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Journal Articles

Design optimization for plasma performance and assessment of operation regimes in JT-60SA

Fujita, Takaaki; Tamai, Hiroshi; Matsukawa, Makoto; Kurita, Genichi; Bialek, J.*; Aiba, Nobuyuki; Tsuchiya, Katsuhiko; Sakurai, Shinji; Suzuki, Yutaka; Hamamatsu, Kiyotaka; et al.

Nuclear Fusion, 47(11), p.1512 - 1523, 2007/11

 Times Cited Count:23 Percentile:65.43(Physics, Fluids & Plasmas)

Design of modification of JT-60U, JT-60SA, has been optimized in viewpoint of plasma control, and operation regimes have been evaluated. Upper and lower divertors with different geometry are prepared for flexibility of plasma shape control. The beam lines of negative-ion NBI are shifted downward for off-axis current drive, in order to obtain a weak/reversed shear plasma. The feedback control coils along the port hole in the stabilizing plate are found effective to suppress the resistive wall mode (RWM) and sustain high $$beta$$$$_{rm N}$$ close to the ideal wall limit. The regime of full current drive operation has been extended with upgraded heating and current drive power. Full current drive operation for 100 s with reactor-relevant high values of normalized beta and bootstrap current fraction ($$I$$$$_{rm p}$$ = 2.4 MA, $$beta$$$$_{rm N}$$ = 4.4, $$f$$$$_{rm BS}$$ = 0.70, $$bar{n}$$$$_{rm e}$$/$$n$$$$_{rm GW}$$ = 0.86, H$$_{rm H98y2}$$ = 1.3) is expected in a highly-shaped low-aspect-ratio configuration ($$A$$ = 2.65). High $$beta$$$$_{rm N}$$, high-density ELMy H-mode is also expected.

Journal Articles

Progress in the ITER physics basis, 3; MHD stability, operational limits and disruptions

Hender, T. C.*; Wesley, J. C.*; Bialek, J.*; Bondeson, A.*; Boozer, A. H.*; Buttery, R. J.*; Garofalo, A.*; Goodman, T. P.*; Granetz, R. S.*; Gribov, Y.*; et al.

Nuclear Fusion, 47(6), p.S128 - S202, 2007/06

 Times Cited Count:759 Percentile:98.25(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Overview of the national centralized tokamak programme

Kikuchi, Mitsuru; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Takase, Yuichi*; Sakurai, Shinji; Kizu, Kaname; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; et al.

Nuclear Fusion, 46(3), p.S29 - S38, 2006/03

 Times Cited Count:13 Percentile:44.28(Physics, Fluids & Plasmas)

The National Centralized Tokamak (NCT) facility program is a domestic research program for advanced tokamak research to succeed JT-60U incorporating Japanese university accomplishments. The mission of NCT is to establish high beta steady-state operation for DEMO and to contribute to ITER. The machine flexibility and mobility is pursued in aspect ratio and shape controllability, feedback control of resistive wall modes, wide current and pressure profile control capability for the demonstration of the high-b steady state.

Journal Articles

Critical $$beta$$ analyses with ferromagnetic and plasma rotation effects and wall geometry for a high $$beta$$ steady state tokamak

Kurita, Genichi; Bialek, J.*; Tsuda, Takashi; Azumi, Masafumi*; Ishida, Shinichi; Navratil, G. A.*; Sakurai, Shinji; Tamai, Hiroshi; Matsukawa, Makoto; Ozeki, Takahisa; et al.

Nuclear Fusion, 46(2), p.383 - 390, 2006/02

 Times Cited Count:9 Percentile:33.28(Physics, Fluids & Plasmas)

It is shown that critical beta is decreased by ferromagnetic effect by about 8% for $$mu$$/$$mu$$$$_{0}$$$$sim$$2, $$mu$$ and $$mu$$$$_{0}$$ denoting the permeability of ferromagnetic wall and vacuum, respectively, for tokamak of aspect ratio 3. The existence of the stability window for resistive wall mode opened by both effects of the toroidal plasma rotation and the plasma dissipation, which was not observed for high aspect ratio tokamak, is found for tokamak of aspect ratio 3. The effect of ferromagnetism on them is also investigated. The critical beta analyses of NCT (National Centralized Tokamak) plasma using VALEN code are started with stabilizing plate and vacuum vessel geometry with finite resistivity, and the results for passive effect of stabilizing plate are obtained. The calculations including stabilizing effect of the vacuum-vessel and also active feedback control are also performed for present design of NCT plasma.

Journal Articles

Critical $$beta$$ analyses with ferromagnetic and plasma rotation effects and wall geometry for a high $$beta$$ steady state tokamak

Kurita, Genichi; Bialek, J.*; Tsuda, Takashi; Azumi, Masafumi; Ishida, Shinichi; Navratil, G. A.*; Sakurai, Shinji; Tamai, Hiroshi; Matsukawa, Makoto; Ozeki, Takahisa; et al.

IAEA-CN-116/FT/P7-7 (CD-ROM), 8 Pages, 2004/11

The critical beta is shown to be decreased by ferromagnetic effect by about 8 % for m/m0$$sim$$2, m and m0 denote the permeability of ferromagnetic wall and vacuum, respectively, for tokamak of aspect ratio 3. The existence of the stability window opened by both effects of the toroidal plasma rotation and the plasma dissipation, which was not observed for high aspect ratio tokamak, is found for tokamak of aspect ratio 3. The effect of ferromagnetism on them is also investigated. The critical beta analyses of NCT (National Centralized Tokamak) plasma using VALEN code are started with stabilizing plate and vacuum vessel geometry with finite resistivity, and the results for passive effect of stabilizing plate are obtained. The calculations including stabilizing effect of the vacuum-vessel and also active feedback control are also performed for present design of NCT plasma.

Oral presentation

Analyses and control of RWM in national centralized tokamak

Kurita, Genichi; Bialek, J.*; Navratil, G. A.*; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Suzuki, Takahiro; Sakurai, Shinji; Tsuda, Takashi; Ozeki, Takahisa; et al.

no journal, , 

no abstracts in English

Oral presentation

RWM analyses of JT-60SA and JT-60U tokamak plasmas

Kurita, Genichi; Bialek, J.*; Fujita, Takaaki; Tamai, Hiroshi; Matsukawa, Makoto; Matsunaga, Go; Takechi, Manabu; Tsuda, Takashi; Ozeki, Takahisa; Navratil, G. A.*; et al.

no journal, , 

JT-60SA is a tokamak device, being now designed at JAEA with collaboration of EU. One of the main purpose of JT-60SA is to realize the steady state plasma with high normallized beta values, 3.5$$sim$$5.5. Our previous analyses have shown that the critical normalized beta value was 3.8 with the effect of the stabilizing structure with finite resitivity and the active feedback control. The critical beta value is very low compared to the critical normalized beta of 5.5 in the case using ideal stabilizing structure, which results in very low C$$beta$$ value of 0.37 and bad efficiency of feedback control. To overcome these, we consider the new configuration of stabilizing structure and feedbacck control coil. The analyses are being carried out by VALEN code developed in Columbia University for new equiilibrium including transport analyses of JT-60SA plasma. We also present the results of analyses of experimental data of current driven and pressure driven RWM in JT-60U tokamak.

Oral presentation

RWM analyses of JT-60SA and JT-60U tokamak plasmas

Kurita, Genichi; Bialek, J.*; Fujita, Takaaki; Tamai, Hiroshi; Matsukawa, Makoto; Matsunaga, Go; Takechi, Manabu; Tsuda, Takashi; Ozeki, Takahisa; Navratil, G. A.*; et al.

no journal, , 

JT-60SA is a tokamak device, being now designed at JAEA with collaboration of EU. One of the main purpose of JT-60SA is to realize the steady state plasma with high normalized beta values, 3.5-5.5. Our previous analyses have shown that the critical normalized beta value was 3.8 with the effect of the stabilizing structure with finite resistivity and the active feedback control. The critical beta value is very low compared to the critical normalized beta of 5.5 in the case using ideal stabilizing structure, which makes the efficiency of feedback control low. To improve efficiency, we consider the new configuration of stabilizing structure and feedback control coil. The analyses are being carried out by VALEN code developed in Columbia University for new equilibrium including transport analyses of JT-60SA plasma. We also present the results of analyses of experimental data of current driven and pressure driven RWM in JT-60U tokamak.

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