@article{oai:repo.qst.go.jp:00081854,
 author = {Kajita, S. and Hiroaki, Ogawa and Kitazawa, Sin-iti and Toshihiro, Oikawa and Veshchev, E. and Hiroaki, Ogawa and Kitazawa, Sin-iti and Toshihiro, Oikawa},
 journal = {Journal of Instrumentation},
 month = {Nov},
 note = {We investigated feasibility of an alignment method using first mirrors of the divertor impurity monitor (DIM) in ITER based on ray tracing analysis. A misalignment could occur between the divertor cassette and measurement system. It is shown that the misalignment can be compensated to some extent by rotating the first mirror. The maximum compensable misalignment and the required accuracy in the alignment are discussed. It is likely that the surface roughness of the first mirrors gradually increases during ITER operation. We investigated the required quality of the first mirror as focusing on the beam divergence using the ray tracing model. Moreover, to check the performance, helium plasma irradiation was performed on molybdenum mirror samples, and the beam divergence was measured using a laser and a detector. Based on the simulations and experiments, it is shown that the helium effect does not harm the performance of the mirror when the mirror temperature is less than 800 K.},
 title = {Performance of first mirrors for divertor impurity monitor in ITER: compensation of misalignment and effect of beam divergence},
 volume = {15},
 year = {2020}
}