Surface modification of tungsten mirrors due to low-energy helium plasma irradiation in the compact PWI simulator APSEDAS

M. Sakamoto, T. Miyazaki, Y. Higashizono, K. Ogawa, K. Ozaki, N. Ashikawa, M. Tokitani, T. Shoji, S. Masuzaki, K. Tokunaga, K. Ohya, A. Sagara, N. Yoshida, K. N. Sato

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6 Citations (Scopus)

Abstract

Surface modification of a polycrystalline tungsten (W) mirror due to low-energy helium plasma irradiation has been studied in the compact plasma-wall interaction (PWI) simulator APSEDAS. Many fine irregularities of a few μm are generated on the W surface at Ts∼1400 K due to He bubble formation. On the other hand, a distinctive change in the surface morphology cannot be seen from the SEM micrograph on a W mirror exposed at T s<710 K. In both samples, the optical reflectivity with the incident angle θ=5° decreases more at shorter wavelength. From in situ measurement of the optical reflectivity with θ=75°, it is found that the optical reflectivity at λ∼555 nm of the low Ts exposure increased by ∼6% and decreased to the original level at a fluence of ∼3×1024 He+ m-2, and then increased again by ∼6% with the fluence up to ∼1.6×1026 He+ m-2. Calculations using a model of the multiple reflection in the modification region suggest that the thickness of the modification layer of the low Ts sample exceeds 70 nm.

Original languageEnglish
Article number14043
JournalPhysica Scripta T
VolumeT138
DOIs
Publication statusPublished - Dec 1 2009
Event12th International Workshop on Plasma-Facing Materials and Components for Fusion Applications, PFMC-12 - Julich, Germany
Duration: May 11 2009May 14 2009

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Mathematical Physics
  • Condensed Matter Physics

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    Sakamoto, M., Miyazaki, T., Higashizono, Y., Ogawa, K., Ozaki, K., Ashikawa, N., Tokitani, M., Shoji, T., Masuzaki, S., Tokunaga, K., Ohya, K., Sagara, A., Yoshida, N., & Sato, K. N. (2009). Surface modification of tungsten mirrors due to low-energy helium plasma irradiation in the compact PWI simulator APSEDAS. Physica Scripta T, T138, [14043]. https://doi.org/10.1088/0031-8949/2009/T138/014043