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JAEA Reports

Modification of power supplies in the negative-ion-based NBI system for a 100s operation in JT-60SA

Usui, Katsutomi; Noto, Katsuya; Kawai, Mikito; Oga, Tokumichi*; Ikeda, Yoshitaka

JAEA-Technology 2008-053, 35 Pages, 2008/08

JAEA-Technology-2008-053.pdf:10.56MB

The JT-60 negative ion-based NBI (N-NBI) system is required to extend the pulse duration from 30s to 100s in JT-60SA that is the modified JT-60U with full superconducting coils. The JT-60SA N-NBI system will have 2 ion sources, each of which will inject 5 MW at 500 keV. The present power supply system should be upgraded to operate for 100s with minimizing the modification of existing components. The protective characteristic and thermal capacities of the power supply components were assessed based on the experience of the modification for the 30s operation in 2003. The acceleration power supply is to be modified with combination of existing Gate Turnoff Thyristors (GTO) and Injection Enhanced Gate Transistors (IEGT) added newly. Five power supplies for a plasma production in the negative ion sources are to be modified by increasing the capacities of the partial resistance and cooling systems. These modifications can allow the long pulse operation of 100 for JT-60SA N-NBI system.

Journal Articles

Technical design of NBI system for JT-60SA

Ikeda, Yoshitaka; Akino, Noboru; Ebisawa, Noboru; Hanada, Masaya; Inoue, Takashi; Honda, Atsushi; Kamada, Masaki; Kawai, Mikito; Kazawa, Minoru; Kikuchi, Katsumi; et al.

Fusion Engineering and Design, 82(5-14), p.791 - 797, 2007/10

 Times Cited Count:19 Percentile:79.3(Nuclear Science & Technology)

Modification of JT-60U to a superconducting device (so called JT-60SA) has been planned to contribute to ITER and DEMO. The NBI system is required to inject 34 MW for 100 s. The upgraded NBI system consists of twelve positive ion based NBI (P-NBI) units and one negative ion based NBI (N-NBI) unit. The injection power of the P-NBI units are 2 MW each at 85 keV, and the N-NBI unit will be 10 MW at 500 keV, respectively. On JT-60U, the long pulse operation of 30 s at 2 MW (85 keV) and 20 s at 3.2 MW (320 keV) have been achieved on P-NBI and N-NBI units, respectively. Since the temperature increase of the cooling water in both ion sources is saturated within 20 s, further pulse extension up to 100 s is expected to mainly modify the power supply systems in addition to modification of the N-NBI ion source for high acceleration voltage. The detailed technical design of the NBI system for JT-60SA is presented.

JAEA Reports

Study on modification of power supply system for long pulse operation on JT-60 positive ion-based NBI

Usui, Katsutomi; Noto, Katsuya; Kawai, Mikito; Oga, Tokumichi*; Ikeda, Yoshitaka

JAEA-Technology 2007-024, 32 Pages, 2007/03

JAEA-Technology-2007-024.pdf:7.54MB

The JT-60 positive ion-based NBI (P-NBI) system is required to extend the pulse duration from 30 s to 100 s for JT-60SA, which is the modification of JT-60U to a fully superconducting coil tokamak. The JT-60SA NBI system will have 12 P-NBI units, each of which will inject 2 MW at 85 keV. The present power supply system is to be upgraded to operate for 100 s with minimum modification. The modification of the power supply has been studied in view of the protective characteristic and the thermal capacities of main power supply components. The design study is based on the results of the first modification of 30 s operation which was done in 2003. It has been confirmed that the long pulse operation of 100 s is possible by with partial modification of the power supply components such as enhancement of the water-cooled resistance of the acceleration power supply.

Journal Articles

Present status of the negative ion based NBI system for long pulse operation on JT-60U

Ikeda, Yoshitaka; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hanada, Masaya; Honda, Atsushi; Inoue, Takashi; Kawai, Mikito; Kazawa, Minoru; et al.

Nuclear Fusion, 46(6), p.S211 - S219, 2006/06

 Times Cited Count:52 Percentile:86.86(Physics, Fluids & Plasmas)

Recently, the extension of the pulse duration up to 30 sec has been intended to study quasi-steady state plasma on JT-60U N-NBI system. The most serious issue is to reduce the heat load on the grids for long pulse operation. Two modifications have been proposed to reduce the heat load. One is to suppress the beam spread which may be caused by beamlet-beamlet interaction in the multi-aperture grid due to the space charge force. Thin plates were attached on the extraction grid to modify the local electric field. The plate thickness was optimized to steer the beamlet deflection. The other is to reduce the stripping loss, where the electron of the negative ion beam is stripped and accelerated in the ion source and then collides with the grids. The ion source was modified to reduce the pressure in the accelerator column to suppress the beam-ion stripping loss. Up to now, long pulse injection of 17 sec for 1.6 MW and 25 sec for $$sim$$1 MW has been obtained by one ion source with these modifications.

JAEA Reports

Characteristics of voltage holding and outgassing on the accelerator of JT-60 N-NBI ion source

Kikuchi, Katsumi; Akino, Noboru; Ikeda, Yoshitaka; Usui, Katsutomi; Umeda, Naotaka; Oga, Tokumichi; Kawai, Mikito; Mogaki, Kazuhiko

JAEA-Technology 2006-016, 25 Pages, 2006/03

JAEA-Technology-2006-016.pdf:2.54MB

The 500 keV negative-ion based neutral beam injector (NBI) has been operated to heat plasma and drive plasma current on JT-60U since 1996. The ion source was designed to accelerate the negative ions up to 500 keV. During the last 10 years, the accelerated voltage of the negative ion beam has been limited to $$sim$$400 keV by breakdowns in the accelerator. To understand the breakdown phenomena, the characteristics of the voltage holding of the ion source were studied without beam extraction. Outgassing with the main species of m/e=28 was observed when high voltage was applied even without breakdowns. It was noticed that the fraction of the main species at breakdown was almost the same as without breakdowns. Conditioning reduced the outgassing and resulted in improvement of the voltage holding capability. Inside the ion source, a brightening was observed even without breakdown. The brightening intensity was suppressed by increasing the D$$_{2}$$ pressure in the accelerator in the range of 10$$^{-4}$$ Pa to 0.5 Pa. Since the voltage holding was also improved with D$$_{2}$$ pressure, breakdowns seemed to correlate with the brightening phenomena in the accelerator. This report gives the preliminary results of outgassing and brightening measurements when the high voltage was applied on the accelerator without beam extraction.

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

Recent progress of negative ion based neutral beam injector for JT-60U

Umeda, Naotaka; Yamamoto, Takumi; Hanada, Masaya; Grisham, L. R.*; Kawai, Mikito; Oga, Tokumichi; Akino, Noboru; Inoue, Takashi; Kazawa, Minoru; Kikuchi, Katsumi*; et al.

Fusion Engineering and Design, 74(1-4), p.385 - 390, 2005/11

 Times Cited Count:9 Percentile:55.58(Nuclear Science & Technology)

In negative ion based neutral beam injector (N-NBI) for JT-60U, some modifications for extent pulse duration from 10 second, which is design value, to 30 second was conducted. Main limit to prevent pulse extension was heat loads onto grounded grid in an ion source and onto beam limiter placed at 22 m from the ion source. To reduce these heat loads, beam extraction area was optimized and the limiter was changed to one which had about twice thermal capacity. As a result of these modifications, the temperature rise of the water which was cooling grounded grid could be suppressed under 40 degree, which can operate in steady state condition. The temperature rise of the limiter could be restricted to 60%. Untill now the beam pulse extended to 17 second of 1.6MW power at 366keV energy, and injection of 30 seconds will be achieved in next experiment.

Journal Articles

Long pulse operation for JT-60U NBI system

Ebisawa, Noboru; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Seki, Norikazu*; Oga, Tokumichi; Ikeda, Yoshitaka

Heisei-16-Nendo Osaka Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 4 Pages, 2005/03

no abstracts in English

Journal Articles

Control of thermal load on the JT-60 NBI power supply system for 30 second operation

Oshima, Katsumi*; Honda, Atsushi; Okano, Fuminori; Usui, Katsutomi; Noto, Katsuya*; Muto, Hideki*; Kawai, Mikito; Oga, Tokumichi; Ikeda, Yoshitaka

Heisei-16-Nendo Osaka Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 4 Pages, 2005/03

no abstracts in English

Journal Articles

Design of renewal control system for NBI cryogenic plant

Kikuchi, Katsumi*; Akino, Noboru; Ikeda, Yoshitaka; Oga, Tokumichi; Oshima, Katsumi*; Okano, Fuminori; Takenouchi, Tadashi*; Tanai, Yutaka*; Honda, Atsushi

Heisei-16-Nendo Osaka Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 4 Pages, 2005/03

no abstracts in English

Journal Articles

Stabilization of beam power for long pulse operation on JT-60U negative-ion based NBI system

Honda, Atsushi; Kawai, Mikito; Okano, Fuminori; Oshima, Katsumi*; Numazawa, Susumu*; Oga, Tokumichi; Ikeda, Yoshitaka

Heisei-16-Nendo Osaka Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 4 Pages, 2005/03

no abstracts in English

Journal Articles

Present status of development on 500keV negative ion source

Yamamoto, Takumi; Oga, Tokumichi; Kawai, Mikito; Akino, Noboru; Kazawa, Minoru; Umeda, Naotaka

Heisei-16-Nen Denki Gakkai Zenkoku Taikai Koen Rombunshu, 219 Pages, 2004/00

In JAERI, 10 MW and 500 keV negative-ion based neutral beam injection (N-NBI) system for JT-60U was constructed in 1996, in order to study a plasma heating and current drive in high-density plasma by high-energy beam injection. Thereafter, improvement of beam performance has been carried out while N-NBI system was available for experiments on JT-60U. The maximum beam energy of 418 keV and the maximum injection power of 6.2 MW have been achieved with a hydrogen beam, so far. In addition, 10 seconds of injection pulse duration, which is the designed value, was attained at the injection power of 2.6MW. Further improvement is required for the performance to reach to the final targets. It was made it clear that the performance was limited by the withstanding voltage of acceleration and heat load on acceleration grids in the ion source.

Journal Articles

Progress of negative ion source improvement in N-NBI for JT-60U

Kawai, Mikito; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hanada, Masaya; Honda, Atsushi; Inoue, Takashi; Kazawa, Minoru; Kikuchi, Katsumi*; Kuriyama, Masaaki; et al.

Fusion Science and Technology, 44(2), p.508 - 512, 2003/09

 Times Cited Count:4 Percentile:32.68(Nuclear Science & Technology)

The negative ion source for negative ion based neutral beam injector(N-NBI) of JT-60U aims at generating a negative ion beam with 500 keV and 22A for 10s. The N-NBI system was completed in 1996, followed by starting the efforts to increase beam power and energy. (1)Spatial non-uniformity of the source plasma causes position-dependent divergence of a beamlet due to mis-matching of local beam perveance. A part of the divergent energetic beams is intercepted by the grids and resultantly produce the excessive heat load of the grids and/or induce the high voltage breakdown. So several techniques to take measures against and to correct the non-uniformity in these sources were implemented. (2)Correction of beamlet deflection by adjusting the electric field at the extraction grids. It improved the beam divergence and then decreased an excessive heat load of a beam limiter by more than 50 %. As a result, the maximum injection power 6.2MW and beam pulse duration 10 seconds were obtaind.

Journal Articles

Improvement of beam performance in the negative-ion based NBI system for JT-60U

Umeda, Naotaka; Grisham, L. R.*; Yamamoto, Takumi; Kuriyama, Masaaki; Kawai, Mikito; Oga, Tokumichi; Mogaki, Kazuhiko; Akino, Noboru; Yamazaki, Haruyuki*; Usui, Katsutomi; et al.

Nuclear Fusion, 43(7), p.522 - 526, 2003/07

 Times Cited Count:37 Percentile:74.66(Physics, Fluids & Plasmas)

The Negative-ion based Neutral Beam Injection System (N-NBI) for JT-60U has been operating for plasma heating and non-inductive current drive since 1996. The target is inject of neutral beam into plasma with beam energy 500 keV, injection power 10 MW, for 10 seconds. Until now pulse duration time was restricted up to 5.3 seconds because of larger heat load of port limiter. Recently from the measurement of beam profile at 3.5m downstream from the ion source, it was found that the outermost beamlets in each segment were deflected outward. It was caused by non-uniform electric field by grooves. By improving this, outermost beamlet deflection angle was decreased from 14 mrad to 4 mrad. In this result, 10 seconds injection, which is target parameter, has achieved at 355 keV, 2.6MW, while pulse length was restricted up to 5.3 seconds by larger heat load of port limiter.

Journal Articles

Operation and develoment on the positive-ion based neutral beam injection system for JT-60 and JT-60U

Kuriyama, Masaaki; Akino, Noboru; Ebisawa, Noboru; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Mogaki, Kazuhiko; Oga, Tokumichi; Ohara, Hiroshi; Umeda, Naotaka; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.424 - 434, 2002/09

 Times Cited Count:15 Percentile:69.46(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Operation and development on the 500-keV negative-ion-based neutral beam injection system for JT-60U

Kuriyama, Masaaki; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; Mogaki, Kazuhiko; Ohara, Yoshihiro; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.410 - 423, 2002/09

 Times Cited Count:48 Percentile:93.88(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Present status of the negative ion based neutral beam injector for JT-60U

Oga, Tokumichi; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; et al.

Review of Scientific Instruments, 73(2), p.1058 - 1060, 2002/02

 Times Cited Count:12 Percentile:56.93(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Improving the performance of a negative-ion based neutral beam injector for JT-60U

Yamamoto, Takumi; Umeda, Naotaka; Kuriyama, Masaaki; Lei, G.*; Grisham, L. R.*; Kawai, Mikito; Oga, Tokumichi; JT-60 NBI-Team

Journal of Plasma and Fusion Research SERIES, Vol.5, p.474 - 477, 2002/00

The performance of a 500keV negative-ion based neutral beam injection system for the JT-60U has been enhanced significantly. By improving the beam divergence, 10-second operation of beam injection has been attained. Small peaks were observed in the beam profile measured at the near field. These peaks are clearly resulted from the deflection of the beamlets due to an unwanted electric field. Correction of the deflection reduced the heat load on the limiter at the injection port by more than 50%. The Doppler shifted spectrum from the negative ion beam was measured, and then indicated that electron stripping of the negative ion beam occurs primarily inside the extraction grid, as expected from theoretical consideration. The electron stripping contributed to half of the heat load on the grounded grid.

JAEA Reports

Construction of negative-ion based NBI for JT-60U

Kawai, Mikito; Akino, Noboru; Ebisawa, Noboru; Honda, Atsushi; Ito, Takao; Kazawa, Minoru; Kuriyama, Masaaki; Mogaki, Kazuhiko; Oga, Tokumichi; Ohara, Hiroshi; et al.

JAERI-Tech 2001-073, 98 Pages, 2001/11

JAERI-Tech-2001-073.pdf:4.65MB

The world's first negative-ion based neutral beam injector(N-NBI) system has been developed for studies of non-inductive current drive and plasma core heating with high energy neutral beam injection in higher density plasma. Construction of the N-NBI system for JT-60U was completed in March 1996. The system is composed of a beamline with two ion souces, a set of ion source power supllies, control system and auxiliary sub-system such as cooling water, refrigeration and vaccum system. In July 2001, deuterium neutral beam injection of 400keV and 5.8MW into JT-60U plasma was achieved. In order to increase both beam power and energy we have to go on more improvement of the N-NBI.

Journal Articles

Study of increasing the beam power on the negative ion based neutral beam injector for JT-60U

Kuriyama, Masaaki; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; Kusaka, Makoto*; et al.

Fusion Engineering and Design, 56-57(Part.A), p.523 - 527, 2001/10

 Times Cited Count:5 Percentile:40.34(Nuclear Science & Technology)

no abstracts in English

75 (Records 1-20 displayed on this page)