Analysis of Assembly Accuracy for the Upgraded EAST Lower Divertor

The divertor is the key plasma-facing components of tokamak device for exhausting the heat load. The uneven distribution of heat load is the inherent characteristic of the divertor, it may be caused by the geometric configuration of the divertor and physical experiments. The improvement of assembly accuracy of divertor can alleviate the uneven distribution of heat load. So, the assembly accuracy analysis is important content in the upgrading of the Experimental Advanced Superconducting Tokamak (EAST) lower divertor. According to the physical experiments and modeling of the scrape-off layer, the parent requirements of profile accuracy of the divertor is <= +/- 0.5 mm, in which the EAST device center is the assembly datum. A +/- 0.3 mm from assembly ring references respect to EAST datums. And CETOL 3-D software is used for assembly accuracy analysis and tolerance allocation of divertor module to meet the above requirements. Then, the parts processing and divertor assembly are completed according to the design accuracy, and Leica AT960/AT401 laser tracker are used for assembly accuracy measurement (acceptance). The results show that more than 85% of the measuring points meet accuracy requirements (+/- 0.5 mm). In addition, a feasible assembly accuracy control method, repair, and assembly method is introduced to improve the assembly accuracy.