Speaker
Yoshiteru Sakamoto
(Department of Fusion Power Systems)
Description
Recent DEMO physics study has focused on several issues raised from the JA Model 2014 concept. The concept is characterized by a fusion power of ~1.5 GW and a major radius of 8.5 m based on the technical assessments of divertor heat removal capability, overall tritium breeding ratio TBR > 1.05, full inductive ramp-up of plasma current, and so on. A problem is compatibility between divertor detachment and operational density due to the low Greenwald density limit. Increase in a plasma elongation and decrease in the major radius are essential for increase of the Greenwald density limit. Regarding the plasma elongation, the effect of conducting shells on vertical stability has been investigated by considering the actual structures of in-vessel components and vacuum vessel compatible with maintenance scheme. The 3D eddy-current analysis indicates that a double-loop type shell contribute to improve the plasma elongation from 1.65 to 1.72. Regarding the major radius, the effect of ECH on the saving of CS flux consumption has been investigated. The result indicates that the CS-flux saving of ~30 Wb by the EC power of ~30 MW can contribute to reduce the major radius to ~8.25 m. Both results of higher plasma elongation and smaller major radius can increase the Greenwald density limit by over 10%. It should be noted that increasing the plasma elongation significantly reduces a requirement of energy confinement enhancement factor on H-mode scaling from 1.31 to 1.19. Furthermore, divertor plasma simulation at low density of 1.8x101919m-3-3 at the separatrix shows that full detachment at the inner divertor and partial detachment at the outer divertor are produced with high radiation fraction of 0.7-0.8 by Ar impurity seeding.
Co-authors
Akinobu Matsuyama
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Haruhiko Takase
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Hiroyasu Utoh
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Kazuo Hoshino
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Kenji Tobita
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Nobuhiko Hayashi
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Nobuyuki Aiba
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Nobuyuki Asakura
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Shinsuke Tokunaga
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Shunsuke Ide
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Takuma Wakatsuki
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Yoshiteru Sakamoto
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
Yuki Homma
(Department of Fusion Power Systems, Japan Atomic Energy Agency, Aomori, Japan)
