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Journal Articles

Progress of long-time operation and industrial use of negative ion source for particle accelerator

Oguri, Hidetomo

Purazuma, Kaku Yugo Gakkai-Shi, 95(7), p.340 - 344, 2019/07

no abstracts in English

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

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

Cesiated surface H$$^{-}$$ ion source; Optimization studies

Ueno, Akira

New Journal of Physics (Internet), 19(1), p.015004_1 - 015004_15, 2017/01

 Times Cited Count:8 Percentile:30.12(Physics, Multidisciplinary)

In order to satisfy the increasing intensity requirements of high-energy and high-intensity proton accelerators for an H$$_{-}$$ ion beam with small transverse normalized rms emittances of around 0.25 $$pi$$mm$$cdot$$mrad, diverse parameters possibly reducing the emittances were optimised. Such as the plasma electrode shape and temperature, the radio-frequency (RF) matching network for the igniter plasma, the filter-field strength and distribution, the strength of the axial magnetic field around the beam extraction hole, the cesiasion procedure and the cesium (Cs) density, impurity elements, and so on, were optimized with H$$_{-}$$ ion sources for the Japan Proton Accelerator Research Complex (J-PARC). By optimizing each parameter step by step, the J-PARC cesiated RF-driven H$$_{-}$$ ion source successfully produced the world brightest class beam with 95% beam transverse normalized rms emittances of 0.24 $$pi$$mm$$cdot$$mrad and an intensity of 66 mA.

Journal Articles

Status of the RF-driven H$$^{-}$$ ion source for J-PARC linac

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

Review of Scientific Instruments, 87(2), p.02B138_1 - 02B138_3, 2016/02

BB2015-0491.pdf:1.81MB

 Times Cited Count:3 Percentile:73.85(Instruments & Instrumentation)

For the upgrade of the Japan Proton Accelerator Research Complex (J-PARC) linac beam current, a cesiated RF-driven negative hydrogen ion source was installed in 2014 summer shutdown period, and started to operate on September 29, 2014. The ion source has been successfully operated with a beam current and a duty factor of 33 mA and 1.25% (0.5 ms and 25 Hz), respectively. The result of recent beam operation showed that the ion source is capable of continuous operation for approximately 1,100 h. The spark rate at the beam extractor was observed to be less than once a day, which is acceptable level for the user operation. Although the antenna failure occurred during the user operation on October 26, 2014, there were no further serious troubles since then. In this conference, we will present the some operation parameters and the beam stability of the RF-driven ion source through the long-term user operation.

Journal Articles

Numerical study of plasma generation process and internal antenna heat loadings in J-PARC RF negative ion source

Shibata, Takanori*; Nishida, Kenjiro*; Mochizuki, Shintaro*; Mattei, S.*; Lettry, J.*; Hatayama, Akiyoshi*; Ueno, Akira; Oguri, Hidetomo; Okoshi, Kiyonori; Ikegami, Kiyoshi*; et al.

Review of Scientific Instruments, 87(2), p.02B128_1 - 02B128_3, 2016/02

BB2015-1473.pdf:4.28MB

 Times Cited Count:3 Percentile:73.85(Instruments & Instrumentation)

A numerical model of plasma transport and electromagnetic field in the J-PARC RF ion source has been developed to understand relation between antenna coil heat loadings and plasma production/transport processes. From the calculation, the local plasma density increase is observed in the region close to the antenna coil. The magnetic field line with absolute magnetic flux density 30-120 Gauss results in the magnetization of electron which leads to high local ionization rate. The results suggest that modification of magnetic configuration can be made to reduce plasma heat flux onto the antenna.

JAEA Reports

Filament lifetime test of the negative ion source for the high intensity proton accelerator

Oguri, Hidetomo; Namekawa, Yuya*

JAERI-Tech 2004-053, 35 Pages, 2004/07

JAERI-Tech-2004-053.pdf:1.33MB

The high intensity proton accelerator facility project (J-PARC) aims to pursue frontier science in materials science, nuclear physics and nuclear technology, using an accelerator complex at the highest beam power in the world. An H$$^{-}$$ ion source for the project is required to produce a beam current of $$>$$60 mA and an emittance of $$<$$0.20 $$pi$$mm.mrad with a duty factor of 2.5 %. In addition, the ion source must be run for 500 h continuously without maintenance. As a result of the beam test, the beam current and the emittance of 72 mA and 0.15 $$pi$$mm.mrad were achieved in the Cs seeded operation, respectively. Because a lifetime of the filament cathode is one of the main restrictions for the maintenance cycle, we started to perform a filament lifetime test. As the result of the test, we succeeded for 258 h arc operation at the arc power of 30 kW with the duty factor of 3 %. Moreover, the results showed that there is a possibility of achievement $$>$$800 h lifetime by change the connection between filament and arc power supply and the optimization of the filament shape.

Journal Articles

Development of a H$$^{-}$$ ion source for the high intensity proton linac at Japan Atomic Energy Research Institute

Oguri, Hidetomo; Tomisawa, Tetsuo; Kinsho, Michikazu; Okumura, Yoshikazu; Mizumoto, Motoharu

Review of Scientific Instruments, 71(2), p.975 - 977, 2000/02

 Times Cited Count:7 Percentile:51.13(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Development of an injector section for the high intensity proton accelerator at JAERI

Oguri, Hidetomo; Kinsho, Michikazu; Ouchi, Nobuo; Hasegawa, Kazuo; Kusano, Joichi; Mizumoto, Motoharu; Okumura, Yoshikazu; Touchi, Y.*

Proc. of 22nd Linear Accelerator Meeting in Japan, p.308 - 310, 1997/00

no abstracts in English

Oral presentation

Operation status of the J-PARC RF negative hydrogen ion source

Shinto, Katsuhiro

no journal, , 

no abstracts in English

Oral presentation

Behavior of H$$^-$$ beam extracted from a high-intensity rf-driven H$$^-$$ ion source

Shinto, Katsuhiro

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Influence of 30 MHz and 2 MHz RF plasma upon plasma electrode potential in the J-PARC RF-driven H$$^-$$ ion source

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

no journal, , 

For the application of bias voltage in J-PARC Radio Frequency (RF) negative ion source, characteristics of the voltage variation on the plasma electrode are investigated with different RF plasma conditions. A continuous 30 MHz RF power up to 10 - 100 W and a pulsed 2 MHz RF power up to 5 - 20 kW are injected from internal RF antenna coil. In each case, time structure of the voltage between the plasma electrode and the isolated source chamber is measured by voltage probe with different measurement resistances. Behavior of the measured voltage differs strongly whether the RF plasma is in the E mode phase by 30 MHz RF injection or in the H mode phase by 2 MHz RF injection. The results suggest that formation of capacitively coupled electric field and inductively coupled magnetic field decide the positive and the negative fluxes coming into the chamber wall. Under the same plasma condition as in the J-PARC user operation, peak value of the voltage between the source chamber and the plasma electrode is around 60 - 80 V and frequency of the voltage is a combination of 2 MHz and 30 MHz. For the continuous bias voltage application on the plasma electrode, additional distributed constant circuit to cancel these voltage oscillation and high voltage bias power supply are required.

Oral presentation

Optimization of beam extractor for J-PARC caesiated RF-driven H$$^{-}$$ ion source 100 mA operation

Ueno, Akira

no journal, , 

In a test-stand, the J-PARC caesiated RF-driven H$$^{-}$$ ion source succeeded in the stable operation with the beam duty factor of 5 % (1 ms $$times$$ 50 Hz), intensity of 100 mA and energy of 62 keV. The beam satisfied the beam qualities (transverse emittances of about 0.26$$pi$$mm$$cdot$$mrad) for the radio frequency quadruple linear accelerator of high energy linear accelerators with an acceleration efficiency more than 90 %. The beam was extracted from a plasma beam aperture with a 9 mm diameter, accelerated with a 3.2 mm extraction gap to 12 keV, passed through a extraction electrode with initial 7.1 mm and final 12.6 mm diameters and a thickness of 12.4 mm, and accelerated with a 7 mm acceleration gap to 62 keV. Since the 100 mA 62 keV beam was considered to be in a space-charge limited current condition, the extraction electrode thickness was reduced to 10.5 mm and the ground electrode was shifted 1.9 mm to upstream. The emittnace improvements with the optimization are reported.

Oral presentation

110 mA operation of J-PARC cesiated RF-driven H$$^{-}$$ ion source

Ueno, Akira

no journal, , 

On 2018, the stable operation of the J-PARC cesiated RF-driven H$$^{-}$$ ion source (IS) with a 62 keV 100 mA beam, whose emittances were suitable for the radio-frequency quadrupole LINAC (RFQ), was reported. In the J-PARC IS operation, the stable plasma production with a 50 kW 2 MHz RF power for more than 3 months and the possibility of the space charge limited beam intensity pulling up by increasing the extraction and acceleration voltages were proven. The stable operation results with a 65 keV 110 mA beam are presented. Since the 102.5 mA of the beam was measured inside the emittances used for the RFQ design, the RFQ with a 97.6% acceleration efficiency could accelerate a 100 mA beam.

Oral presentation

Operation experience of the J-PARC ion source

Oguri, Hidetomo

no journal, , 

no abstracts in English

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