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Journal Articles

Measurement of a time dependent spatial beam profile of an RF-driven H$$^-$$ ion source

Wada, Motoi*; Shinto, Katsuhiro; Shibata, Takanori*; Sasao, Mamiko*

Review of Scientific Instruments, 91(1), p.013330_1 - 013330_5, 2020/01

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

The ions are extracted from an ion source through a plasma sheath where a low frequency electromagnetic induction drives transport of charged particles including the target ions. High frequency alternating current commonly excites plasmas in sources for negative hydrogen (H$$^-$$) ions at a frequency in the MHz range. A high-speed beam current monitor system coupled to a narrow entrance slit enabled the investigation of the special distribution of the AC component intensity of the H$$^-$$ ion beam extracted from an ion source driven by a 2 MHz radio frequency (RF) power. The distribution showed a smaller oscillation of the beam at the center.

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

Observation of beam current fluctuation extracted from an RF-driven H$$^-$$ ion source

Shinto, Katsuhiro; Shibata, Takanori*; Miura, Akihiko; Miyao, Tomoaki*; Wada, Motoi*

AIP Conference Proceedings 2011, p.080016_1 - 080016_3, 2018/09

 Times Cited Count:3 Percentile:4.6

Journal Articles

Observation of plasma density oscillation with doubled value of RF frequency in J-PARC RF ion source

Shibata, Takanori*; Shinto, Katsuhiro; Takagi, Akira*; Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Nammo, Kesao*; Naito, Fujio*

AIP Conference Proceedings 2011, p.020008_1 - 020008_3, 2018/09

 Times Cited Count:4 Percentile:2.43

Journal Articles

Report of the 17th International Conference on Ion Sources (ICIS 2017)

Shinto, Katsuhiro

Kasokuki, 14(4), p.248 - 250, 2018/01

The 17th International Conference on Ion Sources (ICIS 2017) was held on 15th - 20th October 2017 at Geneva in Switzerland. This conference is held biennially. Most of scientists and engineers for ion sources in the world meet at the conference in order to share results of research and development.

Journal Articles

Effect due to RF discharge from a high intensity H$$^-$$ ion source upon the extracted beam

Shinto, Katsuhiro; Shibata, Takanori*; Wada, Motoi*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.648 - 650, 2017/12

In J-PARC, peak H$$^-$$ current of several tens mA is extracted from an ion source driven by a solid-state rf amplifier with the frequency of 2 MHz for production of a cesiated hydrogen plasma. In case of the rf-driven ion source for producing the high-intensity H$$^-$$ current, the plasma density in the source chamber is so high that the ion sheath around the beam extraction area can follow the rf oscillation. The H$$^-$$ beam current fluctuation as large as approximately 1 mA was observed at the average beam current of 44 mA measured by a Faraday cup installed downstream of the ion source. The beam exhibited some fluctuation to the transverse motion as well. To further clarify this high frequency oscillation of the beam extraction sheath, we propose a measurement system using a time-resolved and highly sensitive emittance monitor in order to observe the real-time beam fluctuation in the phase space.

Journal Articles

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

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

AIP Conference Proceedings 1869, p.030053_1 - 030053_7, 2017/08

 Times Cited Count:5 Percentile:3.46

A cesiated RF-driven negative hydrogen ion source was started to operate in September, 2014 in response to the need for upgrading J-PARC's linac beam current. The ion source mainly comprises a stainless-steel plasma chamber, a beam extractor, and a large vacuum chamber with two turbo molecular pumps of 1500 L/s for differential pumping. The ion source has been successfully providing the required beam current to the accelerator without any significant issues other than a single-incident antenna failure occurred in October, 2014. Continuous operation for approximately 1,000 h was achieved with a beam current and duty factor of 45 mA and 1.25 % (0.5 msec and 25 Hz), respectively. In this paper, we will present the some operation parameters and the beam stability through the long-term user operation.

Journal Articles

Improvement of high voltage rectifier of J-PARC klystron power supply

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.

JAEA Reports

Corroborative tests for Oarai Waste Reduction Treatment Facility using the in-can type high frequency induction heating method

Sakauchi, Hitoshi; Sato, Isamu*; Donomae, Yasushi; Kitamura, Ryoichi

JAEA-Technology 2015-059, 352 Pages, 2016/03

JAEA-Technology-2015-059.pdf:51.53MB

OWTF (Oarai Waste Reduction Treatment Facility) is constructed for volume reduction processing and stabilization treatment of $$alpha$$ solid waste, which was generated from hot facilities in Oarai Research and Develop Center of Japan Atomic Energy Agency, using in-can type high frequency induction heating by remote control. This report describes corroborative tests, in which incinerating and melting performance for OWTF is confirmed with a full-scale testing furnace. We have been carrying out the tests of incinerating and melting treatment with some kinds of simulated wastes, such as enclosure form of radioactive wastes, material and articles.

Journal Articles

Synthesis of hexagonal boron carbonitride without nitrogen void defects

Mannan, M. A.*; Baba, Yuji; Kida, Tetsuya*; Nagano, Masamitsu*; Noguchi, Hideyuki*

Materials Sciences and Applications, 6(5), p.353 - 359, 2015/05

The synthesis and structure of hexagonal boron carbonitride (h-BCN) film on polycrystalline diamond surface were reported. Polycrystalline diamond and/or diamond-like carbon were first fabricated on Si (100) and then it was used as substrate. The deposition was performed by radio frequency plasma enhanced chemical vapor deposition. In order to reduce the content of nitrogen void defects, the deposition was performed at the high temperature of 950$$^{circ}$$C under the working pressure of 2.6 Pa. The typical sample with atomic composition of B$$_{31}$$C$$_{37}$$N$$_{26}$$O$$_{6}$$ in the h-BCN lattice was characterized by X-ray photoelectron spectroscopy. The fine structure of the film was studied by near-edge X-ray absorption fine structure (NEXAFS) measurements. The B K-edge and N K-edge of NEXAFS spectra revealed that the synthesized h-BCN film has the ideal honeycomb-like BN$$_{3}$$ configuration without nitrogen void defects.

Journal Articles

Improvement of J-PARC klystron high voltage power supply

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.

Journal Articles

Present status of the high current prototype accelerator for IFMIF/EVEDA

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.

Journal Articles

Status of RF system for the J-PARC linac

Chishiro, Etsuji; Hori, Toshihiko*; Kobayashi, Tetsuya; Suzuki, Hiroyuki*; Suganuma, Kazuaki; Yamazaki, Masayoshi*; Anami, Shozo*; Fang, Z.*; Fukuda, Shigeki*; Fukui, Yuji*; et al.

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.236 - 238, 2005/07

no abstracts in English

Journal Articles

Low level RF control system for J-PARC RCS

Tamura, Fumihiko; Schnase, A.; Nomura, Masahiro; Yamamoto, Masanobu; Yoshii, Masahito*; Anami, Shozo*; Ezura, Eiji*; Hara, Keigo*; Omori, Chihiro*; Takagi, Akira*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.690 - 692, 2005/07

We describe the low level RF (LLRF) control system for the J-PARC Rapid Cycling Synchrotron (RCS). The LLRF system is required to be very stable and precise to achieve the high accelerating beam current. The system has the functions of the multi-harmonic RF generation, the feedback loops, the beam loading compensation, and other miscellaneous functions. The fully-digital LLRF system of the RCS is now under construction. The preliminary test results are also shown.

Journal Articles

Performance study of low-level RF analog feedback control system for J-PARC linac

Kobayashi, Tetsuya; Chishiro, Etsuji; Suzuki, Hiroyuki*; Anami, Shozo*; Yamaguchi, Seiya*; Michizono, Shinichiro*; Kawamura, Masato*; Fukui, Yuji*; Fang, Z.*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.320 - 322, 2005/07

Total System of 324MHz-Low Level RF Control for J-PARC Linac was produced and its performance study was done. In this system, in order to stabilize the Klystron output and to compensate the linearity of that, an analog feedback control system is adopted. The response function including phase characteristic (vector locus) of this feedback system was obtained by means of measurement. From this result the prospect for the transient analysis is discussed.

Journal Articles

Characterization of 50L-scale solidified products yielded by melting treatment of miscellaneous solid wastes and evaluation of radioisotope tracer distribution

Nakashio, Nobuyuki; Nakashima, Mikio; Hirabayashi, Takakuni*

Nippon Genshiryoku Gakkai Wabun Rombunshi, 3(3), p.279 - 287, 2004/09

Large-scale melting tests of simulated miscellaneous solid wastes were conducted to characterize solidified products (50L-drum size). Two heating modes were adopted in the tests: hybrid heating and induction heating modes. In the former, wastes were heated with both an induction furnace and a plasma torch, and in the latter, an electrically-conductive crucible was used with the induction furnace. Visual observation, chemical analysis and radioactivity measurements were conducted to the solidified products. It was found that the radioisotope distribution of solidified products was almost homogeneous. There was no remarkable deterioration in the solidified products subsequent to the leaching test.

Journal Articles

Improvement of RF low-level controller for JAERI ERL-FEL

Nagai, Ryoji; Sawamura, Masaru; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Nishimori, Nobuyuki; Nishitani, Tomohiro; Minehara, Eisuke

Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.293 - 295, 2004/08

no abstracts in English

Journal Articles

RF and timing reference distribution system for J-PARC linac

Kobayashi, Tetsuya; Chishiro, Etsuji; Anami, Shozo*; Yamaguchi, Seiya*; Michizono, Shinichiro*

Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.320 - 322, 2004/08

J-PARC (Japan Proton Accelerator Complex) linac, which is 300 m long, consists of 324 MHz accelerating section of the upstream and 972 MHz section (as future plan) of the downstream. In the klystron gallery, totally about 60 RF source control stations will stand for the klystrons and solid-state amplifiers. The error of the accelerating field must be within $$pm$$ 1 degree in phase and $$pm$$ 1% in amplitude. Thus, the high phase stability is required to the RF reference for all of the low-level RF control systems and the beam monitor systems. This paper presents a final design and the summary of the performance evaluation of the RF reference distribution system including the timing control signal distribution for this linac.

Journal Articles

Characteristics of low level RF system for DTL1 beam commissioning of J-PARC linac

Kobayashi, Tetsuya; Suzuki, Hiroyuki*; Anami, Shozo*; Yamaguchi, Seiya*; Kawamura, Masato*; Fukui, Yuji*; Kadokura, Eiichi*; Kamikubota, Norihiko*; Takagi, Makoto*; Yoshida, Susumu*; et al.

Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.314 - 316, 2004/08

The beam study of the low-energy front of J-PARC linac has been in progress in the KEK site. Last year, DTL1 (the first tank of three DTL's) was installed in addition to RFQ and the Medium Energy Beam Transport line, and the beam commissioning up to 20MeV has been performed successfully. In this paper, the low level RF (LLRF) System for this beam test is summarized and the performance of the RF feed back control system and monitor system of the phase and amplitude of the accelerating fields (324 MHz) is presented. It was found that the feed back system for Bunchers is also necessary to stabilize and to compensate for the beam induced fields.

145 (Records 1-20 displayed on this page)