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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：11 Percentile：67.3(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 
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 
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
cm to 400 Gasuscm. 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 1100 mm with a small amount increase of electron current of 10%. The obtained beam current fulfills the requirement for JT-60SA.
Akino, Noboru; Endo, Yasuei; Hanada, Masaya; Kawai, Mikito*; Kazawa, Minoru; Kikuchi, Katsumi*; Kojima, Atsushi; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; et al.
JAEA-Technology 2014-042, 73 Pages, 2015/02
JAEA-Technology-2014-042.pdf:15.1MB
According to the project plan of JT-60 Super Advanced that is implemented as an international project between Japan and Europe, the neutral beam (NB) injectors have been disassembled. The disassembly of the NB injectors started in November, 2009 and finished in January, 2012 without any serious problems as scheduled. This reports the disassembly activities of the NB injectors.
Komata, Masao; Shimizu, Tatsuo; Ozeki, Masahiro; Kojima, Atsushi; Hanada, Masaya
JAEA-Technology 2014-041, 50 Pages, 2015/01
JAEA-Technology-2014-041.pdf:22.68MB
In JT-60 Super Advanced, the machine for nuclear fusion research with superconducting magnets for long pulse operation, the negative-ion-base neutral beam injector is required to extend the pulse duration time 10 s to 100 s. In order to realize the long-pulse N-NB injector, the control system of the power supplies for the negative ion source has been newly developed. The control system with use of the versatile devices such as PLC was designed for an ease extension of the functions. Since the control system should have the many different functions which require the wide range of the sampling time of 1 milli-second to 10, all of the functions are performed by distributing PLCs for each of the function. The developed control system has been applied in the tests of the JT-60 negative ion source, where a 100 s negative ion beam has been successfully produced. Through this test, the controllability of this system has been confirmed to be feasible for JT-60SA operation.
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：14 Percentile：50.88(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
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 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.
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 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 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 and H.
Kobayashi, Takayuki; Isayama, Akihiko; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; Sato, Fumiaki; et al.
Nuclear Fusion, 51(10), p.103037_1 - 103037_10, 2011/10
Times Cited Count：19 Percentile：62.41(Physics, Fluids & Plasmas)A new gyrotron operation technique to increase oscillation efficiency was developed on the JT 60 ECRF system. The electron pitch factor was optimized by controlling anode voltage within 0.1 s after the start of the operation. By applying this technique, the gyrotron output power of 1.5 MW for 4 s was recorded, for the first time. The reduced collector heat load at 1.5 MW operations was reduced by 20% and it will be acceptable for longer pulse operation. A new gyrotron with an improved mode converter was developed in order to demonstrate reduction of the stray radiation which had limited the pulse length. The stray radiation was reduced to 1/3 of that of the original gyrotron. A conditioning operation of the improved gyrotron is proceeding up to 31 s at 1 MW. These progresses significantly contribute to enhancing the high power and long pulse capability of the ECRF system toward JT 60SA.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; Hiranai, Shinichi; et al.
no journal, ,
As a result of inspection of the ECRF antennas after the JT-60U operation, no large damages were found on them although the color of the mirror surfaces were slightly changed probably due to coating of thin film and some evidences of arcing were found. In the statistical analysis on the 9-year operation of the ECRF system, the success rate, which is defined as the ratio of actual injection time to preprogrammed one was higher than 0.85 in the last 3 years of the operation in average of 4 lines. To meet the long-pulse requirement of JT-60SA, development of long-pulse gyrotron with improved mode converter is on going aiming at 1 MW, 100 s. It was confirmed that the diffraction loss was remarkably decreased and the temperature of the DC break cooling water, which limited the pulse length, was saturated at about half of that before the improvement. As the result, the pulse length reached 17 s at 1 MW, and 30 s at 0.6 MW (18 MJ) recently, and further conditioning will be continued.
Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Hasegawa, Koichi; Suzuki, Sadaaki; Hiranai, Shinichi; Sato, Fumiaki; Wada, Kenji; Ozeki, Masahiro; Yokokura, Kenji; et al.
no journal, ,
On the design of an antenna for the electron cyclotron heating and current drive system in JT-60SA, the reduction of risk of water leakage in vacuum is proposed by means of linear motion antenna concept. We report results of a detail study of structural, mechanical and optical design for realizing this antenna. A mock-up of the steering structure, which is the most important part of this antenna and consists of a long stroke bellows for linear motion and a bellows which is deformed when the steering shaft is rotated, was fabricated. By testing the mock-up, it was clarified that the beam injection angle range required in JT-60SA is realized by this antenna. Moreover, we confirmed that the beam profile obtained by low power measurements, in which beam angle was changed in two directions, agree with calculated profile.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Terakado, Masayuki; et al.
no journal, ,
no abstracts in English
Hiranai, Shinichi; Suzuki, Sadaaki; Sato, Fumiaki; Wada, Kenji; Ozeki, Masahiro; Kobayashi, Takayuki; Hasegawa, Koichi; Yokokura, Kenji; Moriyama, Shinichi
no journal, ,
no abstracts in English
Komata, Masao; Hanada, Masaya; Akino, Noboru; Kazawa, Minoru; Ozeki, Masahiro; Kawai, Mikito*; Otsuki, Shinichi*
no journal, ,
no abstracts in English
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 
10% without a reduction of the negative ion production.
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
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 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 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.
Komata, Masao; Shimizu, Tatsuo; Ozeki, Masahiro; Kojima, Atsushi; Hanada, Masaya
no journal, ,
no abstracts in English
Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Umeda, Naotaka; Hiratsuka, Junichi; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; et al.
no journal, ,
One of the key issues for producing high current beams in JT-60SA is a uniform production of the negative ions over the large ion extraction area. Non-uniformity of the negative ion beams in the JT-60 negative ion source was improved by modifying the magnetic filter in the source from the PG filter to a tent-shaped filter. In this work, in order to clarify the influence of the magnetic filter modification on arc efficiency and co-electron current is investigated by means of measurements of H ion, H atoms, co-electron current and beam intensity. As a result, the arc efficiency increase due to increase of H ions and H atoms by reduction of filter field. Although the higher electrons current was extracted than the original PG filter, the co-extracted electron could be suppressed by optimization of the bias voltage. This result contributes to extend the pulse duration time up to 100 s for JT-60SA.
Hanada, Masaya; Kojima, Atsushi; Akino, Noboru; Komata, Masao; Mogaki, Kazuhiko; Sasaki, Shunichi; Nemoto, Shuji; Shimizu, Tatsuo; Ozeki, Masahiro; Oasa, Kazumi; et al.
no journal, ,
This paper reports the present status of the research and developments to realize the neutral beam (NB) injectors for JT-60 SA where a total injection power and pulse duration time are 34 MW and 100 s, respectively. The research and development for the positive-ion-based NB injector has been well in progress, which ensures to inject 24 MW, 85 keV for 100 s from twelve injectors. As for the negative-ion-based NB (N-NB) injector, the performance of the negative ion beam has been energetically improved by modifying the JT-60 negative ion source to realize a 10 MW, 500 keV for 100 s. The achievements of the beam performance fulfills the beam current of 22A, the beam energy of 500 keV, pulse duration time of 100 s required for JT-60 SA independently. In addition, the long pulse production of the high-current beam is being tested, where 15 A of the high-current beam is produced for 100 s.
Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Tobari, Hiroyuki; Hiratsuka, Junichi; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; et al.
no journal, ,
no abstracts in English
Sasaki, Shunichi; Hanada, Masaya; Akino, Noboru; Kojima, Atsushi; Komata, Masao; Mogaki, Kazuhiko; Endo, Yasuei; Shimizu, Tatsuo; Ozeki, Masahiro; Nemoto, Shuji
no journal, ,
no abstracts in English
Sasaki, Shunichi; Hanada, Masaya; Akino, Noboru; Endo, Yasuei; Shimizu, Tatsuo; Ozeki, Masahiro
no journal, ,
no abstracts in English
