Study on the effect of EAST divertor geometric accuracy on heat load distribution

In the EAST experiment, the extent of damages of the divertor is different in toroidal direction. One of the reasons is uneven of heat load of toroidal distribution, which may be caused by geometric errors of the divertor surface. The EAST lower divertor is cooled by 8 toroidal active water-cooling branches, and calorimetric system estimates the heat load and its distribution by measuring the cooling water temperature difference and flow rate. The non-uniformity of the heat load of 8 branches is -3.5% -4.5%. Besides, using the Leica AT960 / AT401 laser tracker to measure the profile deviation of the upgraded lower divertor, the non-uniformity of the geometric accuracy is -15% -25%. Besides, it's found that the annular heat load distribution is positively correlated with the comprehensive deviation of the divertor surface. The correlation coefficient is about 15%, and at least seven of the eight divertor regions meet this characteristic.