LAUSR

Low-Z impurity injection is widely used for divertor detachment operation in present tokamaks, while the impurity effects on the main plasma is not fully understood yet. In this paper, the impurity effects on the ITG modes in tokamak edge plasmas is investigated based on Euler matrix eigenvalue method. The eigen-equations with multiple ion species is established from the fundamental gyro-kinetic theory, in which each ion species is treated equally. Efficient gyro-kinetic code is newly developed for numerical study, and the code’s availability to study quasi-linear ITG modes is demonstrated by comparing with existing results. At the pedestal top parameters in EAST high-βp Hmode plasmas, the ITG mode behavior is investigated in pure deuterium plasmas and with impurities. Impurities can induce destabilizing or stabilizing effect on ITG modes, determined by the impurity density scale length. Inwardly peaked impurity density profile tends to reduce the ITG growth rate. And the effect strength also increases with the impurity charge concentration. The effects of impurity species are also studied including boron, carbon, neon and argon. Numerical results show that the strength of destabilizing or stabilizing effect inverses with impurity ion charge at the same effective charge.