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 : hatano@ctg.u-toyama.ac.jp)

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.