Wada, Motoi*; Shinto, Katsuhiro; Shibata, Takanori*; Sasao, Mamiko*
Review of Scientific Instruments, 91(1), p.013330_1 - 013330_5, 2020/01
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.
Purazuma, Kaku Yugo Gakkai-Shi, 95(7), p.340 - 344, 2019/07
no abstracts in English
Shibata, Takanori*; Ikegami, Kiyoshi*; Liu, Y.*; Miura, Akihiko; Naito, Fujio*; Nammo, Kesao*; Oguri, Hidetomo; Okoshi, Kiyonori; Otani, Masashi*; Shinto, Katsuhiro; et al.
Proceedings of 29th International Linear Accelerator Conference (LINAC 2018) (Internet), p.519 - 521, 2019/01
Transport process of negative hydrogen ion (H) in LEBT (Low Energy Beam Transport) is investigated by comparison of experimental and numerical results. A three dimensional Particle-In-Cell (PIC) particle transport model has been developed in order to take into account (i) axial magnetic field by two solenoids in J-PARC LEBT and (ii) radial electric field by space charge (SC) effect. Ratio of H beam particles inside the RFQ (Radio Frequency Quadrupole) acceptance to the total particles at the RFQ entrance is calculated for different current conditions in LEBT solenoid 1 and 2. The results are compared with RFQ transmission rate measured in the J-PARC linac commissioning. The double peak of RFQ transmission rate to the solenoid applied current seen in the measurement is explained by the calculation results. The results indicate that presence of the LEBT orifice for differential pumping plays a role as a collimator to reduce emittance at RFQ entrance.
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
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.
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
Shinto, Katsuhiro; Shibata, Takanori*; Miura, Akihiko; Miyao, Tomoaki*; Wada, Motoi*
AIP Conference Proceedings 2011, p.080016_1 - 080016_3, 2018/09
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
Miura, Akihiko; Moriya, Katsuhiro; Miyao, Tomoaki*
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.5022 - 5025, 2018/06
A wire-scanner monitor using metallic wire is reliably employed for the beam-profile measurement in the J-PARC linac. Because the loading of negative hydrogen (H) ion beam on a wire increases under high-current beam operation, we focus on using a high-durability beam profile monitors by attaching another wire material. Carbon nanotubes (CNT) are made of graphite in a cylindrical shape and have a tensile strength not less than 100 times that of steel. The electric conductivity has higher than that of metals, and hardness is endured thermally around 3000C in a vacuum circumstance. We applied the wires made from CNT to WSM and measured transverse profiles with a 3-MeV H beam. As a result, we obtained the equivalent signal levels taken by carbon wire made of polyacrylonitrile without any damage. In this paper, the signal response when the CNT is irradiated with an H beam and the result of beam profile measurement. In addition, the surface of CNT after 3-MeV beam operation was observed.
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.
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
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.
New Journal of Physics (Internet), 19(1), p.015004_1 - 015004_15, 2017/01
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 mmmrad, 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 mmmrad and an intensity of 66 mA.
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
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.
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
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.
Oguri, Hidetomo; Ueno, Akira; Namekawa, Yuya*; Ikegami, Kiyoshi*
Review of Scientific Instruments, 77(3, Part2), p.03A517_1 - 03A517_3, 2006/03
The J-PARC Project was started in 2001 as a joint project carried out by JAERI and KEK. At the first stage of the J-PARC, the linac will accelerate the H- ion beam current of 30 mA with a duty factor of 1.25 %. The J-PARC H- ion source driven with a LaB6 filament has regularly delivered more than 35 mA beam with a duty factor of 0.9 % without resorting to cesium. Although the operated duty factor is about 1/3 of the requirement, the filament is not replaced for a half year. At the J-PARC, the lifetime of the tungsten (W) filament was measured by using another H- ion source, which can produce a 72 mA with cesium seeded. The experimental results showed that there is a possibility of the W filament satisfying the lifetime of more than 500 hours, which is J-PARC requirement. We consider the W driven plasma ion source is one of the candidates for the J-PARC source. At present, we are performing the beam test of the cesium free ion source driven with W. We will present the experimental data of the beam test in this conference.
Oguri, Hidetomo; Namekawa, Yuya*
JAERI-Tech 2004-053, 35 Pages, 2004/07
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 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 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.
Proceedings of 22nd International Linear Accelerator Conference (LINAC 2004), p.554 - 558, 2004/00
no abstracts in English
Meigo, Shinichiro; Hasegawa, Kazuo; Ikeda, Yujiro; Oigawa, Hiroyuki; Aoki, Nobutada*; Nakagawa, S.*
JAERI-Tech 2002-095, 40 Pages, 2002/12
no abstracts in English
Shimooka, Takashi; Oguri, Hidetomo; Namekawa, Yuya*; Tomisawa, Tetsuo; Okumura, Yoshikazu; Hasegawa, Kazuo
JAERI-Tech 2002-038, 30 Pages, 2002/03
The high intensity proton accelerator facility project which is conducted jointly by JAERI and KEK is to use the secondary particles produced by nuclear spallation for various science studies. A negative hydrogen ion beam source for the accelerator is required to extract a peak beam current of more than 60 mA with a duty factor of 2.5 %. In addition, the ions should be negatively charged in order to improve the capture efficiency of the beam injected into a synchrotron. At JAERI, a negative ion source for the project has been developed with various technologies based on the large negative ion source for the nuclear fusion application. The negative ion beam current and the rms normalized emittance of 72 mA and 0.15 mm.mrad were achieved in the cesium seeded operation, respectively. A waveform of the pulsed beam current was sensitive to the operation gas flow rate, and became to have a good flatness at about 16 SCCM. These results show that the basic performance of the ion source satisfies the requirement of the ion source for the project.
Hasegawa, Kazuo; Kato, Takao*; JAERI-KEK Superconduction Proton Linac Development Team
JAERI-Conf 2001-002, p.185 - 190, 2001/03
no abstracts in English
Oguri, Hidetomo; Tomisawa, Tetsuo; Kinsho, Michikazu; Okumura, Yoshikazu; Mizumoto, Motoharu
Review of Scientific Instruments, 71(2), p.975 - 977, 2000/02
no abstracts in English