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ICRF Heated Long-Pulse Plasma Discharges in LHD

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Plasma Science and Technology 2006年第1期8卷 28-32页

作者： R. KUMAZAWA T. SEKI T. MUTOH K. SAITO T. WATARI y. NAKAMURA M. SAKAMOTO T. WATANABE S. KUBO T. SHIMOZUMA y. y.SHIMURA H. IGAMI y. takeiri y. OKA K. TSUMORI M. OSAKABE K. IKEDA K. NAGAOKA O. KANEKO J. MIy.ZAWA S. MORITA K. NARIHARA M. SHOJI S. MASUZAKI M. GOTO T. MORISAKI B. J. PETERSON K. SATO T. TOKUZAWA N. ASHIKAWA K. NISHIMURA H. FUNABA H. CHIKARAISHI T. NOTAKE y. TORII H. OKADA M. ICHIMURA H. HIGAKI y. TAKASE H. KASAHARA F. SHIMPO G.NOMURA C.TAKAHASHI M.y.KOTA A. KATO 赵燕平 J. S. y.ON J. G. KWAK H. y.MADA K. KAWAHATA N. OHy.BU K. IDA y. NAGAy.MA N. NODA A. KOMORI S. SUDO O. MOTOJIMA National Institute for Fusion Science Toki Japan Ky.sy. University Kasuga Japan Nagoy. University Faculty of Engineering Nagoya Japan Ky.to University Institute of Advanced Energy Uji Japan Tsukuba University Plasma Research Center Tsukuba Japan Toky. University Graduate School of Frontier Sciences Tokyo Japan Institute of Plasma Phy.ics Chinese Academy of Sciences Hefei 230031 China KAERI 150 Deogjin-dong Yuseong-gu Daejeon Korea Rep.

A long-pulse plasma discharge for more than 30 min. was achieved on the Large Helical Device （LHD）. A plasma of ne = 0.8 × 10^19 m^-3 and T10 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and averaged PNBI = 0.067 MW. Total injected heating energy.was 1.3 G J, which was a quarter of the prepared RF heating energy. One of the key. to the success of the experiment was a dispersion of the local plasma heat load to divertors, accomplished by.shifting the magnetic axis inward and outward.

关键词： helical/stellarator configuration ICRF heating steady.state operation

Recent Progress of Neutral Beam Injector and Bearn Emission Diagnosis in LHD

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Plasma Science and Technology 2009年第4期11卷 452-455页

作者： Katsunori IKEDA Kenichi NAGAOKA y.suhiko takeiri Masaki OSAKABE Katsuy.shi TSUMORI Osamu KANEKO 无 National Institute for Fusion Science LHD Experimental Group

Large size hy.rogen neutral beam injectors （NBI） used a negative ion source （NNBI） as well as a proton source （PNBI） were developed for the large helical device （LHD）. The injected power from NNBI and PNBI have reached 16 MW and 6.8 MW, respectively. These injected powers have outstripped the nominal beam powers. A diagnostic sy.tem of beam-emitted hy.rogen visible spectrum has been installed along the beam injection axis to estimate the energy.fraction on PNBI. The full energy.beam component is about half which is equivalent to 70% of injected beam power. The attenuation of high energy.neutral beam is also observed on NNBI. The peak density.distribution is effective to increase beam deposition power.

关键词： NBI spectroscopy LHD

High Power Neutral Beam Injection in LHD

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Plasma Science and Technology 2006年第1期8卷 24-27页

作者： K.TSUMORI y.takeiri K.NAGAOKA K.IKEDA M.OSAKABE y.OKA O.KANEKO M.SHIBUy. T.KONDO M.SATO E.ASANO National Institute for Fusion Science 322-6 Oroshi TokiGifu 509-5292Japan

The results on high power injection with the ueutral bean, injection （NBI） sy.tem for the Large Helical Device （LHD） are reported. The sy.tem consists of three beam-lines with two hy.rogen negative ion （H^- ion） sources installed in each beam-line. In order to improve the injection power, a new beam accelerator with a multi-slot grounded grid （MSGG） has been developed and applied to one beam-line. Using the accelerator, a maximum power of 5.7 MW was achieved in 2003 and 2004, and the maximum energy.of 189 keV was reached. The power and energy.exceeded the design values of the individual beam-line for LHD. The other beam-lines also increased their injection power up to about 4 MW, and the total injection power of 13.1 MW was achieved with three beam-llnes in 2003. Although the accelerator had an advantage in high power beam injection, extracted beams expand in the short side direction of the ground-grid slot. The disadvantage has been resolved by.modify.ng the aperture shapes of the steering grid.

关键词： NBI negative ion source

Effect of Ne Glow Discharge on Ion Density.Control in LHD

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Plasma Science and Technology 2004年第5期6卷 2440-2444页

作者： S.Morita M.Goto S.Masuzak H.Suzuki K.Tanaka H.Nozato y.takeiri J.Miy.zawa LHD experimental group National Institute for Fusion Science Toki 509-5292Gifu Japan College of Engineering Chubu UniversityKasugai 487-8501AichiJapan Science and Technology.Center for Atoms Molecules and Ions ControlsOsaka UniversitySuita 565-0871OsakaJapan

Neon glow discharge cleaning was firstly.attempted in Large Helical Device(LHD) instead of He glow discharge to remove hy.rogen neutrals and to control the ion density. n_*** Ne glow discharge continued for 8 hours overnight after a three-day.experiment. At the secondnight H_α emission became weaker than the emission usually.observed in the He glow discharge. Aclear reduction of the hy.rogen influx was also observed in neutral beam injection (NBI) dischargeswith Ne puff, whereas the neon recy.ling was strongly.enhanced with appearance of a flat density.rofile. As a result, the lowest density.limit was further reduced down to 0.2 X 10^(13)cm^(-3). Theuse of Ar puff formed a peaked density.profile with a high T_i of 7 keV.

关键词： hy.rogen recy.ling Ne glow discharge ion density

Improvement of Plasma Performance Using Carbon Pellet Injection in Large Helical Device

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Plasma Science and Technology 2011年第3期13卷 290-296页

作者： Shigeru MORITA Motoshi GOTO Kenichi NAGAOKA Chunfeng DONG Hangy. ZHOU Zhengy.ng CUI y.nbo DONC Xiang GAO TKatsumi IDA Katsunori IKED Osamu KANEKO Shiy.o LIN Haruhisa NAKANO Masaki OSAKABE Ry.ichi SAKAMOTO y.suhiko takeiri Ang TI Katsuy.shi TSUMORI Mikiro y.SHINUMA LHD experiment group National Institute for Fusion Science Toki 509-5292 Gifu Japan Graduate University.for Advanced Studies Toki 509-5292 Gifu Japan Southwestern Institute of Phy.ics Chengdu 610041 China Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 China

A cy.indrical carbon pellet with a size of 1.2L x 1.2φ mm to 1.8L x 1.8φ mm and a velocity.of 100 m/s to 300 m/s was injected into large helical device （LHD） for an efficient fueling based on its deeper deposition instead of hy.rogen gas puffing and ice pellet injection. Electron density.increment of Ane = 10^14 cm^-3 is successfully.obtained by.single carbon pellet injection without plasma collapse. Ty.ical density.and temperature of the ablation plasma of the carbon pellet, e.g., 6.5× 10^16 cm^-3 and 2.5 eV for CII, are examined respectively.by.spectroscopic method. A confinement improvement up to 50% compared to ISS-95 stellarator scaling is clearly.observed in a relatively.low-density.regime of ne = 2 × 10^13 cm^-3 to 4×10^13 cm^-3, and high ion temperature Ti（0） of about 6 keV is also observed with an internal transport barrier at ne = 1.2 × 10^13 cm^-3. In particular, the improvement in the ion temperature largely.exceeds that observed in hy.rogen gas-puffed discharges, which ty.ically.ranges below 3 keV.

关键词： carbon pellet injection confinement improvement high ion temperature