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Journal Articles

22A beam production of the uniform negative ions in the JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Grisham, L. R.*; Hatayama, Akiyoshi*; Shibata, Takanori*; Yamamoto, Takashi*; Akino, Noboru; Endo, Yasuei; et al.

Fusion Engineering and Design, 96-97, p.616 - 619, 2015/10

 Times Cited Count:9 Percentile:24.84(Nuclear Science & Technology)

In JT-60 Super Advanced for the fusion experiment, 22A, 100s negative ions are designed to be extracted from the world largest ion extraction area of 450 mm $$times$$ 1100 mm. One of the key issues for producing such as high current beams is to improve non-uniform production of the negative ions. In order to improve the uniformity of the negative ions, a tent-shaped magnetic filter has newly been developed and tested for JT-60SA negative ion source. The original tent-shaped filter significantly improved the logitudunal uniformity of the extracted H$$^{-}$$ ion beams. The logitudinal uniform areas within a $$pm$$10 deviation of the beam intensity were improved from 45% to 70% of the ion extraction area. However, this improvement degrades a horizontal uniformity. For this, the uniform areas was no more than 55% of the total ion extraction area. In order to improve the horizontal uniformity, the filter strength has been reduced from 660 Gasus$$cdot$$cm to 400 Gasus$$cdot$$cm. This reduction improved the horizontal uniform area from 75% to 90% without degrading the logitudinal uniformity. This resulted in the improvement of the uniform area from 45% of the total ion extraction areas. This improvement of the uniform area leads to the production of a 22A H$$^{-}$$ ion beam from 450 mm $$times$$ 1100 mm with a small amount increase of electron current of 10%. The obtained beam current fulfills the requirement for JT-60SA.

JAEA Reports

Measurement of pure water resistivity in a high temperature region

Yamanaka, Haruhiko; Maejima, Tetsuya; Terunuma, Yuto; Watanabe, Kazuhiro; Kashiwagi, Mieko; Hanada, Masaya

JAEA-Technology 2014-037, 12 Pages, 2014/12

JAEA-Technology-2014-037.pdf:4.27MB

Resistivity of a high temperature pure water has been measured up to 180$$^{circ}$$C which is the maximum water temperature in the ITER Neutral Beam Injector. The resistivity of the pure water is decreased by increasing the water temperature. It was found that even different resistivity water of 9 M$$Omega$$cm and 5 M$$Omega$$cm showed almost the same resistivity at the higher temperature region of 100$$^{circ}$$C. The resistivity of 0.36 M$$Omega$$cm was measured at the temperature of 180$$^{circ}$$C. This resistivity agreed well to the calculated value for the theoretical pure water.

Journal Articles

Improvement of uniformity of the negative ion beams by Tent-shaped magnetic field in the JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Grisham, L. R.*; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; et al.

Review of Scientific Instruments, 85(2), p.02B314_1 - 02B314_4, 2014/02

 Times Cited Count:10 Percentile:46.97(Instruments & Instrumentation)

Non-uniformity of the negative ion beams in the JT-60 negative ion source was improved by modifying an external magnetic field to a tent-shaped magnetic field for reduction of the local heat loads in the source. Distributions of the source plasmas (H$$^{+}$$ ions and H$$^{0}$$ atoms) of the parents of H$$^{-}$$ ions converted on the cesium covered plasma grids were measured by Langmuir probes and emission spectroscopy. Beam intensities of the H$$^{-}$$ ions extracted from the plasma grids were measured by IR camera from the back of the beam target plate. The tent-shaped magnetic field prevented the source plasmas to be localized by B $$times$$ grad B drift of the primary electrons emitted from the filaments in the arc chamber. As a result, standard derivation of the H$$^{-}$$ ions beams was reduced from 14% (the external magnetic field) to 10% (the tent-shaped magnetic field) without reduction of an activity of the H$$^{-}$$ ion production.

Journal Articles

Origin of non-uniformity of the source plasmas in JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Kashiwagi, Mieko; Grisham, L. R.*; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; et al.

Plasma and Fusion Research (Internet), 8(Sp.1), p.2405146_1 - 2405146_4, 2013/11

Distributions of H$$^{0}$$ and H$$^{+}$$ in the source plasmas produced at the end-plugs of JT-60 negative ions source were measured by Langmuir probes and emission spectroscopy in order to experimentally investigate the cause of lower density of the negative ions extracted from end-plugs in the source. Densities of H$$^{0}$$ and H$$^{+}$$ in end-plugs of the plasma grid in the source were compared with those in the center regions. As a result, lower density of the negative ion at the edge was caused by lower beam optics due to lower and higher density of the H$$^{0}$$ and H$$^{+}$$.

Oral presentation

Long pulse operation of power supply is for the JT-60 negative ion source

Sasaki, Shunichi; Endo, Yasuei; Terunuma, Yuto; Hanada, Masaya; Kojima, Atsushi

no journal, , 

no abstracts in English

Oral presentation

Improvement of uniformity of the negative ion beams by tent-shaped magnetic field in the JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; Ozeki, Masahiro; et al.

no journal, , 

Non-uniformity of the negative ion beams in the JT-60 negative ion source with the world-largest ion extraction area was improved by modifying the magnetic filter in the source from the PG filter to a tent-shaped filter. The magnetic design via electron trajectory calculation showed that the tent-shaped filter was expected to suppress the localization of the primary electrons emitted from the filaments and created uniform plasma with positive ions and atoms of the parent particles for the negative ions. By modifying the magnetic filter to the tent-shaped filter, the uniformity defined as the deviation from the averaged beam intensity was reduced from 14% of the PG filter to $$sim$$10% without a reduction of the negative ion production.

Oral presentation

Present status of procurement activities for ITER NB system

Tobari, Hiroyuki; Hanada, Masaya; Watanabe, Kazuhiro; Kashiwagi, Mieko; Dairaku, Masayuki; Yamanaka, Haruhiko; Maejima, Tetsuya; Umeda, Naotaka; Abe, Hiroyuki; Terunuma, Yuto; et al.

no journal, , 

JAEA has started procurement activities for ITER NB test facility (NBTF). NBTF being under construction in Padova, Italy has an objective to establish beam technology for 1 MeV, 40 A D- beam prior to ITER operation. JAEA procures high voltage components of 1 MV power supply such as insulating transformer and HV bushing as insulating feedthrough. Requirements to realize those components exceeds existing technology level, hence JAEA has pushed R&D. As for 1 MV insulating transformer, insulating method with double-walled insulator was newly developed. As for the HV bushing, a new forming method of the world largest ceramic ring and brazing technique were developed, and then a technology that meets ITER requirement has been confirmed. Procurement activities have been started from 2012 and now is undergoing as scheduled. Manufacturing of components will be completed by 2015 and those will be transported and installed in Padova in 2016. Commissioning will start in 2017.

Oral presentation

Progress of procurement of the ITER NB power supplies

Yamanaka, Haruhiko; Watanabe, Kazuhiro; Kashiwagi, Mieko; Tobari, Hiroyuki; Maejima, Tetsuya; Hanada, Masaya; Terunuma, Yuto

no journal, , 

A high-energy and high power neutral beam injectors (NBI) of 1 MeV, 16.5 MW neutral power/injector are required for plasma heating and current drive in ITER. A Neutral Beam Test Facility (NBTF), which has the same capacity as the ITER NBI, is constructed at the RFX site in Padua of Italy to demonstrate the specifications and to establish its operation techniques. Capacity of the power supply is DC -1 MV and 60 MW for the beam source with pulse duration up to 3600 s. JAEA as Japan Domestic Agency (JADA) provides ultra-high voltage components of a DC -1 MV power supply for NBTF. To fabricate such UHV NBI power supply components, detailed design has been conducted.

Oral presentation

Improvement of uniformity of the negative ion beams by Tent-shaped magnetic field in JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; Ozeki, Masahiro; et al.

no journal, , 

no abstracts in English

Oral presentation

Progress of procurement of the ITER NB power supplies

Maejima, Tetsuya; Watanabe, Kazuhiro; Kashiwagi, Mieko; Yamanaka, Haruhiko; Terunuma, Yuto; Umeda, Naotaka; Dairaku, Masayuki; Tobari, Hiroyuki; Yamashita, Yasuo*; Shibata, Naoki; et al.

no journal, , 

no abstracts in English

Oral presentation

22A production of uniform negative ion beams in the JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; Ozeki, Masahiro; et al.

no journal, , 

In JT-60SA for the fusion experiment, 22A, 100s D$$^{-}$$ ions are designed to be extracted from the world largest ion extraction area of 450 mm $$times$$ 1100 mm. One of the key issues for producing such as high current beams is to improve non-uniform production of the negative ions. In order to improve the uniformity of the negative ions, a tent-shaped magnetic filter has newly been developed and tested for JT-60SA negative ion source. The non-uniformity of the negative ions is experimentally found to be caused by a localization of H$$^{+}$$ ions and H$$^{0}$$ atoms, which are produced by primary electrons emitted from filaments and are converted to H$$^{-}$$ ions on the surface of plasma grids covered with cesium. By modifying from the conventional magnetic filter to the tent-shaped one, the uniform areas were expanded from 45% of the full extraction areas in the conventional magnetic filter to 60%. Finally, 22A production of the negative ion beams was successfully achieved in the uniform areas.

Oral presentation

Experimental study on electrical characteristics of a high temperature pure water for quality improvement of the ITER neutral beam injector power supply

Yamanaka, Haruhiko; Watanabe, Kazuhiro; Kashiwagi, Mieko; Maejima, Tetsuya; Terunuma, Yuto; Umeda, Naotaka; Dairaku, Masayuki; Tobari, Hiroyuki; Hanada, Masaya

no journal, , 

no abstracts in English

Oral presentation

Development of DC ultra-high voltage insulation technology for ITER NBI

Tobari, Hiroyuki; Hanada, Masaya; Watanabe, Kazuhiro; Kashiwagi, Mieko; Kojima, Atsushi; Dairaku, Masayuki; Seki, Norikatsu; Abe, Hiroyuki; Umeda, Naotaka; Yamanaka, Haruhiko; et al.

no journal, , 

Progress on technical development on ITER and JT-60SA neutral beam injector (NBI) were reported. In development of a 1 MV insulating transformer for ITER NB power supply, a bushing extracting 1 MV required a huge insulator that was impossible to manufacture. To solve this issue, a composite bushing with FRP tube and a small condenser bushing with insulation gas was newly developed. In development the HV bushing as an insulating feed through, voltage holding in large cylindrical electrodes inside the HV bushing was investigated. The scaling for vacuum insulation design of large cylindrical electrodes was obtained. Toward long pulse production and acceleration of negative ion beam, active control system of plasma grid temperature and a new extractor consisting of the extraction grid with high water cooling capability and aperture offset were developed. As a result, 15 negative ion beam has been achieved for 100 s. Also beam energy density has been increased two orders of magnitude.

Oral presentation

Manufacturing and tests of 1MV power supply for ITER NBTF

Kashiwagi, Mieko; Watanabe, Kazuhiro; Yamanaka, Haruhiko; Maejima, Tetsuya; Terunuma, Yuto*; Oda, Yuki; Tobari, Hiroyuki; Dairaku, Masayuki; Hanada, Masaya

no journal, , 

Toward the neutral beam (NB) system of ITER, the prototype of the ITER NB is under construction in the NB test facility (NBTF), Padova, Italy. For the NBTF, Japan Atomic Energy Agency manufactures, transports and constructs the 1MV high voltage power supply components to generate 1 MV, 60 A for 3600 s, which consist of fourteen components such as five DC generators and transmission lines with 100 m in a length. The manufacturing of the power supply components is in progress as scheduled. Three of five DCGs and 80% of the transmission lines have been completed. In the factory, the voltage holding test including the margin of 20% were successfully demonstrated. Then, these are under transportation to the NBTF. The construction work is started from Dec/2015 as scheduled. As the one of R&Ds results, the development of the water choke made of fiber reinforced plastic (FRP) is reported, which is the alternative of the conventional ceramic.

Oral presentation

Experimental study on electrical characteristics of a high temperature pure water and progress status of the ITER neutral beam injector power supply

Yamanaka, Haruhiko; Watanabe, Kazuhiro; Kashiwagi, Mieko; Maejima, Tetsuya; Terunuma, Yuto; Umeda, Naotaka; Dairaku, Masayuki; Tobari, Hiroyuki; Hanada, Masaya

no journal, , 

no abstracts in English

15 (Records 1-15 displayed on this page)
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