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

Abstract

Abstract This study investigates the impact of impurity peaking factor (PF) on turbulence and ion temperature (Ti) 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 Ti 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 unfavourable toroidal field Bt, leading to an 18.8% increase in core Ti. In contrast, the core impurity density gradient is weaker in the favourable Bt, resulting in negligible changes in core Ti. Simulation analyses further confirm that high PF suppresses ion temperature gradient (ITG) turbulence, reducing ion thermal diffusivity (χi) and thereby facilitating Ti enhancement. This work presents the first experimental evidence on EAST that PF-driven ITG stabilization leads to Ti enhancement, offering valuable insights into impurity control strategies and plasma performance optimization for future fusion device.

Affiliated Institutions

• Chinese Academy of Sciences CN
• Hefei Institutes of Physical Science CN
• West Anhui University CN

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