26aC01
重水素照射および重水素・ヘリウム同時照射時における低放射化フェライト鋼 F82H の表面形態の変化とスパッタリング率、水素同位体吸蔵に関する研究
The study of surface morphology, sputtering yield and deuterium retention in reduced
activation ferritic martensitic steel (F82H) under simultaneous deuterium and helium irradiation
薬師寺高輝、Lee Heun Tae、大宅諒、伊庭野健造、上田良夫
K.Yakushiji, H.T. Lee, M.Oya, K.Ibano, Y. Ueda

大阪大学大学院工学研究科
Graduate School of Engineering, Osaka University
1. Introduction	  Reduced Activation Ferritic Martensitic (RAFM)
steels have been developed and studied in several
countries, and they are presently the leadingcandidates as structural material in a fusion reactor.
To minimize the cost and complexity of building
and operating a fusion reactor, it has been suggested
that bare RAFM steels be used without any armor
materials for the first wall in a fusion reactor. This
will lead to direct implantation of hydrogenisotopes and helium impurities in the near surface,
and therefore hydrogen isotope retention behavior
in RAFM steels in the presence of helium needs to
be clarified. The effects of simultaneous irradiationof hydrogen isotopes and He in F82H have so far
not been examined in any detail. In this study, wecompare surface morphology, sputtering
yield and D retention behavior in F82H under
D-only and simultaneous D+He irradiation cases, toexamine the effect of He.
2. Experimental	  F82H samples used in this study were cut from
“IEA-heat t7” developed/procured by JapaneseAtomic Energy Agency. The sample dimensions
used in this study was 10×10×1 mm3. D-only
irradiation experiments and simultaneous D+He
irradiation experiments were performed using thehigh flux ion beam test device [1] (HiFIT) at OsakaUniversity, with 1 keV extraction voltage. Theirradiation experiments were performed at thefollowing temperature: 500 - 818 K. The irradiation
fluence was kept constant at 1×1024 D/m2. In
simultaneous D+He irradiation experiments, He
impurity % in the ion beam was estimated to be~0.5 %. Sputtering yield was estimated from massloss measurements before and after irradiation
experiments. Surface morphology change wasobserved with SEM. D and He retention in F82H
samples was determined by thermal desorption
spectroscopy (TDS) following ion irradiation
experiments.

3. Results	  At T ＞ 750 K sputtering yield increases withtemperature for both D-only and D+He irradiation
experiment. However the sputtering yield for
simultaneous D+He irradiation was systematicallyhigher correspondly, from SEM images significant
surface morphology change occurred at T ＞ 750
K. A systematic reduction in D retention due tosimultaneous D+He irradiation was observed asshown in Fig.1. There appeared to be a monotonic
increase in D retention with increasing temperature.
As for He retention, a maximum retention amount wasobserved from sample irradiated at 625 K. Atirradiation temperature greater than 625 K, amonotonic decrease in the He retention was observed.
It was clear that He results in a systematic decrease in
D retention. However D and He retention did not obey
similar temperature dependency.

Fig.1 Deuterium retention in F82H determinedfrom TDS as function of sample irradiation
temperature
References[1] Ueda Y et al 2002 Fusion Enginnering andDesign 61 255