The development of a three-dimensional finite element method code for the heat flux analysis of tungsten monoblock divertor on EAST

摘要

The calculation of heat flux on the divertor is critical to study the characteristics of energy transport in controlled fusion plasma. Since 2014, the upper divertor of Experimental Advanced Superconducting Tokamak (EAST) has been upgraded into water-cooled W/Cu monoblock, and therefore the original two-dimensional(2D) heat calculation code does not apply to the heat flux calculation on the upper divertor due to the asymmetry toroidal geometry. Thus, it is urgent to develop a Three-dimension(3D) heat flux calculation code based on Finite Element Method(FEM) to determine the 2D heat flux distribution at the divertor surface in EAST. This paper presents a detailed design and development of this 3D FEM heat flux calculation method with the full consideration the monoblock geometry of the upper divertor. Based on the surface temperature captured from the IR camera, and the effect of a thin surface layer on the divertor, the heat transmission coefficient was determined in the solution of heat conduction equation. To benchmark this code, the calculation results are compared with the results using ANSYS software with the same conditions(constant temperature boundary and constant heat flux boundary). The comparison results show good agreements that the maximum fractional error between the two methods is less than 4 %. Finally, the characteristics of heat flux distribution on the divertor due to edge localized modes(ELMs) losses on EAST are also demonstrated.