The sputtering and transport of tungsten (W) impurity in the EAST tokamak have been investigated by the nonlinear magnetohydrodynamic code JOREK. The hybrid kinetic-fluid model in JOREK enables us to study the impacts of the Larmor gyration, sheath acceleration and, W sputtering energy and D+ impinging energy on the W sputtering and transport, which are generally simplified and ignored in fluid transport codes. The simulated W gross erosion flux exhibits a reasonable agreement with the measured data obtained through spectroscopy diagnostics on EAST. By means of the kinetic model in JOREK, it is indicated that the gyration and sheath effects can enhance the W redeposition probability on divertor targets by around three times compared to the fluid treatment. Moreover, the Thompson energy distribution for sputtered W particles has been attempted to survey the influence of the W sputtering energy on the W transport and redeposition, which shows a small discrepancy in the mean free path and redeposition probability of W particles compared to the case with a fixed sputtering energy. The detailed analysis of the W sputtering under the Maxwellian velocity distribution has been conducted, revealing significantly higher W erosion and leakage compared to the monoenergetic case. Eventually, the combined effects of the Larmor gyration, sheath acceleration, W sputtering energy and D+ impinging energy on W transport and redeposition behaviors have been investigated under varying plasma scenarios. It is found that the prompt redeposition of W particles plays a dominant role in the entire W redeposition compared to the long-range redeposition.
This paper investigates the sputtering and transport of tungsten impurities in the EAST tokamak using the JOREK code. It examines the effects of Larmor gyration, sheath acceleration, and tungsten sputtering energy on the tungsten erosion and redeposition, providing insights into the complex plasma-material interactions.