The decrease in tungsten (W) content with the higher ion cyclotron resonance heating (ICRH) power is observed and explained for the first time in a high power injection (Pinj > 10 MW), high performance (βN ∼ 2, βP ∼ 2.8, ne/nGW ∼ 80%, fBS ∼ 60%) H-mode discharge on experimental advanced superconducting tokamak. Unlike the previous phenomenon of electron cyclotron resonance heating core W control (Shi et al 2022 Nucl. Fusion62 066031), there is a slight change in the background plasma temperature when higher ICRH is applied, but the toroidal rotational velocity decreases by ∼10 km s−1 . Under this condition, the intensity of W unresolved transition array spectral structure in the region of 45–70 Ǻ (which is composed of W27+-W45+ line emissions) and W44+ density through spectroscopy in the Extreme Ultraviolet region decreases markedly. In addition, the poloidal asymmetry of radiation distribution from the tomographic inversions of Soft x-ray emission is reduced obviously. Theoretical modeling results indicate that the reduction in toroidal rotation leads to less W poloidal asymmetry and neoclassical pinch, which is more efficient in alleviating the core W accumulation than the improvement of isotropic hydrogen (H) minority temperature. The effects of isotropic and anisotropic H minority from ICRH on W transport are compared in the simulation lastly.
This paper reports the first observation of a decrease in tungsten (W) content with higher ion cyclotron resonance heating (ICRH) power in a high-performance H-mode discharge on the Experimental Advanced Superconducting Tokamak (EAST). The reduction in toroidal rotation leads to less W poloidal asymmetry and neoclassical pinch, which is more efficient in alleviating core W accumulation than the improvement of isotropic hydrogen minority temperature.