@article{article,
  author = {S. Rode and C. Baumann and S. Brezinsek and A. Kirschner and H. A. Kumpulainen and L. Moser and R. A. Pitts and J. Romazanov and A. Terra and S. Wiesen and T. Wauters},
  title = {ERO2.0 study of impurity deposition on ITER diagnostic mirrors assuming different material mixes},
  abstract = {In ITER, diagnostic apertures are located in the Diagnostic First Wall (DFW) of the Equatorial and Upper Port Plugs (EPP, UPP). The apertures serve as entry points to mirror systems of optical diagnostics, such as the Visible and Infrared Wide Angle Viewing Systems. Impacting particle fluxes, e.g. energetic Charge-Exchange Neutral (CXN) hydrogen isotopes or impurities from e.g. sputtered wall material, can affect the quality of the mirror systems by deposition and erosion on the plasma-facing metallic mirrors, i.e. the First Mirrors (FMs). In this study, the particle fluxes into the diagnostic ports and apertures of the UPP and EPP cut-outs in the DFW of ITER were simulated with the Monte-Carlo plasma-wall interaction and transport code ERO2.0. The study presents results for the deposition of impurities on the FMs inside the DFWs and serves as predictive modelling as part of the ITER re-baselining activities with exchange of the first wall material from beryllium (Be) to tungsten (W). Three different material assumptions are assessed: (i) an infinitely boronized ITER representing the worst-case scenario fluxes into the ports from boron layers deposited on the First Wall by regular boronizations, (ii) a comparison to the originally planned material mix with Be First Wall and W divertor components, assuming complete coverage of the DFW by Be and (iii) a full-W first wall and divertor in ITER. The key findings of this study focusing on steady-state inter-ELM H-mode conditions in diverted magnetic configuration are favourable for the FM performance: the erosion and deposition on the FMs at the end of the currently envisaged ITER operational plasma time (~2200 h) are negligible in the centre of the FMs in both ports, featuring less than 10 nm deposition of impurities, and ~10nm erosion of the metallic mirror surface, presently made of molybdenum, in all cases. Sputtering in this recessed area is caused nearly exclusively by the CXN in all cases, which means that the assumed DFW material does not significantly affect the FM erosion. Concerning additional impurity deposition of material from entrance of the DFW onto the mirrors, the boronized ITER performs slightly better than a bare Be/W ITER. A pristine full-W ITER is expected to have the lowest first wall impurity deposition on the first mirror, showing nearly exclusively the effects of the impinging CXN on the DFW surfaces and mirrors themselves. A simplified assessment of the optical performance shows that even in the worst-case assumptions, the mirrors retain around 65\% of their initial specular reflectivity in the centre of the mirror surface, with the boron cases showing worse performance due to the significantly worse optical properties of boron compared to beryllium.},
  year = {2026},
  journal = {Nuclear Materials and Energy},
  volume = {46},
  pages = {102173},
  doi = {10.1016/j.nme.2026.102173},
  language = {eng},
}