High fusion performance in Super H-mode experiments on Alcator C-Mod and DIII-D

Nuclear Fushion

article

P.B. Snyder¹  J.W. Hughes²  T.H. Osborne¹  C. Paz-Soldan¹  W.M. Solomon¹  M. Knolker³  D. Eldon¹  T. Evans¹  T. Golfinopoulos²  B.A. Grierson³  R.J. Groebner¹  A.E. Hubbard²  E. Kolemen³  B. LaBombard²  F.M. Laggner³  O. Meneghini¹  S. Mordijck⁴  T. Petrie¹  S. Scott³  H.Q. Wang¹  H.R. Wilson⁵  Y.B. Zhu⁷ 

[1] General Atomics;MIT Plasma Science and Fusion Center;Princeton Plasma Physics Laboratory, Princeton University, Princeton;College of William and Mary;York Plasma Institute, University of York;Culham Center for Fusion Energy, Culham Science Centre;University of California Irvine

关键词: pedestal;    tokamak;    fusion gain;    Super H Mode;    EPED;    DIII-D;    Alcator C-Mod;   

DOI  :  10.1088/1741-4326/ab235b

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

The 'Super H-Mode' regime is predicted to enable pedestal height and fusion performance substantially higher than standard H-Mode operation. This regime exists due to a bifurcation of the pedestal pressure, as a function of density, that is predicted by the EPED model to occur in strongly shaped plasmas above a critical pedestal density. Experiments on Alcator C-Mod and DIII-D have achieved access to the Super H-Mode (and Near Super H) regime, and obtained very high pedestal pressure, including the highest achieved on a tokamak ( p  _ped ~ 80 kPa) in C-Mod experiments operating near the ITER magnetic field. DIII-D Super H experiments have demonstrated strong performance, including the highest stored energy in the present configuration of DIII-D ( W~ 2.2–3.2 MJ), while utilizing only about half of the available heating power ( P _heat ~ 7–12 MW). These DIII-D experiments have obtained the highest value of peak fusion gain,Q _DT,equiv ~ 0.5, achieved on a medium scale ( R   <  2 m) tokamak. Sustained high performance operation ( β _N ~ 2.9, H₉₈ ~ 1.6) has been achieved utilizingn   =  3 magnetic perturbations for density and impurity control. Pedestal and global confinement has been maintained in the presence of deuterium and nitrogen gas puffing, which enables a more radiative divertor condition. A pair of simple performance metrics is developed to assess and compare regimes. Super H-Mode access is predicted for ITER and expected, based on both theoretical prediction and observed normalized performance, to allow ITER to achieve its goals ( Q   =  10) atI _p  <  15 MA, and to potentially enable more compact, cost effective pilot plant and reactor designs.

【 授权许可】

Unknown