Progress in extending high poloidal beta scenarios on DIII-D towards a steady-state fusion reactor and impact of energetic particles
[1];
[2];
[1];
[3];
[1];
[1];
[1];
[4];
[1];
[1];
[2];
[1]
more »
- Chinese Academy of Sciences (CAS), Hefei (China). Inst. of Plasma Physics
- General Atomics, San Diego, CA (United States)
- Univ. Carlos III de Madrid (Spain)
- Shenzhen Univ. (China). Advanced Energy Research Center
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Wisconsin, Madison, WI (United States)
- Univ. of California, Los Angeles, CA (United States)
- Oak Ridge Associated Univ., Oak Ridge, TN (United States)
To prepare for steady-state operation of future fusion reactors (e.g. the International Thermonuclear Experimental Reactor and China Fusion Engineering Test Reactor (CFETR)), experiments on DIII-D have extended the high poloidal beta (βP) scenario to reactor-relevant edge safety factor q95 ~ 6.0, while maintaining a large-radius internal transport barrier (ITB) using negative magnetic shear. Excellent energy confinement quality (H98y2 > 1.5) is sustained at high normalized beta (βN ~ 3.5). This high-performance ITB state with Greenwald density fraction near 100% and qmin ≥ 3 is achieved with toroidal plasma rotation Vtor ~ 0 at ρ ≥ 0.6. This is a key result for reactors expected to have low Vtor. At high βP (≥1.9), large Shafranov shift can stabilize turbulence leading to a high confinement state with a low pedestal and an ITB. At lower βP (<1.9), negative magnetic shear in the plasma core contributes to turbulence suppression and can compensate for reduced Shafranov shift to continue to access a large-radius ITB and excellent confinement with low Vtor, consistent with the results of gyrofluid transport simulations. These high-βP cases are characterized by weak/no Alfvén eigenmodes (a.e.) and classical fast-ion transport. At high density, the fast-ion deceleration time decreases and Δβfast is lower; these reduce a.e. drive. The reverse-shear Alfvén eigenmodes are weaker or stable because the negative magnetic shear region is located at higher radius, away from the peaked fast-ion profile. Resistive wall modes can be a limitation at simultaneous high βN, low internal inductance, and low rotation. Analysis suggests that additional off-axis external current drive could provide a more stable path at reduced q95. Based on a DIII-D high-βP plasma with large-radius ITB, two scenarios are proposed for CFETR Q = 5 steady-state operation with ~1 GW fusion power: a lower-$${l_i}{\text{ }}$$ ($${l_i}$$ ~ 0.66) and a higher-$${l_i}$$ ($${l_i}$$ ~ 0.75) case. Using a Landau closure model, multiple energetic particle (EP) effects on the a.e. stability are analyzed modifying the growth rate of the a.e.s triggered by the neutral-beam-injection EPs and alpha particles, although the stabilizing/destabilizing effect is weak for the cases analyzed. The stabilizing effects of the combined EP species β, energy, and density profile in CFETR need further investigation.
- Research Organization:
- General Atomics, San Diego, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Univ. of Wisconsin, Madison, WI (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of California, Los Angeles, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES); National Natural Science Foundation of China (NSFC); Anhui Provincial Natural Science Foundation
- Grant/Contract Number:
- FC02-04ER54698; AC52-07NA27344; FG02-08ER54999; AC05-00OR22725; FG02-08ER54984; 11975276; 2008085J04; AC52- 07NA27344; AC05- 00OR22725
- OSTI ID:
- 1666382
- Alternate ID(s):
- OSTI ID: 1664598; OSTI ID: 1797656; OSTI ID: 1798020
- Report Number(s):
- LLNL-JRNL-812779; TRN: US2203669
- Journal Information:
- Nuclear Fusion, Vol. 60, Issue 12; ISSN 0029-5515
- Publisher:
- IOP ScienceCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Joint DIII-D/EAST research on the development of a high poloidal beta scenario for the steady state missions of ITER and CFETR
Validation of Alfvén Eigenmode simulations on DIII-D and Projection for CFETR scenario