Image quality as a possible method of in situ monitoring the in-vessel mirrors
The plasma facing mirrors (FM) in ITER will be subjected to sputtering and / or contamination with the rates depending on mirror locations. The result of influence of both these factors will be reduce of mirror reflectance (R) and worsen the quality of transmitted image (IQ). This implies that con...
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| Zitieren: | Image quality as a possible method of in situ monitoring the in-vessel mirrors / V.G. Konovalov, M.N. Makhov, A.N. Shapoval, N. Ashikawa, S. Masuzaki, A. Sagara, D.I. Naidenkova, I.V. Ryzhkov, A.F. Shtan’, S.I. Solodovchenko, V.S. Voitsenya // Вопросы атомной науки и техники. — 2006. — № 6. — С. 244-246. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-823542015-05-29T03:01:56Z Image quality as a possible method of in situ monitoring the in-vessel mirrors Konovalov, V.G. Makhov, M.N. Shapoval, A.N. Ashikawa, N. Masuzaki, S. Sagara, A. Naidenkova, D.I. Ryzhkov, I.V. Shtan, A.F. Solodovchenko, S.I. Voitsenya, V.S. Plasma diagnostics The plasma facing mirrors (FM) in ITER will be subjected to sputtering and / or contamination with the rates depending on mirror locations. The result of influence of both these factors will be reduce of mirror reflectance (R) and worsen the quality of transmitted image (IQ). This implies that control of the mirror quality in- situ is an actual problem, and this work is an attempt to approach to its solution. The method suggested for evaluation of IQ was applied to mirrors exposed in LHD, TRIAM-1M, TS and in the DSM-2 stand (IPP NSC KIPT). 2006 Article Image quality as a possible method of in situ monitoring the in-vessel mirrors / V.G. Konovalov, M.N. Makhov, A.N. Shapoval, N. Ashikawa, S. Masuzaki, A. Sagara, D.I. Naidenkova, I.V. Ryzhkov, A.F. Shtan’, S.I. Solodovchenko, V.S. Voitsenya // Вопросы атомной науки и техники. — 2006. — № 6. — С. 244-246. — Бібліогр.: 3 назв. — англ. PACS: 52.40.Hf ; 78.68.+m; 79.20.Rf http://dspace.nbuv.gov.ua/handle/123456789/82354 en Вопросы атомной науки и техники |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
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Plasma diagnostics Plasma diagnostics |
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Plasma diagnostics Plasma diagnostics Konovalov, V.G. Makhov, M.N. Shapoval, A.N. Ashikawa, N. Masuzaki, S. Sagara, A. Naidenkova, D.I. Ryzhkov, I.V. Shtan, A.F. Solodovchenko, S.I. Voitsenya, V.S. Image quality as a possible method of in situ monitoring the in-vessel mirrors Вопросы атомной науки и техники |
| description |
The plasma facing mirrors (FM) in ITER will be subjected to sputtering and / or contamination with the rates
depending on mirror locations. The result of influence of both these factors will be reduce of mirror reflectance (R) and
worsen the quality of transmitted image (IQ). This implies that control of the mirror quality in- situ is an actual
problem, and this work is an attempt to approach to its solution. The method suggested for evaluation of IQ was applied
to mirrors exposed in LHD, TRIAM-1M, TS and in the DSM-2 stand (IPP NSC KIPT). |
| format |
Article |
| author |
Konovalov, V.G. Makhov, M.N. Shapoval, A.N. Ashikawa, N. Masuzaki, S. Sagara, A. Naidenkova, D.I. Ryzhkov, I.V. Shtan, A.F. Solodovchenko, S.I. Voitsenya, V.S. |
| author_facet |
Konovalov, V.G. Makhov, M.N. Shapoval, A.N. Ashikawa, N. Masuzaki, S. Sagara, A. Naidenkova, D.I. Ryzhkov, I.V. Shtan, A.F. Solodovchenko, S.I. Voitsenya, V.S. |
| author_sort |
Konovalov, V.G. |
| title |
Image quality as a possible method of in situ monitoring the in-vessel mirrors |
| title_short |
Image quality as a possible method of in situ monitoring the in-vessel mirrors |
| title_full |
Image quality as a possible method of in situ monitoring the in-vessel mirrors |
| title_fullStr |
Image quality as a possible method of in situ monitoring the in-vessel mirrors |
| title_full_unstemmed |
Image quality as a possible method of in situ monitoring the in-vessel mirrors |
| title_sort |
image quality as a possible method of in situ monitoring the in-vessel mirrors |
| publishDate |
2006 |
| topic_facet |
Plasma diagnostics |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/82354 |
| citation_txt |
Image quality as a possible method of in situ monitoring the in-vessel mirrors / V.G. Konovalov, M.N. Makhov, A.N. Shapoval, N. Ashikawa, S. Masuzaki, A. Sagara, D.I. Naidenkova, I.V. Ryzhkov, A.F. Shtan’, S.I. Solodovchenko, V.S. Voitsenya // Вопросы атомной науки и техники. — 2006. — № 6. — С. 244-246. — Бібліогр.: 3 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-07-06T08:51:36Z |
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2025-07-06T08:51:36Z |
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| fulltext |
Problems of Atomic Science and Technology. 2006, 6. Series: Plasma Physics (12), p. 244-246 244
-1 0 1
1
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3
4
5
IMAGE QUALITY AS A POSSIBLE METHOD OF IN SITU MONITORING
THE IN-VESSEL MIRRORS
V.G. Konovalov1, M.N. Makhov1, A.N. Shapoval1, N. Ashikawa2, S. Masuzaki2, A. Sagara2,
D.I. Naidenkova1, I.V. Ryzhkov1, A.F. Shtan’1, S.I. Solodovchenko1, V.S. Voitsenya1
1 Institute of Plasma Physics, NSC KIPT, Akademicheskaya Str. 1, 61108, Kharkov, Ukraine;
2 National Institute for Fusion Science, 322-6 Oroshi-cho Toki-shi 509-5292, Japan
The plasma facing mirrors (FM) in ITER will be subjected to sputtering and / or contamination with the rates
depending on mirror locations. The result of influence of both these factors will be reduce of mirror reflectance (R) and
worsen the quality of transmitted image (IQ). This implies that control of the mirror quality in- situ is an actual
problem, and this work is an attempt to approach to its solution. The method suggested for evaluation of IQ was applied
to mirrors exposed in LHD, TRIAM-1M, TS and in the DSM-2 stand (IPP NSC KIPT).
PACS: 52.40.Hf ; 78.68.+m; 79.20.Rf
INTRODUCTION
The degree of impact of sputtering and deposition will
depend on locations of elements of optical system in a
vacuum vessel. The sputtering of mirror results in
irreversible changes of its optical properties (OP).
However, if contaminated, e.g., with a carbon film, the
mirror can be recovered to the initial OP, using some
efficient method of cleaning.
The goal of this work: to investigate, to what degree
the specular component of reflected light survives in the
course of mirror degradation due to deposition of
contaminating film and long-term sputtering.
The structure of paper is as follows: in section 1) the
results of ex- situ measurements of OP (R, IQ) of mirrors
exposed in fusion devices LHD, TRIAM-1M, and Tore
Supra (TS) are presented; in section 2) the results of
laboratory experiments carried out in IPP NSC KIPT are
described. The stand for measurement of R over the range
of wavelengths 220…650 nm was assembled using the
optical scheme described in [1]. The optical scheme of IQ
stand is shown in Fig.1.
Fig. 1. The optical scheme for measuring IQ: (1) - light source, (2) - monochromator,
(3) – reference signal, (4)- test mirror, (5) - scanner of the enlarged image of the monochromator exit slit
1. OPTICAL RESEARCHES OF MIRRORS
EXPOSED IN LHD, TRIAM-1M, TS
1.1 LHD. In the 7-th (2003-2004) experimental campaign
three stainless steel mirrors (SS316) were exposed in
locations, shown in Fig.2.
Fig. 2. Lay-out of samples in vessel LHD
All samples were not protected from impact of glow-
discharge plasma during conditioning and boronization
procedures with total duration many times exceeded the
total duration of working discharges. The observed IQ
data are presented in Fig.3.
Fig. 3. IQ normalized for LHD-samples
The presented distributions characterize the quality of the
obtained information in the case that such mirror would
be used for a diagnostic aim. It is seen that IQ for sample
#3 does not completely coincide with that of an ideal (Al /
quartz) mirror. The wings of distributions correspond to
the diffusive component of R, and are connected with
structural changes of the mirror surface. The analysis of
the state of samples with the help of an optical
microscope has shown the presence of feebly marked
First wall
#3
#1 #5
Outer
Port
Inner
divertor
-1 0 1
0,0
0,5
1,0
Al
#1
#3
#5
X, mm
245
grain structure on the mirror #3 surface, without any trace
of deposition. Therefore, the appearance of wings has to
be attributed to the light scattering on the arisen surface
roughness. The samples #1 and #5 with the deposited film
of not known yet chemical composition, did not show any
apparent deviations from IQ for an ideal mirror.
1.2.TRIAM-1M. In the vessel of this tokamak five mirror
samples were installed: one monocrystalline Mo (mc-Mo)
and polycrystalline samples. After exposure, some
deposited film on all samples was detected resulting in
decrease of reflectance. The procedure of studying the
samples comprised in multi-step cleaning of their surface
in a deuterium ECR discharge plasma. After every single
exposure, the measurements of R and IQ were carried out.
In Fig.4 the IQ data are presented.
Fig. 4. Recovery of reflectivity (IQ method)
The normalized data of IQ for Mo and SS samples have
shown the complete accordance with an ideal mirror.
1.3. Tore Supra. The experiment at TS was provided with
two mirror samples of every of three metals: (mc-Mo),
pc- samples SS and oxygen free Cu. The mirror samples
were installed on the high field side of the vessel for long-
term exposure (2003-2004). The detail description of TS
experimental conditions is in [2, 3].
Total exposure a cumulated pulse length of working
discharges (D2) reached ~7.2 h. Wall conditioning was
provided by glow discharges in He (362 h) and D2 (606 h)
and also ~13 h of boronization.
1. Mc-Mo. Erosion depth (ED) ~ 0.12 µm. The decrease
of reflectance was connected with appearance of
contaminating film (C, B, O, H, D) of ~12 nm thick.
2. SS. ED ~ 0.22 µm. Slightly noticeable surface
roughness and corresponding diffusive component in
reflected light appeared.
3. Cu. ED ~2.5 µm and the topography was drastically
changed.
The observed data on IQ of the listed above mirrors are
given in Fig.5.
Fig. 5. IQ for TS samples
2. LABORATORY STUDY OF FILM-COATED
AND SPUTTER-ERODED MIRRORS
2.1 Film-coated mirror. One factor of reflectivity
degradation of the in-vessel mirrors is the deposition of
contaminating films, e.g., carbon. For clearing up their
role, we investigated the effects of such films deposited in
an arc discharge with graphite electrodes on the surface of
mc- (110) and SS samples. The thickness of films
varied from 30 to 50 nm. After cleaning the sample
surface by plasma of an ECR discharge in deuterium,
during several short (3-5 minutes) exposures without
supplying any potential, the sample was taken out and the
measurements of R (in the range =250…650 nm) and
IQ (at =550 nm) were carried out. The results of these
measurements are presented in Fig.6.
Fig, 6. Evolution of IQ by cleaning procedure
The normalization of this initial distributions, demonstrates
a quite good coincidence with a control Al mirror.
2.2 Sputter-eroded mirrors. For FMs of some diagnostics
in ITER will be important not only how they transmit the
amplitude of signal but also what quality is the image of
plasma or the surface of inner components transmitted by
given mirror system. Without high IQ, there is a problem
of adequate interpretation of optical measurements, e.g.,
the radial distributions of plasma radiation because the
effect of diffusive part of R should result in losses of an
image contrast. That is why, important is to investigate IQ
depending on the rate of sputter erosion of mirror and
deposition of contaminants. For experiments the pc Cu
and SS mirrors were chosen.
The single step sputtering mirrors was carried out in
series, using an ECR discharge in a simple double-mirror
magnetic trap (DSM-2). The time varying negative
potential was supplied to the sample holder what provided
a wide energy distribution of ions bombarded the mirror
surface in the range 30-1500 eV.
2.2.1. Copper samples. For clearing up of effect of grain
size of a surface mirror on optical properties copper
samples have been selected with small-grain (S-G)~
50…120 m and large-grain (L-G) ~ 500…1500 m.
Observed data for Cu S-G, as example, are shown on Fig.7.
Fig. 7. IQ at sputtering Cu S-G sample
-1 0 1
0,0
0,5
1,0
Al mirror
0 V, t=6min
60V, t=3min
60V, t=6min
60V, t=14min
X, mm
-1 0 1
0,0
0,5
1,0
X, mm
Al
Mo B
Mo A
SS A
SS B
Cu A
-1 0 1
0,0
0,5
1,0
Al mirror
t= 6 min
t=12 min
t=21 min
X, mm
-1 0 1
0,0
0,5
1,0
X, mm
Al
0,07 µm
0,13 µm
0,865 µm
1.43 µm
246
It is obvious, that the diffusive part of a reflected light
increases and the specular part decreases with increasing
the thickness of sputtered layer. A crude calculation of the
specular (SR) and diffusive (DR) parts of reflectivity is
possible by comparison of the areas under the distribution
curve in a central part and in wings.
The dynamics of ratio of SR and DR parts in depending
on the sputtered layer thickness is shown in Fig.8.
Fig. 8.The ratio of SR and DR components of a
reflectivity under sputtering Cu-SG and Cu-SG samples
Fig. 9. The ratio of a SR and DR components of
reflectivity under sputtering SS samples
2.2.2. Stainless steel samples (SS316). As it is known, for
conditioning of vacuum chamber a glow discharge with
different gases is used. Therefore, it is interesting to
compare the effects of different gases on IQ at equal
values of sputtered layer thickness. In our experiments the
comparison was made for hydrogen and argon working
gases. Results are given in Fig.9.
One can see a very surprising fact of not equal behaviour
of IQ on sputtered layer thickness for the same material of
a mirror for ions of H and Ar plasmas.
3. CONCLUSIONS
1. The optical properties of mirrors long-term exposed in
LHD, TRIAM-1M, Tore Supra and mirrors advisedly
coated with a carbon film or sputtered in a laboratory
stand were measured. It is shown, that the contaminating
film (≤ 50nm) practically does not influence the IQ
properties, but results in decrease of R only.
2. Under sputtering of polycrystalline materials,
accordingly, the IQ characteristics fall down. With that,
dynamics of ratio of specular and diffusive parts of the
total reflectivity was investigated.
3. The procedure of measurement of IQ principally
enables to distinguish between the reasons of
deterioration of mirror quality. In all cases investigated,
the deterioration of IQ occurred due to development of a
surface roughness but not due to contaminating film.
4. By modernization of suggested scheme of IQ
measuring, it would be possible to make an in-situ remote
monitoring of the quality of in-vessel mirrors in fusion
devices of the ITER scale.
REFERENCES
1. S.Tolansky. High Resolution Spectroscopy // IL,
Moscow. 1955, p.380 (in Russian).
2. M.Lipa, B.Schunke, Ch.Gil et al. // EFDA ref. TW2-
TPDS-DIADEV-D02, Final report, December 2004.
3. M.Lipa, et al. // Fusion Engineering and Design. 2006
v. 81, p. 221-225.
IN SITU ,
. , . , . , . , . , . , . ,
. , . , . , .
ITER / .
(R), (IQ).
, in- situ – .
. R IQ ,
LHD, TRIAM-1M, TS -2 (
).
IN SITU ,
. , . , . , . , . , . , . ,
. , . , . , .
ITER / .
(R), (IQ). ,
in- situ – . .
R IQ , LHD, TRIAM - 1M, TS
-2 ( ).
0 1 2 3 4
0
20
40
60
80
100
- diffusive reflectivity
- specular reflectivity
Sputtered layer, µm
Cu S-G
R
ef
le
ct
an
ce
, % Cu L-G
0 1 2 3
0
20
40
60
80
100
- specular reflectivity
- Ar - SS316
R
ef
le
ct
an
ce
, %
Sputtered layer, µm
- H - SS316
550 nm
- diffusive reflectivity
|