Abstract
Experimental and modeling investigations of high βp scenarios on DIII-D and EAST tokamaks show advantages in high energy confinement, avoidance of n = 1 MHD, and core-edge integration with reduced heat flux, making this scenario an attractive option for China Fusion Engineering Test Reactor steady-state operation. Experiments show that plasmas with high confinement and high density can be achieved with neutral beam injection on DIII-D (βp ∼2.2, βN ∼3.5, fBS ∼50%, fGw ∼1.0, and H98y2 ∼1.5) and pure RF power on EAST (βP ∼2.0, βN ∼1.6, fBS ∼50%, fGw ∼0.8, and H98y2 > 1.3). By tailoring the current density profile, a q-profile with local (off-axis) negative shear is achieved, which yields improved confinement and MHD stability. Transport analysis and simulation suggest that the combination of a high density gradient and high Shafranov shift allows turbulence stabilization and higher confinement. Using on-axis Electron Cyclotron Heating injection, tungsten accumulation is avoided on EAST, and this is reproduced in modeling. Reduced heat flux (by > 40%) and maintenance of high core confinement is achieved with active feedback control of the radiated divertor, an important result for long pulse operation in tokamaks. The improved physics understanding and validated modeling tools are used to design a 1 GW steady-state scenario for CFETR.
Original language | English |
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Article number | 042506 |
Journal | Physics of Plasmas |
Volume | 28 |
Issue number | 4 |
DOIs | |
State | Published - Apr 1 2021 |
Externally published | Yes |
Funding
This work was supported by National MCF Energy R&D Program (2019YFE03040000 and 2019YFE03020004), National Natural Science Foundation of China under Grant (11975274 and 11975276), users with Excellence Program of Hefei Science Center CAS 2019HSC-UE013, Anhui Provincial Natural Science Foundation No. 2008085J04, and U.S. Department of Energy (DOE) DE-FC02-04ER54698.