Evaluation of tungsten effect on CFETR phase I performance*

An integrated modeling workflow using OMFIT/TGYRO is constructed to evaluate Tungsten (W) impurity effects on China Fusion Engineering Test Reactor (CFETR) performance. Self-consistent modeling of W core density profile, accounting for both turbulence and neoclassical transport contribution, is performed based on the CFETR steady-state scenario developed by D.Zhao (ZhaoDeng, APS, 2016). It's found that the fusion performance degraded in a limited level with increasing W concentration. The main challenge arises in sustainment of H-mode with significant W radiation. Assuming the power threshold of H-L back transition is approximately the same as that of L-H transition; it is found that the W concentration is not allowed to exceed 3e-5 to stay in H-mode for CFETR phase I according to the scaling law found by Takizuka (Takizuka etc, Plasma Phys. Control Fusion, 2004). In addition, it's found that the tolerance of W concentration decreases with increasing pedestal density by trade-off study of pedestal density and temperature. A future step is to connect this requirement to W wall erosion modeling.