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Journal Articles

Acceleration of MeV-class energy, high-current-density H$$^{-}$$-ion beams for ITER neutral beam system

Taniguchi, Masaki; Inoue, Takashi; Kashiwagi, Mieko; Watanabe, Kazuhiro; Hanada, Masaya; Seki, Takayoshi*; Dairaku, Masayuki; Sakamoto, Keishi

Review of Scientific Instruments, 77(3), p.03A514_1 - 03A514_4, 2006/03

 Times Cited Count:13 Percentile:57.01(Instruments & Instrumentation)

In the ITER NB systems, conventional gas insulation technology cannot be utilized because of the conductivity of the insulation gas caused by the radiation from the tokamak plasma. To overcome this problem, a vacuum insulated beam source (VIBS), where the whole beam source is immersed in vacuum, has been developed in JAERI. Recently, voltage holding capability of the VIBS was drastically improved by installing the large stress ring and these progress enables us to perform the high power operation of the VIBS accelerator. For high current density H$$^{-}$$- beam acceleration, modifications were made on KAMABOKO source. At present, H$$^{-}$$- beam current density is 146 A/m$$^{2}$$ at 836 keV (input arc power; 40 kW, operation pressure; 0.3 Pa).The acceleration of 900 keV, 0.1 A level beam was accomplished for 175 shots during the test campaign. The beam acceleration was quite stable and the degradation of the voltage holding due to the beam acceleration and/or Cs seeding was not observed.

Journal Articles

Improvement of beam uniformity by magnetic filter optimization in a Cs-seeded large negative-ion source

Hanada, Masaya; Seki, Takayoshi*; Takado, Naoyuki*; Inoue, Takashi; Tobari, Hiroyuki; Mizuno, Takatoshi*; Hatayama, Akiyoshi*; Dairaku, Masayuki; Kashiwagi, Mieko; Sakamoto, Keishi; et al.

Review of Scientific Instruments, 77(3), p.03A515_1 - 03A515_3, 2006/03

 Times Cited Count:24 Percentile:73.73(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Beam deflection by plasma grid filter current in the negative-ion source for JT-60U neutral beam injection system

Umeda, Naotaka; Ikeda, Yoshitaka; Hanada, Masaya; Inoue, Takashi; Kawai, Mikito; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Oga, Tokumichi

Review of Scientific Instruments, 77(3), p.03A529_1 - 03A529_3, 2006/03

 Times Cited Count:5 Percentile:31.18(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Development of an H$$^{-}$$-ion source for the High-Intensity Proton Accelerator (J-PARC)

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

Review of Scientific Instruments, 77(3, Part2), p.03A517_1 - 03A517_3, 2006/03

 Times Cited Count:5 Percentile:31.18(Instruments & Instrumentation)

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.

Journal Articles

Acceleration of high current fully stripped carbon ion beam by direct injection scheme

Kashiwagi, Hirotsugu; Fukuda, Mitsuhiro; Okamura, Masahiro*; Jameson, R. A.*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Sakakibara, Kazuhiko*; Takano, Jumpei*; Yamamoto, Kazuo*; Iwata, Yoshiyuki*; et al.

Review of Scientific Instruments, 77(3), p.03B305_1 - 03B305_4, 2006/03

 Times Cited Count:12 Percentile:54.47(Instruments & Instrumentation)

Acceleration of a 17mA 100keV/u C$$^{6+}$$ ion beam has been successfully achieved with an RFQ linac by means of "Direct injection scheme". The Direct injection scheme is a new scheme for injecting an ion beam from a laser ion source to the RFQ linac without a low energy beam transport line to avoid a beam loss due to the space charge effect. The high current C$$^{6+}$$ beam is required for single turn injection to a synchrotron to reduce the size of synchrotron magnets. The high current C$$^{6+}$$ beam produced by an ion source with a Nd-YAG laser was injected to the RFQ linac by the Direct injection scheme. It has been proved experimentally that the fully-stripped carbon ion beam with a current more than 10mA can be accelerated by the RFQ linac.

Journal Articles

High current carbon beam production with direct plasma injection scheme

Okamura, Masahiro*; Kashiwagi, Hirotsugu; Sakakibara, Kazuhiko*; Takano, Jumpei*; Hattori, Toshiyuki*; Hayashizaki, Noriyosu*; Jameson, R. A.*; Yamamoto, Kazuo*

Review of Scientific Instruments, 77(3), p.03B303_1 - 03B303_3, 2006/03

 Times Cited Count:10 Percentile:49.28(Instruments & Instrumentation)

We have been studying a new heavy-ion production technique called "direct plasma injection scheme", DPIS, since 2000. A new radio frequency quadrupole "RFQ" designed especially for the DPIS was commissioned in 2004 and very intense carbon beam was successfully obtained, reaching more than 60 mA accelerated current from the RFQ. Most of the contents of the accelerated beam was carbon 4+ as verified by beam analysis.

Journal Articles

Analysis of laser-produced heavy ions for direct plasma injection scheme

Sakakibara, Kazuhiko*; Okamura, Masahiro*; Kondrashev, S.*; Hattori, Toshiyuki*; Kashiwagi, Hirotsugu; Kanesue, Takeshi*

Review of Scientific Instruments, 77(3), p.03B304_1 - 03B304_3, 2006/03

 Times Cited Count:2 Percentile:15.45(Instruments & Instrumentation)

To accelerate highly charged intense ion beam, we have developed the direct plasma injectionscheme DPIS with laser ion source. In this scheme an ion beam from a laser ion source is injecteddirectly to a radio frequency quadrupole RFQ linac without a low energy beam transport LEBT line and then beam losses in the LEBT can be avoided. We achieved high current acceleration ofcarbon ions 60 mA by DPIS with the RFQ specially designed for high current heavy ions. As thenext step we will use heavier elements such as Al, Fe, and Ta as targets in laser ion source usinghigh power laser, for example, glass laser for DPIS and will examine properties of laser-producedplasma for highly charged ion production.

Journal Articles

Numerical analysis of primary electrons in a tandem-type negative ion source

Kato, Kyohei*; Takado, Naoyuki*; Hatayama, Akiyoshi*; Hanada, Masaya; Seki, Takayoshi; Inoue, Takashi

Review of Scientific Instruments, 77(3), p.03A535_1 - 03A535_3, 2006/03

 Times Cited Count:12 Percentile:54.47(Instruments & Instrumentation)

To clarify physics mechanism of plasma spatial nonuniformity observed in tandem-type negative-ion sources, primary electron-transport process has been analyzed by a three-dimensional Monte Carlo simulation code. In the model, equations of motion for electrons are numerically solved. Geometry and magnetic-field configuration of the JAEA 10 Ampere negative ion source are taken into account. Various collision processes with neutral particles are also included in the model. The simulation results show that (1) the primary electrons have been lost from the source region to the extraction region due to magnetic drift in the magnetic filter, and then (2) there is another magnetic drift near the sidewalls, where a sum of magnetic field of the filter and the cusp field for plasma confinement allows electron drift towards the extraction region. A sequence of these magnetic drifts would increase the electron temperature in local area of extraction region, which resulted in loss of negative ions.

Journal Articles

Numerical analysis of the spatial nonuniformity in a Cs-seeded H$$^{-}$$ ion source

Takado, Naoyuki*; Hanatani, Junji*; Mizuno, Takatoshi*; Kato, Kyohei*; Hatayama, Akiyoshi*; Hanada, Masaya; Seki, Takayoshi; Inoue, Takashi

Review of Scientific Instruments, 77(3), p.03A533_1 - 03A533_3, 2006/03

 Times Cited Count:14 Percentile:59.05(Instruments & Instrumentation)

Surface production and transport process of H$$^{-}$$ ions are numerically simulated to clarify the origin of H$$^{-}$$ beam non-uniformity. A three-dimensional transport code using Monte Carlo method has been applied to productions of H$$^{0}$$ atoms and H$$^{-}$$ ions in a large negative ion source under the Cs seeded condition. The results show that a large fraction of hydrogen atoms are produced in a high electron temperature region. This leads to a spatial non-uniformity of H$$^{0}$$ atom flux to the plasma grid where H$$^{0}$$ atoms capture electrons and converted to H$$^{-}$$ ions. In addition, most surface-produced H$$^{-}$$ ions are extracted even through the high electron temperature region without destruction.

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