cables, many scratches on the polyethylene surface were observed at the edge parts, the surfaces were reinforced by a semi-conductive layer with high-dielectric materials. For all matching resisters, the values have been increased due to deterioration with age, and the counter measure is under reviewing. For Thyratron tubes, a stable operation was established, and the beam stop rate by false operation was drastically reduced from 13% to less than 0.5%.

Journal Articles

Initial test of thyratron CX2004X

Suganuma, Kazuaki; Togashi, Tomohito; Kinsho, Michikazu

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.870 - 872, 2014/06

We started the initial tests of thyratron CX2004X at the switching test stand of the J-PARC. Deuteron gauss of this model is about 2 times as much as CX1193C one, by employing two reservoir tanks. A log life time more than thyratron CX1193C could be expected.

Journal Articles

Reduction of outgassing from the ferrite cores in the kicker magnet of J-PARC 3-GeV rapid cycling synchrotron

Ogiwara, Norio; Suganuma, Kazuaki; Hikichi, Yusuke; Nishikawa, Masaaki; Yanagibashi, Toru; Kamiya, Junichiro; Kinsho, Michikazu

Journal of the Vacuum Society of Japan, 56(5), p.159 - 162, 2013/05

Journal Articles

Operation maintenance of the thyratron for the power supply of the extraction kicker magnet in the J-PARC 3GeV RCS

Togashi, Tomohito; Watanabe, Masao; Suganuma, Kazuaki; Takayanagi, Tomohiro; Ueno, Tomoaki; Tani, Norio; Watanabe, Yasuhiro; Kinsho, Michikazu

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.471 - 473, 2012/08

The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) uses 8 pulse kicker magnets for the beam extraction at a repetition rate of 25 Hz. Each kicker power supply has 2 thyratrons and thus they are 16 in total. An average life time of thyratrons even more than the J-PARC annual operation time of 5000 hours and a stable operation with a downtime of less than only 0.5% has already been achieved. The present maintenance procedures and statistics for the long term operation with thyratrons are reported in this paper.

Journal Articles

Operation and current status of injection, extraction, kicker magnet and the power supply for J-PARC 3 GeV RCS

Watanabe, Masao; Hayashi, Naoki; Shobuda, Yoshihiro; Suganuma, Kazuaki; Takayanagi, Tomohiro; Togashi, Tomohito; Toyama, Takeshi*

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3629 - 3631, 2012/05

Stable operation is required for RCS at J-PARC. In the kicker system at extraction section of RCS, there had been many troubles for unstable operation of the thyratrons switches of the power supply just after 25 pps operation started in February 2009. However, the operation was improved by handling thyratrons in appropriate manner in October 2010. After the grate earthquake on 11 March 2011, injection and extraction magnets, power supplies, cables and bus-duct were checked. The results of the measurements and the checks were all not in the problem. We have to reach extraction beam power of 1 MW in RCS in the near future. Kicker impedance is most severe among other impedance sources. The matching resistor and newly developed diodes are connected at the power supply to reduce the impedance. We confirmed that reduced voltages and stable operation of accelerator.

Journal Articles

Reduction of outgassing from the ferrite cores in the kicker magnet of J-PARC RCS

Ogiwara, Norio; Suganuma, Kazuaki; Hikichi, Yusuke; Nishikawa, Masaaki; Yanagibashi, Toru; Kamiya, Junichiro; Kinsho, Michikazu

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.487 - 489, 2012/05

Journal Articles

Development of an in-situ bake-out method for outgassing reduction of kicker ferrite cores

Kamiya, Junichiro; Ogiwara, Norio; Nishikawa, Masaaki; Hikichi, Yusuke; Yanagibashi, Toru; Suganuma, Kazuaki

Journal of the Vacuum Society of Japan, 55(4), p.156 - 159, 2012/04

It is usually difficult to reduce outgassing of a large structure inside a vacuum chamber by baking the whole chamber, which causes the large extension of the chamber and needs a lot of heater power. The solution is to rise the temperature of structure object without heating the vacuum chamber. This means to install heat source inside the chamber and increase the heat quantity to the object by inserting the heat shield between the object and the chamber. In the particle accelerator field, there are a lot of such requirements for reducing outgassing of structures inside vacuum chambers. One example is a kicker magnet, which is installed in a vacuum chamber and consists mainly of ferrite cores and aluminum electric plates. We applied the above method to the outgassing reduction of the kicker. In this article, we show outline of this in-situ bake-out method, the effects of the heat shield on the heat quantity and the result of the outgassing reduction.

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