Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ishijima, Tatsuo
JAERI-Research 2000-015, p.94 - 0, 2000/03
no abstracts in English
Kubo, Hirotaka; Higashijima, Satoru; Takenaga, Hidenobu; Kumagai, Akira*; Shimizu, Katsuhiro; Sugie, Tatsuo; Suzuki, Shingo; Sakasai, Akira; Asakura, Nobuyuki
NIFS-PROC-44, p.65 - 68, 2000/01
no abstracts in English
Shimizu, Katsuhiro; Takizuka, Tomonori; Sakasai, Akira
Journal of Nuclear Materials, 241-243, p.167 - 181, 1997/00
Times Cited Count:55 Percentile:95.21(Materials Science, Multidisciplinary)no abstracts in English
Kubo, Hirotaka; Sugie, Tatsuo; Shimizu, Katsuhiro; Sakasai, Akira; Higashijima, Satoru; Koide, Yoshihiko; Asakura, Nobuyuki; Shimada, Michiya; JT-60 Team
UV and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas (Frontiers Science Series No. 15), 0, p.29 - 34, 1996/00
no abstracts in English
Hirayama, Toshio; Sugie, Tatsuo; Sakasai, Akira; Yoshino, Ryuji;
JAERI-M 91-169, 15 Pages, 1991/10
no abstracts in English
JAERI-M 8750, 92 Pages, 1980/03
no abstracts in English
;
JAERI-M 8420, 50 Pages, 1979/09
no abstracts in English
JAERI-M 6965, 24 Pages, 1977/02
no abstracts in English
Obrejan, K.; Idomura, Yasuhiro; Honda, Mitsuru*
no journal, ,
To analyze heavy impurity transport, the gyrokinetic full-f Eulerian code GT5D was extended with an implicit collision solver based on a multi-species linear Fokker-Plank collision operator. In the collision solver, a Krylov subspace method is applied to a collision operator, which is given as a convection diffusion operator in velocity space, and severe CFL conditions of heavy impurities are resolved. In addition, flux coordinates are newly applied to resolve magnetic field structures with less grids, and collisional transport simulations are dramatically accelerated. A collisional transport benchmark of tungsten was conducted to verify the accuracy of GT5D.
Obrejan, K.; Idomura, Yasuhiro; Honda, Mitsuru*
no journal, ,
The use of tungsten to coat divertors or other plasma facing components, inevitably leads to the pollution of the fusion plasma by heavy and highly charged (high-Z) impurities. This kind of neoclassical and turbulent transport of high-Z impurities is not yet fully understood. To study high-Z impurity transport, the gyrokinetic full-f Eulerian simulation code GT5D was upgraded with an implicit collision solver based on a multi-species linear Fokker-Plank collision operator. The commonly employed low order approximation of the standard neoclassical theory showed good agreement for low-Z impurities, but large differences were observed for high-Z impurities in the presence of temperature gradients. We tested an improved form of the neoclassical transport theory, that takes into account higher order flows to more accurately recover the friction coefficients in a high collisionality regime, showing good agreement with GT5D. An important consequence of this improved method is the weakening of thermal screening effect of bulk ions on impurity transport.
Obrejan, K.; Idomura, Yasuhiro; Honda, Mitsuru*
no journal, ,
The use of tungsten in plasma facing components inevitably leads to the pollution of the fusion plasma by heavy impurities and their accumulation at the core. Although heavy impurity transport has been estimated by the neoclassical transport theory, recent studies exhibited differences between global gyrokinetic simulations and the Hirshman-Sigmar (HS) moment approach, a commonly employed local theory. We performed a thorough benchmark for neoclassical particle transport of various impurities using the newly upgraded multi-species linear Fokker-Plank collision operator of our gyrokinetic full-f Eulerian simulation code GT5D. While good agreement was obtained in the case of flat temperature profiles, the dependence on the temperature gradient was found to be much weaker than the H-S theory in small machine sizes. Good agreement between GT5D and the H-S theory was recovered only for the case of large machine sizes, similar to ITER but beyond that of most current fusion devices.
Obrejan, K.; Idomura, Yasuhiro; Honda, Mitsuru*
no journal, ,
The use of tungsten in plasma facing components inevitably leads to the pollution of the fusion plasma by heavy impurities and their accumulation at the core, and this phenomenon is not yet fully understood. In this study, we performed a thorough comparison of the impurity particle fluxes between the global gyrokinetic full-f Eulerian code GT5D and local collisional transport theory called as the Hirshman-Sigmar moment approach. It is found that the simulation and the theory agree only in flat temperature profile cases or in large device sizes comparable to ITER. The cause of their discrepancy at the current device sizes is investigated in detail by comparing flows, which drive collisional impurity transport.