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Journal Articles

Development of cold isostatic pressing graphite module for a heat-resistant lower hybrid current drive antenna

Maebara, Sunao; Goniche, M.*; Kazarian, F.*; Seki, Masami; Ikeda, Yoshitaka; Imai, Tsuyoshi*; Beaumont, B.*

Review of Scientific Instruments, 76(5), p.053501_1 - 053501_7, 2005/05

 Times Cited Count:1 Percentile:10.49(Instruments & Instrumentation)

Development of a plasma facing module using Cold Isostatic Pressing Graphite (CIPG) had been done for a heat-resistant LHCD antenna. A thin stainless film (10$$mu$$m), molybdenum film (10$$mu$$m) and copper film (50$$mu$$m) are laid to overlap each other on the CIPG materials, the CIPG surfaces were successfully coated with copper layer by diffusion bonding method. This module has four waveguides and a water cooling channel, the length is 206 mm. High power long pulse operation was successfully achieved up to 250 kW (125 MW/m$$^{2}$$)/700s. The module has been successfully tested at a RF power density which is equivalent, in terms of RF electric field (5kV/cm), to the one proposed for the LHCD antenna of ITER-FEAT. The outgassing rate of the copper-coated CIPG is estimated to be 3.2-5.1$$times$$10$$^{-6}$$ Pa.m$$^{3}$$/s.m$$^{2}$$ at 100$$^{circ}$$C, it is assessed that a pumping system is not required to evacuate the pressure in the LHCD antenna.

Journal Articles

Current profile control and application to advanced tokamak/steady state plasma operations by lower hybrid waves

Ide, Shunsuke

Purazuma, Kaku Yugo Gakkai-Shi, 81(3), p.167 - 170, 2005/03

Non-inductive current drive (CD) by radio-frquency waves in the lower hybrid range of frequency (LHRF) is one of most powerful scheme to drive a plasma current and control the current profile of a tokamak plasma externally. This paper reviews recent achievement of CD by LHRF (LHCD) in tokamak experiments with special emphasis on steady state tokamak operation and profile control in an advanced tokamak.

Journal Articles

Profile control and plasma start-up by RF waves towards advanced tokamak operation in JT-60U

Takase, Yuichi*; JT-60 Team

AIP Conference Proceedings 694, p.235 - 242, 2003/05

A central electron temperature of 23 keV was obtained by EC wave injection. A highly localized current density profile was obtained by central ECCD, indicating an upper limit on the diffusion coefficient for resonant electrons of $$1{rm m^{2}/s}$$. The experimentally obtained current drive figure of merit was lower than theoretical prediction, possibly because of the negative loop voltage induced by overdrive. A comparison of HFS and LFS off-axis ECCD confirmed the theoretically expected trapped particle effect on the current drive efficiency. Offaxis LHCD was used to broaden the qmin radius and the ITB foot radius. N-NBCD was used to shrink the current hole radius. An integrated scenario consisting of (1) a novel plasma start-up method using RF plasma production and induction by vertical field and shaping coils, (2) a noninductive ramp-up stage, and (3) a transition to a high-density, bootstrap-dominated, highconfinement plasma, without the use of the OH solenoid, has been demonstrated. The plasma created by this technique had both internal and edge transport barriers, with $$beta_{rm p}=3.6$$($$epsilonbeta_{rm p}=1$$), $$beta_{rm N}=1.6$$, $$H_{rm H98y2}=1.6$$ and $$f_{rm BS}geq90%$$ at $$I_{rm p}=0.6$$MA and $$n_{rm e}=0.5n_{rm GW}$$.

Journal Articles

Combined non-inductive current drive in a high confinement reversed magnetic shear plasma at high normalized density in JT-60U

Ide, Shunsuke; Fujita, Takaaki; Suzuki, Takahiro; Hatae, Takaki; Naito, Osamu; Kamada, Yutaka; Seki, Masami

Plasma Physics and Controlled Fusion, 44(11), p.L63 - L69, 2002/11

 Times Cited Count:25 Percentile:69.35(Physics, Fluids & Plasmas)

Non-inductive full current drive (CD) in a reversed magnetic shear plasma (RS) with high energy confinement of 1.4 times the H-mode scaling at 82% of the Greenwald density has been achieved simultaneously for the first time in a tokamak; these results were obtained in the JT-60U tokamak. The full-CD state was realized by a combination of waves in the lower hybrid range of frequency and neutral beam injection together with high bootstrap current fraction ($$f_{rm bs}$$) of 62% to the total plasma current. The combination has demonstrated for the first time active current profile modification in a high $$f_{rm bs}$$ RS plasma both in the core and in peripheral regions.

Journal Articles

Noninductive current drive and steady-state operation in JT-60U

Ushigusa, Kenkichi; Ide, Shunsuke; Oikawa, Toshihiro; Suzuki, Takahiro; Kamada, Yutaka; Fujita, Takaaki; Ikeda, Yoshitaka; Naito, Osamu; Matsuoka, Mamoru*; Kondoh, Takashi; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.255 - 277, 2002/09

 Times Cited Count:6 Percentile:3.03(Nuclear Science & Technology)

Studies on non-inductive current drive and development of an integrated steady-state high performance operation in JT-60 are reviewed. Experiments on lower hybrid current drive in JT-60 haven shown a large non-inductive current up to 3.5MA, high current drive efficiency of 3.6x1019m-2A/W. Basic studies on LH waves in JT-60 have contributed to understand current drive physics. Significant progress in neutral beam current drive has been made in JT-60 by testing the performance of negative ion based NBI (N-NBI). The CD efficiency of ~1.5x1019m-2A /W, and N-NB driven current of ~1MA have been demonstrated in N-NBCD. Strongly localized driven current by electron cyclotron current drive was identified with a fundamental O-mode scheme. Efficiency of 0.5x1019m-2A/W and EC driven current of 0.2MA were achieved and suppression of neo-classical tearing mode was demonstrated. Based on these developments, two integrated steady-state operation scenarios were developed in JT-60, which are reversed magnetic shear (R/S) plasmas and high bp ELMy H-mode. In these operation regimes, discharges have been sustained near the steady-state current profile under full non-inductive current drive. High performance plasmas with a high nDotETio and at high normalized density were also produced under fully non-inductive condition in high bp ELMy H-mode and R/S mode.

JAEA Reports

Study of lower hybrid current drive system in tokamak fusion devices

Maebara, Sunao

JAERI-Research 2000-061, 104 Pages, 2001/01

JAERI-Research-2000-061.pdf:9.71MB

no abstracts in English

Journal Articles

Formation of internal transport barriers and its impact on the JT-60U plasmas

Ide, Shunsuke; JT-60 Team

Journal of Plasma and Fusion Research SERIES, Vol.4, p.99 - 105, 2001/00

no abstracts in English

Journal Articles

LHCD current profile control experiments towards steady state improved confinement on JT-60U

Ide, Shunsuke; Naito, Osamu; Oikawa, Toshihiro; Fujita, Takaaki; Kondoh, Takashi; Seki, Masami; Ushigusa, Kenkichi; JT-60 Team

Nuclear Fusion, 40(3Y), p.445 - 449, 2000/03

 Times Cited Count:49 Percentile:80.87(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Lower hybrid current drive in tokamak plasmas

Ushigusa, Kenkichi

JAERI 1339, 77 Pages, 1999/03

JAERI-1339.pdf:3.4MB

no abstracts in English

Journal Articles

Development of plasma facing component for LHCD antenna

Maebara, Sunao; Seki, Masami; ; ; Suganuma, Kazuaki; ; Imai, Tsuyoshi; Suzuki, Yasuo*; *; *; et al.

Fusion Engineering and Design, 39-40, p.355 - 361, 1998/00

 Times Cited Count:5 Percentile:45.37(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Development of a power divider in the $$H$$ plane using posts in a rectangular waveguide for the next generation lower hybrid current drive antenna

Seki, Masami; Maebara, Sunao; ; Ikeda, Yoshitaka; Imai, Tsuyoshi; Hirokawa, Jiro*; Arai, Hiroyuki*

Fusion Engineering and Design, 36(2-3), p.281 - 287, 1997/05

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Modification of electron density profile during lower hybrid current drive in JT-60U

Ide, Shunsuke; Nagashima, Keisuke; Naito, Osamu

Purazuma, Kaku Yugo Gakkai-Shi, 73(1), p.112 - 121, 1997/01

no abstracts in English

Journal Articles

Development of a power divider in the H plane using posts in a rectangular waveguide for the next generation lower hybrid current drive antenna

Seki, Masami; Maebara, Sunao; *; Ikeda, Yoshitaka; Imai, Tsuyoshi; *; *

Fusion Engineering and Design, 36(2-3), p.281 - 287, 1997/00

no abstracts in English

Journal Articles

Report on the 16th IAEA fusion energy conference

Ida, Katsumi*; Okano, Kunihiko*; Ogawa, Yuichi*; Kamada, Yutaka; Kimura, Haruyuki; Nishihara, Katsunobu*; Fujisawa, Akihide*; Yagi, Masatoshi*; Iio, Shunji*

Purazuma, Kaku Yugo Gakkai-Shi, 72(12), p.1417 - 1423, 1996/12

no abstracts in English

Journal Articles

Application of LHCD for sustainment and control of a reversed magnetic shear plasmas in JT-60U

Ide, Shunsuke; Naito, Osamu; Fujita, Takaaki; Oikawa, Toshihiro; Seki, Masami; JT-60 Team

IAEA-CN-64/E-3, 10 Pages, 1996/10

no abstracts in English

JAEA Reports

Development of a new lower hybrid antenna module using a poloidal power divider

Maebara, Sunao; Seki, Masami; Suganuma, Kazuaki; Imai, Tsuyoshi; Goniche, M.*; P.Bibet*; S.Berio*; J.Brossaud*; Rey, G.*; G.Tonon*

JAERI-Research 96-036, 82 Pages, 1996/07

JAERI-Research-96-036.pdf:3.08MB

no abstracts in English

JAEA Reports

Performance test of lower hybrid waveguide under long/high-RF power transmission

Seki, Masami; Obara, Kenjiro; Maebara, Sunao; Ikeda, Yoshitaka; Imai, Tsuyoshi; Nagashima, Takashi; Goniche, M.*; J.Brossaud*; C.Barral*; G.Berger-By*; et al.

JAERI-Research 96-025, 55 Pages, 1996/06

JAERI-Research-96-025.pdf:2.06MB

no abstracts in English

Journal Articles

Development of a new lower hybrid antenna module using a poloidal power divider

Maebara, Sunao; Seki, Masami; Suganuma, Kazuaki; Imai, Tsuyoshi; Goniche, M.*; Ph.Bibet*; S.Berio*; J.Brossaud*; Rey, G.*; G.Tonon*

Fusion Technology 1996, 0, p.637 - 640, 1996/00

no abstracts in English

Journal Articles

Response of lower hybrid wave driven current profile on wave launching position

Ide, Shunsuke; Naito, Osamu; Kondoh, Takashi; Ikeda, Yoshitaka; Ushigusa, Kenkichi

Nuclear Fusion, 36(8), p.1057 - 1061, 1996/00

 Times Cited Count:4 Percentile:20.51(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Sustainment and modification of reversed magnetic shear by LHCD on JT-60U

Ide, Shunsuke; Fujita, Takaaki; Naito, Osamu; Seki, Masami

Plasma Physics and Controlled Fusion, 38(10), p.1645 - 1652, 1996/00

 Times Cited Count:52 Percentile:96.15(Physics, Fluids & Plasmas)

no abstracts in English

35 (Records 1-20 displayed on this page)