Description
This study investigates micro-instabilities and turbulent transport in CFETR using the gyrokinetic code NLT, focusing on tritium fraction, temperature ratio, fast ions, and impurities. In the hybrid scenario, the ITG mode is most unstable at r=0.4a. Increasing the tritium fraction \varepsilon_T strongly suppresses ITG, with the maximum growth rate scaling as \frac{\gamma_{max,DT}}{\gamma_{max,D}}=\frac{2}{2+\varepsilon_T}. The growth rate peaks at a deuterium-tritium temperature ratio \tau_{DT}\approx ~1.5. Total ion energy flux is insensitive to \varepsilon_T, but particle fluxes reverse direction when \tau_{DT} exceeds 1.5. For \varepsilon_T=0.5 hybrid case, fast deuterium ions (concentration 0.15) suppress ITG but enhance TEM, while argon impurities (5e-3) stabilize both. Electromagnetic effects also stabilize these modes. Above a charge concentration threshold of 0.01, ITG growth decreases linearly with impurity/fast ion concentration. Density gradients significantly impact stability: a positive gradient for fast ions stabilizes ITG/TEM, while for argon it stabilizes ITG but destabilizes TEM. Nonlinear simulations show both species reduce D-T heat diffusivity. Fast ions suppress ITG primarily via dilution. Argon acts through both dilution and density gradient effects, with the latter becoming more important at larger positive gradients. In the steady-state scenario, the dominant instability shifts radially: the core (r~0.2a) is dominated by KBM, sensitive to ion temperature gradient and βe; this transitions to ITG/TEM outward, with ITG remaining dominant outside the ITB (r>0.6a). High-temperature fast ions (Tf /TD=15.7) stabilize core KBM via dilution. Argon stabilizes KBM through both dilution and density gradient effects. In the edge, low fast-ion concentration renders their effect on ITG negligible, while argon's stabilizing effect on ITG depends strongly on its concentration and density gradient, consistent with the hybrid scenario findings.