Heat Transfer Simulation of A-Frame Assembly to Support Alcator C-Mod Outer Divertor Upgrade

To design the Alcator C-Mod outer divertor to operate at 600°C and determine its effect on the surrounding vessel and diagnostics, heat transfer analysis must be performed. This paper describes the analysis and the results of heat transfer simulations of the outer divertor tiles, tile-mounting plate, support structure, and current shunt. Using Comsol, commercial FEA software package, a 3D wedge model that exploits the cyclic symmetry of the divertor, is created. By adjusting the power level of each of the 7 heaters used to elevate and control the divertor temperature, a uniform poloidal temperature distribution is achieved and the power requirements for the heaters are determined. The temperature of each component in the assembly is calculated, and results are used for further design changes. Additionally, radiation simulation on thermal shields are presented, which is used as ambient temperature for the heat transfer of the A-frame assembly. Furthermore, a full model of the entire outer divertor ring is presented with its toroidal temperature distribution. Finally, thermal stress of the plate is analyzed besides an analytical calculation of the maximum allowable temperature difference.