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Journal Articles

Simulation study of power load with impurity seeding in advanced divertor "short super-X divertor" for a tokamak reactor

Asakura, Nobuyuki; Hoshino, Kazuo; Shimizu, Katsuhiro; Shinya, Kichiro*; Uto, Hiroyasu; Tokunaga, Shinsuke; Tobita, Kenji; Ono, Noriyasu*

Journal of Nuclear Materials, 463, p.1238 - 1242, 2015/08

 Times Cited Count:11 Percentile:67.6(Materials Science, Multidisciplinary)

Arrangements of interlink divertor coils and divertor geometries for short super-X was proposed as the Demo advanced divertor design. Performance of plasma detachment under the large heat flux was investigated to optimize the divertor design, using SONIC simulation with Ar impurity seeding, where Pout = 500 MW, ne = 7$$times$$10$$^{19}$$ m$$^{-3}$$ at the core-edge boundary and the same diffusion coefficients for ITER simulation. Effects on the plasma temperature and density distributions were compared to the conventional divertor. The first run results with the same radiation power fraction of 0.92 in the conventional divertor showed that full detached plasma is produced, the maximum radiation region was maintained upstream the divertor target, and both the plasma heat load plus radiation load at the target was reduced to 10 MWmm$$^{-2}$$ level. Simulation for the lower radiation power fractions of 0.8-0.9 was also performed, and physics issues of the short super-X divertor are discussed.

Journal Articles

Investigation of advanced divertor magnetic configuration for DEMO tokamak reactor

Asakura, Nobuyuki; Shinya, Kichiro*; Tobita, Kenji; Hoshino, Kazuo; Shimizu, Katsuhiro; Uto, Hiroyasu; Someya, Yoji; Nakamura, Makoto; Ono, Noriyasu*; Kobayashi, Masahiro*; et al.

Fusion Science and Technology, 63(1T), p.70 - 75, 2013/05

no abstracts in English

Journal Articles

Investigation of advanced divertor magnetic configuration for Demo tokamak reactor

Asakura, Nobuyuki; Shinya, Kichiro*; Tobita, Kenji; Hoshino, Kazuo; Shimizu, Katsuhiro; Uto, Hiroyasu; Someya, Yoji; Nakamura, Makoto; Ono, Noriyasu*; Kobayashi, Masahiro*; et al.

Fusion Science and Technology, 63(1T), p.70 - 75, 2013/05

 Times Cited Count:13 Percentile:69.84(Nuclear Science & Technology)

Design study of poloidal field coil (PFC) locations and current distribution for the advanced divertor in the Demo tokamak reactor was presented. Concept of the super-X divertor (SXD) for Demo reactor has an outer divertor leg longer than the conventional divertor, and it extends outboard to increase both the target wetted area and connection length to the outer target ($$L_{//}$$). Equilibrium calculation code, TOSCA, was developed by introducing two parameters, i.e. super-X null radius ($$R_{SX}$$) and a ratio of the poloidal flux at the super-X null to that at the separatrix ($$f_{SX}$$). Some SXD magnetic configurations with minimal number of PFCs located outside toroidal field coil (TFC) were Demonstrated. Locations of the divertor target were also investigated. It was found that the flux expansion can be increased up to 4-10 depending on the target location and $$f_{SX}$$, and that SXD has an advantage to increase $$L_{//}$$ with $$f_{SX}$$. Thus, the divertor plasma temperature is expected to decrease at the same upstream plasma density. On the other hand, large currents for the divertor PFCs were necessary. Other arrangements of PFCs such as (1) larger $$R_{SX}$$ and (2) inside TFC, can reduce the PFC currents.

Journal Articles

Simulation of VDE under intervention of vertical stability control and vertical electromagnetic force on the ITER vacuum vessel

Miyamoto, Seiji; Sugihara, Masayoshi*; Shinya, Kichiro*; Nakamura, Yukiharu*; Toshimitsu, Shinichi*; Lukash, V. E.*; Khayrutdinov, R. R.*; Sugie, Tatsuo; Kusama, Yoshinori; Yoshino, Ryuji*

Fusion Engineering and Design, 87(11), p.1816 - 1827, 2012/11

 Times Cited Count:14 Percentile:71.39(Nuclear Science & Technology)

Journal Articles

Concept of core and divertor plasma for fusion DEMO plant at JAERI

Sato, Masayasu; Sakurai, Shinji; Nishio, Satoshi; Tobita, Kenji; Inoue, Takashi; Nakamura, Yukiharu; Shinya, Kichiro*; Fujieda, Hirobumi*; DEMO Plant Design Team

Fusion Engineering and Design, 81(8-14), p.1277 - 1284, 2006/02

 Times Cited Count:14 Percentile:68.21(Nuclear Science & Technology)

no abstracts in English

Oral presentation

DINA analysis on effect of vertical position control on vertical force during VDE

Miyamoto, Seiji; Sugihara, Masayoshi*; Shinya, Kichiro*; Nakamura, Yukiharu*; Toshimitsu, Shinichi; Sugie, Tatsuo; Kusama, Yoshinori; Yoshino, Ryuji

no journal, , 

When Plasma Control System (PCS) generates wrong signal to the PF coils and in-vessel vertical stabilization (VS) coils, it could be happen that the vertical force somewhat larger than presently specified could be generated. Example is that though plasma moves downward, but PCS erroneously recognizes it is moving upward. Then PF coils start to generate the field pattern that tends to push plasma further downward and resultantly the force could be larger than the present specification, in which it is evaluated with the assumption that control system (PF coils) does nothing (i.e., short-circuited.) In fact, in the existing machines, this is the worst case. The DINA code is used to analyze the vertical force, which has been updated to incorporate the recent design change of the vacuum vessel and in-vessel VS coils. In the presentation, analysis of VS effect on the vertical force is discussed using the updated DINA code.

Oral presentation

Investigation of advanced divertor magnetic configurations and coil arrangements for demo tokamak reactor

Asakura, Nobuyuki; Shinya, Kichiro*; Hoshino, Kazuo; Tobita, Kenji; Shimizu, Katsuhiro; Uto, Hiroyasu; Someya, Yoji; Nakamura, Makoto; Sakamoto, Yoshiteru

no journal, , 

Design study of poloidal field coil (PFC) locations and current distribution for the advanced divertor in the Demo tokamak reactor was presented. Concept of the super-X divertor (SXD) for Demo reactor has an extra magnetic null in the outer divertor leg in order to increase both the target wetted area and connection length to the outer target ($$L_{//}$$). Equilibrium calculation code, TOSCA, was developed by introducing two parameters, i.e. super-X null location ($$R_{SX}$$, $$Z_{SX}$$) and a ratio of the poloidal flux at the super-X null to that at the separatrix ($$f_{SX}$$). SXD magnetic configurations with minimal number of PFCs located inside and outside toroidal field coil (TFC) were demonstrated. Locations of the divertor target were also investigated. It was found that SXD has an advantage to increase $$L_{//}$$ by 40-60% with $$f_{SX}$$, while increase in the flux expansion on the target is small (less than 40%). On the other hand, large currents for the divertor PFCs were required for the case of outside TFC, thus inter-TFC design is a practical solution. Magnetic configurations and arrangement of the divertor PFCs for a snowflake divertor were also demonstrated.

Oral presentation

Investigation of physics and engineering issues in advanced divertor design for tokamak Demo reactor

Asakura, Nobuyuki; Shinya, Kichiro*; Hoshino, Kazuo; Uto, Hiroyasu; Someya, Yoji; Tokunaga, Shinsuke; Tobita, Kenji; Nakamura, Makoto; Sakamoto, Yoshiteru; Ono, Noriyasu*

no journal, , 

no abstracts in English

Oral presentation

Investigation of advanced divertor, short super-X divertor, for demo tokamak reactor

Asakura, Nobuyuki; Hoshino, Kazuo; Uto, Hiroyasu; Someya, Yoji; Shimizu, Katsuhiro; Shinya, Kichiro*; Tokunaga, Shinsuke; Tobita, Kenji; Ono, Noriyasu*

no journal, , 

no abstracts in English

Oral presentation

Physics and engineering studies of the advanced divertor for a fusion reactor

Asakura, Nobuyuki; Hoshino, Kazuo; Uto, Hiroyasu; Shinya, Kichiro*; Tokunaga, Shinsuke; Shimizu, Katsuhiro; Someya, Yoji; Tobita, Kenji; Ono, Noriyasu*

no journal, , 

A short super-X divertor is proposed as a new option for fusion divertor, where field line length from the divertor null to the outer target (L//div) was largely increased (more than two times) in a similar size of conventional divertor. Physics and engineering design studies have progressed. Minimal number of the divertor coils (1 or 2) were installed inside the toroidal field coil (TFC), i.e. interlink-winding (interlink). Arrangement of the poloidal field coils (PFCs) and their currents were determined, taking into account of the engineering design such as vacuum vessel and the neutron shield structures, and maintenance scenario of the divertor and blankets. Divertor plasma simulation showed that large radiation region is produced between the super-X null and the target, and the plasma temperature becomes low (1-2 eV) both at the inner and outer divertors, i.e. fully detached plasma was obtained efficiently.

Oral presentation

Conceptual design study of an advenaced divertor, short super-X divertor

Asakura, Nobuyuki; Hoshino, Kazuo; Uto, Hiroyasu; Shinya, Kichiro*; Shimizu, Katsuhiro; Tokunaga, Shinsuke; Someya, Yoji; Tobita, Kenji; Ono, Noriyasu*

no journal, , 

no abstracts in English

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