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Journal Articles

Progress of the J-PARC cesiated rf-driven negative hydrogen ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Ikegami, Kiyoshi*; Takagi, Akira*; Namekawa, Yuya*; Ueno, Akira; Oguri, Hidetomo

AIP Conference Proceedings 2052, p.050002_1 - 050002_7, 2018/12

 Times Cited Count:2 Percentile:9.99

In the 2017/2018 campaign, the J-PARC cesiated rf-driven negative hydrogen (H$$^-$$) ion source producing H$$^-$$ beam with the beam current of 47 mA accomplished three long-term operations more than 2,000 hours without any serious issues. On the final day of this campaign, the ion source produced an H$$^-$$ beam current of 72 mA so that the linac commissioning group could demonstrate the beam current of 60 mA at the linac exit. We are also conducting an endurance test of a J-PARC-made antenna at a test bench. The antenna achieved the operation time approximately 1,400 hours.

Journal Articles

Present status of the J-PARC cesiated rf-driven H$$^-$$ ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Shibata, Takanori*; Nammo, Kesao*; Namekawa, Yuya*; Ueno, Akira; Oguri, Hidetomo

AIP Conference Proceedings 2011, p.050018_1 - 050018_3, 2018/09

 Times Cited Count:3 Percentile:4.6

Journal Articles

Operation status of the J-PARC H$$^{-}$$ ion source

Okoshi, Kiyonori; Shinto, Katsuhiro; Nammo, Kesao*; Shibata, Takanori*; Ikegami, Kiyoshi*; Takagi, Akira*; Ueno, Akira; Namekawa, Yuya*; Oguri, Hidetomo

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.889 - 892, 2018/08

In 2017-2018 campaign, three times of long-time operation more than 2,000 hours of the J-PARC rf-driven negative hydrogen (H$$^{-}$$) ion source producing H$$^{-}$$ beam with the beam current of 47 mA were successfully achieved without any serious problems. At the final day of this campaign, the ion source produced an H$$^{-}$$ beam with the current of 72 mA in order to demonstrate the beam current of 60 mA at the linac exit. We are also conducting an endurance test of a J-PARC-made antenna at a test bench. Approximately 1,400-hour operation with the antenna was successfully performed.

Journal Articles

A Failure investigation of the beam collimator system in the J-PARC 3 GeV rapid cycling synchrotron

Okabe, Kota; Yamamoto, Kazami; Kamiya, Junichiro; Takayanagi, Tomohiro; Yamamoto, Masanobu; Yoshimoto, Masahiro; Takeda, Osamu*; Horino, Koki*; Ueno, Tomoaki*; Yanagibashi, Toru*; et al.

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.853 - 857, 2017/12

The most important issue is to reduce the uncontrolled beam loss in the high intensity hadron accelerator such as J-PARC proton accelerators. The J-PARC 3 GeV Synchrotron (RCS) has a collimator system which narrows a high intensity beam in the RCS. After startup of RCS in 2007, the collimator system of the RCS worked well. However, in April 2016, vacuum leakage at the collimator system occurred during the maintenance operation. To investigate a cause of the failure, we took apart iron shields of the collimator reducing exposed dose of operators. As a result of inspection, we succeeded to identify the cause of the vacuum leakage failure. In this presentation, we report the failure investigation of the beam collimator system in the RCS.

Journal Articles

Improvements of vacuum system in J-PARC 3 GeV synchrotron

Kamiya, Junichiro; Hikichi, Yusuke*; Namekawa, Yuya*; Takeishi, Kenichi; Yanagibashi, Toru*; Kinsho, Michikazu; Yamamoto, Kazami

Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.3408 - 3411, 2017/06

The RCS vacuum system has been upgraded since the completion of its construction towards the objectives of both better vacuum quality and higher reliability of the components. For the better vacuum quality, (1) pressure of the injection beam line was improved to prevent the H$$^{-}$$ beam from converting to H$$^{0}$$; (2) leakage in the beam injection area due to the thermal expansion was eliminated by applying the adequate torque amount for the clamps; (3) new in-situ degassing method of the kicker magnet was developed. For the reliability increase of the components, (1) A considerable number of fluoroelastmer seal was exchanged to metal seal with the low spring constant bellows and the light clamps; (2) TMP controller for the long cable was developed to prevent the controller failure by the severe electrical noise; (3) A number of TMP were installed instead of ion pumps in the RF cavity section as an insurance for the case of pump trouble.

Journal Articles

A Non-destructive profile monitor using a gas sheet

Ogiwara, Norio; Hikichi, Yusuke; Namekawa, Yuya; Kamiya, Junichiro; Kinsho, Michikazu; Hatanaka, Kichiji*; Shima, Tatsushi*; Fukuda, Mitsuhiro*

Proceedings of 7th International Particle Accelerator Conference (IPAC '16) (Internet), p.2102 - 2104, 2016/06

Journal Articles

Operation status of the J-PARC ion source

Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Koizumi, Isao; Takagi, Akira*; Namekawa, Yuya*; Yamazaki, Saishun; Ueno, Akira

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1081 - 1083, 2013/08

no abstracts in English

Journal Articles

Development of a Cs-seeded RF-driven H$$^{-}$$ ion source for the J-PARC

Yamazaki, Saishun; Ueno, Akira; Namekawa, Yuya*; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Koizumi, Isao; Oguri, Hidetomo

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.260 - 264, 2013/08

A cesium (Cs) seeded RF-driven H$$^{-}$$ ion source using an internal-antenna developed at the SNS (Spallation Neutron Source) is under development for the J-PARC (Japan Proton Accelerator Research Complex). The axial magnetic field optimization by using an axial magnetic field compensation (AMFC) coil significantly enhances the H$$^{-}$$ ion beam by typically 10%. An H$$^{-}$$ ion beam with a flat top duty factor of 2.5% (1 ms $$times$$ 25 Hz) of 77 mA, whose about 90% (corresponding to about 70 mA) of emittance of each direction is within 1.5 $$pi$$mm$$cdot$$mrad, is successfully extracted. During a demonstration operation over 100-hours, an H$$^{-}$$ ion beam over 66 mA was successfully produced with a relatively low RF power of about 40 kW by seeding Cs for 4-minutes a day.

Journal Articles

Impedance measurement of an antenna with hydrogen plasma driven by 13.56 MHz-rf for J-PARC H$$^{-}$$ ion source

Ueno, Akira; Namekawa, Yuya; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Oguri, Hidetomo

AIP Conference Proceedings 1390, p.292 - 299, 2011/09

 Times Cited Count:1 Percentile:58.52

A Cs free H$$^{-}$$ ion source driven with a LaB$$_{6}$$ filament is being operated at the J-PARC. Although it satisfies the J-PARC first stage requirements of an H$$^{-}$$ ion beam current of 30 mA and a life-time of 500 hours, it was proven that the current was not increased by seeding Cs. In order to satisfy the second stage requirements of an H$$^{-}$$ ion beam current of 50 mA and a life-time of 2000 hours, the development of a 13.56 MHz-rf-driven H$$^{-}$$ ion source was started by using an antenna developed at the SNS. As the first step, the impedance of an antenna with hydrogen plasma was measured. For an rf-power of 1.25 kW or 7.45 kW, it was measured as 11.82+80.22j $$Omega$$ or 21.16+58.24j $$Omega$$, respectively, which has a high real-part and positive rf-power dependence unexpectedly. By using the measured impedance, the circuit to produce rf-plasma in the plasma chamber on the -50kV potential with a 13.56 MHz-rf on the ground potential was designed by LTSpice IV.

Journal Articles

Operation status of the J-PARC negative hydrogen ion source

Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Namekawa, Yuya; Ueno, Akira

AIP Conference Proceedings 1390, p.235 - 244, 2011/09

 Times Cited Count:0 Percentile:100

A cesium-free H$$^{-}$$ ion source driven with a LaB$$_{6}$$ filament is being operated for J-PARC for about 4 years. Although the ion source can produce the H$$^{-}$$ ion current of 36 mA, the maximum current is restricted to 16 mA for the stable operation of the RFQ linac which has serious discharge problem from September 2008. The beam run is performed during 1 month cycle, which consisted of a 4-5 weeks beam run and a few days down-period interval. At the recent beam run, approximately 700 h continuous operation was achieved, which is satisfied with the requirement of the ion source lifetime for the J-PARC first stage. At every runs, the beam interruption time due to the ion source failure is a few hours, which correspond to the ion source availability of 99%. The R&D work is being performed in parallel with the operation in order to enhance the further beam current by using an ion source test stand.

Journal Articles

Operation status of the J-PARC negative hydrogen ion source

Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Namekawa, Yuya; Ueno, Akira; Takagi, Akira*

Proceedings of 8th Annual Meeting of Particle Accelerator Society of Japan (Internet), 3 Pages, 2011/08

The availability of the ion source is directly related to the operation time of the J-PARC accelerator. To evaluate the lifetime of the present ion source, we tried to perform two months beam operation in RUN#36. As the result of the trial operation, 1270 h continuous operation was achieved at the beam current of 16 mA. In RUN#37, the ion source was operated at 25 mA for 217 h at first, then the beam current was decreased to 16 mA. After 1029 h operation, the filament of the ion source was cut off and the beam run was interrupted. By considering the consumption rate of the filament is depended on the beam current, these operation results show the lifetime of the ion source is approximately 1200 h. For another attempt to improve the ion source availability, we tried to decrease the required time for maintenance. By unitizing the replacement parts and keeping them under the vacuum condition until just before the installing, the maintenance time can be decreased from four to two days.

Journal Articles

Status of the J-PARC negative hydrogen ion source

Oguri, Hidetomo; Namekawa, Yuya; Okoshi, Kiyonori; Ueno, Akira; Ikegami, Kiyoshi*

Proceedings of 25th International Linear Accelerator Conference (LINAC 2010) (CD-ROM), p.1016 - 1018, 2010/09

A cesium-free H$$^{-}$$ ion source driven with a LaB$$_{6}$$ filament is being operated for J-PARC. As of June 2010, there have been 34 beam commissioning or supply runs. In these runs, the ion source has been successfully operated in two different modes such as low current mode of 5 mA and high current mode of 30 mA. According to the task of the run, one of the two modes was selected. However, the beam current has been restricted to less than 15 mA for the stable operation of the RFQ linac which has serious discharge problem from September 2008. The beam run is performed 1 month cycles, which consisted of a 4-5 weeks beam run and 4 days down-period interval. At the recent beam run, about 600 hours continuous operation was achieved, which is satisfied with the requirement of the ion source lifetime for the J-PARC first stage. At every runs, the beam stop time due to the ion source failure is about one hour, which correspond to the ion source availability of 99%.

Journal Articles

Operation status of the J-PARC negative hydrogen ion source

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.

Journal Articles

Experiment of optimal filament shape for the J-PARC H$$^{-}$$ ion source

Namekawa, Yuya; Ueno, Akira; Okoshi, Kiyonori; Oguri, Hidetomo; Ikegami, Kiyoshi*

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.484 - 487, 2010/08

The J-PARC H$$^{-}$$ ion source driven with a lanthanum hexaboride filament (LaB$$_{6}$$-fil.) is successfully producing a stable beam for each J-PARC operation cycle of about 500 hours. However, its maximum peak H$$^{-}$$ ion current of 36 mA does not satisfy the requirement of 60 mA for the J-PARC design beam power of 1 MW. In this paper, two results of the experiments to increase the current with a sufficient life-time are presented. That using a flat quintuple-hairpin LaB$$_{6}$$-fil. resulted in the lower current of 33 mA and the lower life-time of less than 230 hours. The deterioration seemed to be caused by the localized emission area due to too large magnetic field on it. On the other hand, that using two triple-hairpin tungsten filaments (W-fil.) connected in parallel with a short distance resulted in a life-time of 500 hours with a 15 kW arc power operation, which should produce an H$$^{-}$$ ion current of more than 60 mA if cesium was seeded.

Journal Articles

Cesium seeding experiment for J-PARC H$$^{-}$$ ion source

Namekawa, Yuya; Ueno, Akira; Okoshi, Kiyonori; Oguri, Hidetomo; Ikegami, Kiyoshi*

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.845 - 847, 2010/03

The J-PARC H$$^{-}$$ ion source succeeds in producing a beam current of 38 mA without seeding Cs. It satisfies the requirement of the J-PARC 1st stage in which a beam power will be 0.6 MW. However a beam current of more than 60 mA is necessary for the J-PARC 2nd stage in which a beam power will be 1 MW. Therefore, two R&D(research and development)'s are being carried out in order to increase the beam current. One is without seeding Cs and the other is with seeding Cs. In the latter R&D, a beam current of 70 mA is produced with a W-filament and an arc-power of 15 kW. The low arc-power, will be helpful for reducing the Cs consumption rate. The lower Cs consumption rate is necessary for the stabler operation against sparking in high voltage gaps. The practicability of the ion source with seeding Cs is examined by optimizing the filament material and shape, the Cs seeding system including the temperature control of each part of plasma chamber and the plasma confinement magnetic field.

Journal Articles

Operation status of the J-PARC H$$^{-}$$ ion source

Oguri, Hidetomo; Ueno, Akira; Ikegami, Kiyoshi*; Namekawa, Yuya; Okoshi, Kiyonori

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.842 - 844, 2010/03

A cesium-free H$$^{-}$$ ion source driven with a LaB$$_{6}$$ filament is being operated for J-PARC. The beam commissioning of J-PARC accelerators started in November 2006. As of June 2009, there have been 25 beam commissioning or supply runs. In these runs, the ion source has been successfully operated in two different modes. One is a low beam current mode, in which approximately 5 mA is produced. The other is a high beam current mode, in which approximately 30 mA is produced. According to the task of the run, one of the two modes was selected. Since the beam current can be maintained within a few percent errors by tuning the ion source parameter once a day, 24 hours beam operation with an ion source operator only in day time was started in April 2008. The total interruption time during the runs due to the ion source failure is approximately 50 hours as of June 2009. The availability of the ion source is calculated to be 99%. The interruptions were mainly caused by the insufficient lifetime of the filament. By a few modifications on the filament shape administered until August 2007, we succeeded in achieving the lifetime of 2,030 hours, which included 1,250 hours in the low beam current mode and 780 hours in the high beam current mode.

Journal Articles

A Survey of optimal filament shape in the J-PARC H$$^{-}$$ ion source

Ikegami, Kiyoshi*; Ueno, Akira; Oguri, Hidetomo; Namekawa, Yuya; Okoshi, Kiyonori

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.839 - 841, 2010/03

A cesium-free H$$^{-}$$ ion source driven with a LaB$$_{6}$$ filament is under operation at the Japan Proton Accelerator Research Complex (J-PARC). The ion source succeeded in producing the maximum beam current of 38 mA, which is satisfied with the requirement for the J-PARC initial stage of 36 mA. The operating beam current, however, is within 30-33 mA during the accelerator beam commissioning run because we restrict the maximum arc current to 300 A for a highly stable beam operation. In order to improve the arc power efficiency for the beam current and to examine the possibility to satisfy with the requirement for the J-PARC final goal, we started to survey about the optimal size and shape of the LaB$$_{6}$$ filament by using the H$$^{-}$$ ion source test stand. All the tests were carried out with the same condition such as the arc current (300A), the beam energy and the magnet configuration of the plasma chamber. The beam current of 35.2 mA was extracted using a double spiral LaB$$_{6}$$ filament with a diameter of 29.5 mm and length of 35.5 mm, which is the same dimension as the present J-PARC ion source. By using a smaller one with a diameter of 15 mm and length of 34 mm, the beam current was increased to 41.8 mA. Furthermore, it was increased to 43.4 mA by using a flat triple hairpin shape LaB$$_{6}$$ filament.

Journal Articles

Recent operation status of Japan Proton Accelerator Research Complex H$$^{-}$$ ion source

Oguri, Hidetomo; Ueno, Akira; Ikegami, Kiyoshi*; Namekawa, Yuya; Okoshi, Kiyonori

Review of Scientific Instruments, 81(2), p.02A715_1 - 02A715_3, 2010/02

 Times Cited Count:3 Percentile:79.42(Instruments & Instrumentation)

Journal Articles

A Survey of optimal filament shape in a Japan Proton Accelerator Research Complex H$$^{-}$$ ion source

Ikegami, Kiyoshi*; Ueno, Akira; Oguri, Hidetomo; Namekawa, Yuya; Okoshi, Kiyonori

Review of Scientific Instruments, 81(2), p.02A717_1 - 02A717_4, 2010/02

 Times Cited Count:3 Percentile:79.42(Instruments & Instrumentation)

Journal Articles

Development of an H$$^{-}$$ ion source for Japan Proton Accelerator Research Complex upgrade

Okoshi, Kiyonori; Namekawa, Yuya; Ueno, Akira; Oguri, Hidetomo; Ikegami, Kiyoshi*

Review of Scientific Instruments, 81(2), p.02A716_1 - 02A716_4, 2010/02

 Times Cited Count:6 Percentile:64.92(Instruments & Instrumentation)

36 (Records 1-20 displayed on this page)