Document 6516450

Glow-Discharge Optical Emission Spectroscopy for
Plasma-Surface Interaction Studies
Y.
1*
Hatano ,
1University
N.
2
Yoshida ,
of Toyama,
N.
2
Futagami ,
2Kyushu
H.
University,
2
Harada ,
3JAEA*
T.
2
Tokunaga
3
Nakamura
and H.
(e-mail : hatano@ctg.u-toyama.ac.jp)
Introduction
Reliable analysis of plasma-facing materials (PFMs) is indispensable to understand plasma-surface interactions (PSIs).
Glow-discharge optical emission spectroscopy (GDOES) is a technique to measure depth profiles of constituent elements in
a solid sample by detecting emissions from atoms accommodated in plasma by sputtering. The benefits of this technique are:
(1) PFMs used in fusion devices can be analyzed without modification (no ultra-high vacuum, large sample is acceptable),
(2) high depth resolution (a few nanometers), and (3) very quick measurements (several minutes)
In PSI studies, we need to measure depth profiles of H, D, T and He. In the present study, the abilities of GEOES for (1) isotopic
measurements of hydrogen and (2) detection of He have been examined.
What is GDOES?
(a)
Low energy, high flux incident
ions give minimum damage to
sample.
(f)
Optical
lens
Ar or Ne ion
Emission spectrum is measured
by grating and photon detectors.
(c)
(b)
Sample
RF plasma
13 mm
Emission
(d)
RF electrode
Fig. 1 Principle of GDOES (a),
analysis procedure (b)-(e)
and example of analyzed
sample (f).
(e)
Size of sputtering crater
1 – 10 mm
Typical sputtering rate
25 nm/s for tungsten
Sputtered
atom
O-ring
Depth profiles of H and D were analyzed by
adjusting
optics
arrangements
under
conventional plasma conditions (600 Pa Ar,
35 W, anode diameter 4 mm).
H and D were detected distinctly, and profiles at
oxide-metal
interface
were
successfully
measured. GDOES allows profile measurements
of hydrogen isotopes at interface between
dissimilar materials such as deposited layer and
PFMs. This type of measurement is difficult with
SIMS due to difference in secondary ion yields.
6.0
5.5
5.0
ca. 70 pm
4.5
H
4.0
3.5
3.0
2.5
2.0
1.5
D
1.0
0.5
0.0
396.00 396.05 396.10 396.15 396.20 396.25 396.30
80
Fe
60
40
D2O, 144 h
O
Cr
20
D
H
0
0
200
400
600
Depth (nm)
Wavelength (nm)
Fig. 2 Emission spectrum from Zircaloy-2
oxidized first in H2O and then in D2O.
H, D emission (arb. unit)
Various kinds of alloys (F82H reduced activation
ferritic steel, stainless steels, Zircaloy-2, etc.)
were oxidized in H2O and/or D2O at around
300 oC for various period of time.
Intensity (arb. unit)
Isotopic Measurement of Hydrogen
Fe, Cr, O concentration (at.%)
HORIBA Jobin Yvon GD-Profiler2 in Instrumental Analysis Lab., U. Toyama
800
Fig. 3 Depth profiles of H and D in type 304
stainless steel oxidized in D2O for
144 h.
Summary 1: Profiles of H and D could be measured distinctly !
He Measurement
5 keV
Measurement of He with GDOES is relatively
difficult because energy for He excitation (> 20 eV)
is high compared with the first ionization potential
of Ar (15.8 eV). Hence, we employed high power,
high pressure Ne plasma to detect He because of
higher ionization potential of Ne (21.6 eV).
He I (587.562 nm), Anode diameter: 10 mm
Ne plasma (1200 Pa, 80 W).
Fig. 4 Retention curves of He by W.
Fig. 5 Depth profile of He in W and
TEM image with the same
depth scale.
Summary 2:Profiles of He was successfully measured with Ne plasma !
1 × 1021 m-2 He at 8 keV
and room temperature.
0.4
He / W
The depth profile of He implanted into tungsten up
to fluence of 3×1021 m-2 at 8 keV and room
temperature was measured under the following
conditions:
0.5
0.3
0.2
0.1
0.0
0
50
100
150
Depth (nm)
200
Acknowledgements The authors would like to express their sincere thanks to Mr. T. Nakamura and Mr. A. Fujimoto of HORIBA Co. for their valuable advices. This study was
supported by Bilateral Collaborative Research Program of National Institute for Fusion Science, Japan.