Glow-Discharge Optical Emission Spectroscopy for Plasma ... · Introduction Reliable analysis of...
Transcript of Glow-Discharge Optical Emission Spectroscopy for Plasma ... · Introduction Reliable analysis of...
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.
Glow-Discharge Optical Emission Spectroscopy for
Plasma-Surface Interaction StudiesY. Hatano1*, N. Yoshida2, N. Futagami2, H. Harada2, T. Tokunaga2 and H. Nakamura3
1University of Toyama, 2Kyushu University, 3JAEA* (e-mail : [email protected])
What is GDOES?
Fig. 1 Principle of GDOES (a),
analysis procedure (b)-(e)
and example of analyzed
sample (f).
Emission spectrum is measured
by grating and photon detectors.
13 mm
(b) (c)
(d) (e)
(f)
Sputtered
atom
Emission
Ar or Ne ion
RF plasma
Optical
lens
O-ring
Sample
RF electrode
Sputtered
atom
Emission
Ar or Ne ion
RF plasma
Optical
lens
O-ring
Sample
RF electrode
Emission
Ar or Ne ion
RF plasma
Optical
lens
O-ring
Sample
RF electrode
(a)
Size of sputtering crater1 – 10 mm
Typical sputtering rate
25 nm/s for tungsten
Low energy, high flux incident
ions give minimum damage to
sample.
HORIBA Jobin Yvon GD-Profiler2 in Instrumental Analysis Lab., U. Toyama
396.00 396.05 396.10 396.15 396.20 396.25 396.300.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
D
Inte
nsi
ty (
arb
. u
nit
)
Wavelength (nm)
Hca. 70 pm
396.00 396.05 396.10 396.15 396.20 396.25 396.300.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
D
Inte
nsi
ty (
arb
. u
nit
)
Wavelength (nm)
Hca. 70 pm
0 200 400 600 8000
20
40
60
80
H,
D e
mis
sio
n (
arb
. u
nit
)
HD
O
Cr
Fe
Fe,
Cr,
O c
on
cen
tra
tio
n (
at.
%)
Depth (nm)
Isotopic Measurement of Hydrogen
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.
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.
Fig. 2 Emission spectrum from Zircaloy-2
oxidized first in H2O and then in D2O.
Fig. 3 Depth profiles of H and D in type 304
stainless steel oxidized in D2O for
144 h.
D2O, 144 h
He Measurement
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).
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:
He I (587.562 nm), Anode diameter: 10 mm
Ne plasma (1200 Pa, 80 W).
Summary 1: Profiles of H and D could be measured distinctly !
0 50 100 150 2000.0
0.1
0.2
0.3
0.4
0.5
He
/ W
Depth (nm)
Fig. 4 Retention curves of He by W.
5 keV
1 ×××× 1021 m-2 He at 8 keV
and room temperature.
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 !
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.