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

The design of the modification of JT-60U, JT-60SA has been optimized from the viewpoint of plasma performance, and operation regimes have been evaluated with the latest design. Upper and lower divertors with different geometries will be prepared for flexibility of the plasma shape, which will enable both low aspect ratio (A ~ 2.65) and ITER shape (A = 3.1) configurations. The beam lines of negative-ion neutral beam injection will be shifted downwards by ~0.6 m for the off-axis current drive (CD), in order to obtain a weak/reversed shear plasma, as well as having the capability of heating the central region. The feedback control coils along the openings in the stabilizing plate are found effective in suppressing the resistive wall mode and sustaining high βN close to the ideal wall limit. Sustainment of plasma current of 3–3.5 MA for 100 s will be possible in ELMy H-mode plasmas with moderate heating power, βN, and density within an available flux swing. It is also expected that higher βN, high-density ELMy H-mode plasmas will be maintained for 100 s with higher heating power. The expected regime of full CD operation has been extended with upgraded heating and CD power. Full CD operation for 100 s with reactor-relevant high values of normalized beta and bootstrap current fraction (Ip = 2.4 MA, βN = 4.3, fBS = 0.69, , HH98y2 = 1.3) is expected in a highly-shaped low-aspect-ratio configuration (A = 2.65).

[1]  T. W. Petrie,et al.  ELM energy scaling in DIII-D , 2002 .

[2]  A. Loarte,et al.  Study of Type III ELMs in JET , 2004 .

[3]  Shinji Tokuda,et al.  A new eigenvalue problem associated with the two-dimensional Newcomb equation without continuous spectra , 1999 .

[4]  P. B. Snyder,et al.  Pedestal performance dependence upon plasma shape in DIII-D , 2007 .

[5]  T. Fujita,et al.  Advanced tokamak research on long time scales in JT-60 Upgradea) , 2006 .

[6]  T. Oikawa,et al.  Electron cyclotron heating assisted startup in JT-60U , 2005 .

[7]  CurrentDrive,et al.  Chapter?8: Plasma operation and control , 1999 .

[8]  Gerald A. Navratil,et al.  Modeling of active control of external magnetohydrodynamic instabilities , 2001 .

[9]  L. L. Lao,et al.  Progress toward long-pulse high-performance Advanced Tokamak discharges on the DIII-D tokamak , 2001 .

[10]  Itpa H-mode Power Threshold Databas Takizuka.  Roles of aspect ratio, absolute B and effective Z of the H-mode power threshold in tokamaks of the ITPA database , 2004 .

[11]  Hiroshi Azechi,et al.  Design study of National Centralized Tokamak facility for the demonstration of steady state high-β plasma operation , 2005 .

[12]  Hiroshi Azechi,et al.  Overview of the National Centralized Tokamak programme , 2006 .

[13]  S. Jardin,et al.  Plasma Profile and Shape Optimization for the Advanced Tokamak Power Plant, ARIES-AT , 2001 .

[14]  L. Giannone,et al.  Regime identification in ASDEX Upgrade , 2004 .

[15]  C. Bathke,et al.  Physics basis for a reversed shear tokamak power plant , 1997 .

[16]  Y. Kamada,et al.  SlimCS—compact low aspect ratio DEMO reactor with reduced-size central solenoid , 2007 .

[17]  C. Gormezano,et al.  High performance tokamak operation regimes , 1999 .

[18]  R. S. Devoto,et al.  Numerical analysis of 2D MHD equilibrium with non-inductive plasma current in tokamaks , 1992 .

[19]  A. Polevoi,et al.  Overview of physics basis for ITER , 2003 .

[20]  F. Ryter,et al.  Density peaking, anomalous pinch, and collisionality in tokamak plasmas. , 2003, Physical review letters.

[21]  G. A. Navratil,et al.  Critical β analyses with ferromagnetic and plasma rotation effects and wall geometry for a high 𝛃 steady state tokamak , 2006 .

[22]  Akira Kohyama,et al.  Compact reversed shear tokamak reactor with a superheated steam cycle , 2000 .

[23]  F. Ryter,et al.  Theory-based modeling of particle transport in ASDEX Upgrade H-mode plasmas, density peaking, anomalous pinch and collisionality , 2003 .

[24]  Y. Nakamura,et al.  Design study of fusion DEMO plant at JAERI , 2006 .

[25]  L. Lao,et al.  Modification of high mode pedestal instabilities in the DIII-D tokamak , 2000 .

[26]  A. Kukushkin,et al.  Divertor modelling and extrapolation to reactor conditions , 2002 .