Evaluating the effects of tungsten on CFETR phase I performance

Abstract

An integrated modeling workflow using OMFIT is constructed to evaluate the effects of tungsten (W) impurity on China Fusion Engineering Test Reactor (CFETR) performance. Self-consistent modeling of W core density profile, accounting for both turbulent and neoclassical transport contributions, is performed based on the steady-state scenario of CFETR phase I (Wan et al 2016 IAEA; Wan et al 2017 Nucl. Fusion 57 102009). It is found that the fusion performance degrades mildly with increasing W concentration. The main challenge arises in the sustainment of H-mode operation with significant W radiation. Assuming that the power threshold of H–L back transition is approximately the same as that of L–H transition, the W fraction at the plasma boundary is not allowed to exceed to stay in H-mode for CFETR phase I according to the scaling law proposed by Takizuka et al (2004 Plasma Phys. Control Fusion 46 A227–33). In addition, the tolerance of W concentration decreases with increasing pedestal density through a trade-off study of pedestal density and temperature. A future step is to connect the core simulation to W wall erosion modeling.