1Department of Modern Physics, University of Science and Technology of China, Hefei 230026 2Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 3University of Chinese Academy of Sciences, Beijing 100049 4College of Mechanical and Power Engineering, China Three Gorges University, Yichang 443002 5Songshan Lake Materials Laboratory, Dongguan 523808
Abstract：Microturbulence excited by ion temperature gradient (ITG)-dominant and trapped electron mode (TEM)-dominant instabilities is compared in the fusion plasmas using gyrokinetic simulations based on the realistic equilibrium data from DIII–D discharges. Collisions make a difference between two plasmas and give rise to similar results to those found in previous research experiments [Chin. Phys. Lett. 35 (2018) 105201]. The mode structures and frequency spectrum of the most unstable modes characterized by the ITG-dominant and TEM-dominant instabilities are excited in the lower and higher $T_{\rm e}$ plasmas in the linear simulations. In the nonlinear simulations, contour plots of the perturbed potential are shown in the saturated stage, with the radial correlation lengths being microscopic on the order of the ion thermal gyroradius $\rho_{\rm i}$ in both the ITG and the TEM microturbulences. The dominant mode wavelengths of the perturbed potential increase when evolving from linear to nonlinear stages in both simulations, with the fluctuation energy spreading from the linearly dominant modes to the nonlinearly dominant modes. The radial correlation lengths are about 4$\rho_{\rm i}$ and the electron density fluctuation intensities are about 0.85% in the nonlinear saturated stage, which are in agreement with the experimental results.
Dimit A M, Bateman G, Beer M A, Cohen B I, Dorl, W, Hammett G W, Kim C, Kinsey J E, Kotschenreuther M, Kritz A H, Lao L L, Mandrekas J, Nevins W M, Parker S E, Redd A J, Shumaker D E, Sydora R and Weiland J 2000 Phys. Plasmas7 969
Pace D C, Austin M E, Bass E M, Budny R V, Heidbrink W W, Hillesheim J C, Holcomb C T, Gorelenkova M, Grierson B A, McCune D C, McKee G R, Muscatello C M, Park J M, Petty C C, Rhodes T L, Staebler G M, Suzuki T, Van Zeel, M A, Waltz R E, Wang G, White A E, Yan Z, Yuan X and Zhu Y B 2013 Phys. Plasmas20 056108
2019, Vol. 36 
