TY - JOUR
T1 - Surface modification of tungsten mirrors due to low-energy helium plasma irradiation in the compact PWI simulator APSEDAS
AU - Sakamoto, M.
AU - Miyazaki, T.
AU - Higashizono, Y.
AU - Ogawa, K.
AU - Ozaki, K.
AU - Ashikawa, N.
AU - Tokitani, M.
AU - Shoji, T.
AU - Masuzaki, S.
AU - Tokunaga, K.
AU - Ohya, K.
AU - Sagara, A.
AU - Yoshida, N.
AU - Sato, K. N.
N1 - Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2009
Y1 - 2009
N2 - 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.
AB - 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.
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U2 - 10.1088/0031-8949/2009/T138/014043
DO - 10.1088/0031-8949/2009/T138/014043
M3 - Conference article
AN - SCOPUS:77953889895
VL - T138
JO - Physica Scripta
JF - Physica Scripta
SN - 0031-8949
M1 - 14043
T2 - 12th International Workshop on Plasma-Facing Materials and Components for Fusion Applications, PFMC-12
Y2 - 11 May 2009 through 14 May 2009
ER -