25aD49P
ヘリウム照射による低放射化フェライト鋼表面形状および組成変化
Surface modifications by helium bombardments in F82H and EUROFER
芦川直子1,2、杉山一慶3、A. Manhard3, M. Balden3, W. Jacob3、N. Ashikawa, K. Sugiyama3, A. Manhard3, M. Balden3, W. Jacob3
核融合研1、総研大2、マックスプランク・プラズマ物理研究所3
NIFS1、SOKENDAI12、IPP3
cm2 and then an erosion rate by helium irradiation ishigher than that after deuterium irradiation.
2D implantation : 1E24 D/m , 450K, 100V bias
Proton yield [Counts / C]

Reduced Activation Ferritic/Martensitic (RAFM)
steels, such as F82H and EUROFER, are candidate
materials for fusion DEMO reactor. To understand bulk
fuel retention and tritium inventories of plasma-facing
materials in DEMO, analyses of samples exposed todeuterium plasmas are essential. In this study, RAFM
steel samples are exposed to low energy deuterium
plasmas and the effects of surface modifications on
deuterium retention is elucidated.
RAFM steels, F82H (8Cr-2W) and EUROFER(9Cr-1W), are bombarded with steady-state deuterium
plasmas under conditions relevant to the first wall
environment using the PlaQ facility [1]. The surface
temperature of the samples during plasma exposure wasmeasured by thermocouples and an infrared camera. It
was set at 450 K. Target steels were exposed to helium
pre-irradiation applied a DC-bias voltage of 200V anddeuterium plasma bombardment applied a DC-bias
voltage of 100V. Applied deuterium and helium fluences
are 1 x 1024 D/m2 and of the order of 1024 He/m2,respectively. After the plasma exposures the samples
were analyzed with nuclear reaction analysis (NRA),
microbalance, Rutherford backscattering spectroscopy(RBS), scanning electron microscopy (SEM), X-ray
photoelectron spectroscopy (XPS).
Deuterium retention in the steels determined by
NRA is shown in Fig.1. NRA was done using D (He3, p)
4
He reaction at different energies, 690 keV, 1200 keV,
1800 keV, 2400 keV, 3200 keV and 4000 keV,respectively. Amounts of deuterium retention are of theorder of 1018 to 1019 D/m2 at the near top surface region
using an energy of 690 keV. Target samples with helium
pre-irradiation show higher deuterium retentions tocompare with without helium pre-irradiations. Thedifference between F82H and EUROFER is almost
negligible.
Figure 2 shows surface morphologies analyzed bySEM. After deuterium plasma bombardment, a smoothplane shown. From microbalance measurement, weightloss of 10 g per 1 cm2 was observed. But a surface on
the target after helium pre-irradiation shows pin-holder
like un-uniform structures as shown in Fig.2 (b). A
weight loss after helium irradiation is about 60 g per 1

25
F82H 224 Pre He-irr.
Eurofer 9 Pre He-irr.
F82H 204
Eurofer 120151050500

1000

15002000325003000

3500

40004500

He energy [keV]

Figure 1 Deuterium retentions in F82H andEUROFER targets exposed to helium
pre-irradiation
anddeuterium-plasma
bombardments in the Pla-Q dacility. Target
temperatures are 450 K.

(a)

(b)
1m

1m

Figure 2 Surface morphologies of F82H
measured by SEM. (a) deuterium
bombardment and (b) helium pre-irradiationand deuterium bombardment.

This work is supported by NIFS budget UFFF028,
KEMF058 and SOKENDAI Young Researcher Overseas
Visit Program.
1) A. Manhard, et al., Plasma Sources Sci. Technol.

(2011) 20 015010.