The impact of impurity peaking factor on ion temperature promotion in EAST argon-seeded plasmas

Abstract This study investigates the impact of impurity peaking factor ( PF ) on turbulence and ion temperature ( T i ) in Experimental Advanced Superconducting Tokamak (EAST) argon-seeded plasmas. Through controlled impurity injection and comprehensive diagnostic analyses, the experiments demonstrate that both turbulence stabilization and T i enhancement are influenced not only by impurity concentration but also critically by PF . Specifically, impurity seeding induces a steep core impurity density gradient in the unfavorable toroidal field B t , leading to an 18.8% increase in core T i . In contrast, the core impurity density gradient is weaker in the favorable B t , resulting in ne g ligible changes in core T i . Simulation analyses further confirm that high PF suppresses ion temperature gradient (ITG) turbulence, reducing ion thermal diffusivity ( χ i ) and thereby facilitating T i enhancement. This work presents the first experimental evidence on EAST that PF -driven ITG stabilization leads to T i enhancement, offering valuable insights into impurity control strategies and plasma performance optimization for future fusion device.