Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER
In optical methods of plasma diagnostics in large fusion devices (FD) the use of first mirrors (FM) is supposed. To make the right choice of FM material the modeling studies are needed of the degradation rates of reflectance and image transmission quality (ITQ) under sputtering in FDs. In the presen...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2005
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| Назва видання: | Вопросы атомной науки и техники |
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| Цитувати: | Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER / V.G. Konovalov, A.N.Shapoval, O.Yu. Volkova, V.S. Voitsenya // Вопросы атомной науки и техники. — 2005. — № 2. — С. 46-48. — англ. |
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irk-123456789-793422015-04-01T03:02:14Z Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER Konovalov, V.G. Shapoval, A.N. Volkova, O.Yu. Voitsenya, V.S. ITER and fusion reactor aspects In optical methods of plasma diagnostics in large fusion devices (FD) the use of first mirrors (FM) is supposed. To make the right choice of FM material the modeling studies are needed of the degradation rates of reflectance and image transmission quality (ITQ) under sputtering in FDs. In the present paper the method is suggested and applied for evaluation of ITQ. The use of scheme with photoelectrical registration of the luminous object image allows measuring the dynamics of the change of the contrast and resolving power of mirror depending on the depth of layer eroded due to bombardment with deuterium ions. As an example, the comparative results are presented on degradation of optical properties of two Cu mirror samples with coarse-and small-grain structures. В оптичних методах діагностики на великих термоядерних установках (ТЯУ) передбачається використовувати перші дзеркала (ПДЗ). При виборі матеріалу для ПДЗ необхідні модельні дослідження деградації як коефіцієнту відображення так і якості зображення (ЯПЗ) при розпиленні в умовах ТЯУ. В даній роботі запропонована і застосована методика оцінки ЯПЗ з використанням фотоелектричної реєстрації зображення об'єкту, яка дозволяє вимірити динаміку зміни контрасту і роздільної здатності по мірі збільшення товщини розпиленого шару при бомбардуванні зразків потоками іонів дейтерієвої плазми. Як приклад наводяться результати дослідження деградації оптичних характеристик двох мідних зразків з крупною та дрібнозернистою структурами. В оптических методах диагностики на крупных термоядерных установках (ТЯУ) предполагается использовать первые зеркала (ПЗ). При выборе материала для ПЗ необходимы модельные исследования деградации, как коэффициента отражения, так и качества изображения (КПИ) при распылении в условиях ТЯУ. В данной работе предложена и применена методика оценки КПИ с использованием фотоэлектрической регистрации изображения объекта, позволяющая измерить динамику изменения контраста и разрешающей способности по мере увеличения толщины распылённого слоя при бомбардировке образцов потоками ионов дейтериевой плазмы. В качестве примера приводятся результаты исследования деградации оптических характеристик двух медных образцов с крупной и мелкозернистой структурами. 2005 Article Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER / V.G. Konovalov, A.N.Shapoval, O.Yu. Volkova, V.S. Voitsenya // Вопросы атомной науки и техники. — 2005. — № 2. — С. 46-48. — англ. 1562-6016 PACS: 28.52.-s; 42.82.Bq; 42.88.+h http://dspace.nbuv.gov.ua/handle/123456789/79342 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| language |
English |
| topic |
ITER and fusion reactor aspects ITER and fusion reactor aspects |
| spellingShingle |
ITER and fusion reactor aspects ITER and fusion reactor aspects Konovalov, V.G. Shapoval, A.N. Volkova, O.Yu. Voitsenya, V.S. Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER Вопросы атомной науки и техники |
| description |
In optical methods of plasma diagnostics in large fusion devices (FD) the use of first mirrors (FM) is supposed. To make the right choice of FM material the modeling studies are needed of the degradation rates of reflectance and image transmission quality (ITQ) under sputtering in FDs. In the present paper the method is suggested and applied for evaluation of ITQ. The use of scheme with photoelectrical registration of the luminous object image allows measuring the dynamics of the change of the contrast and resolving power of mirror depending on the depth of layer eroded due to bombardment with deuterium ions. As an example, the comparative results are presented on degradation of optical properties of two Cu mirror samples with coarse-and small-grain structures. |
| format |
Article |
| author |
Konovalov, V.G. Shapoval, A.N. Volkova, O.Yu. Voitsenya, V.S. |
| author_facet |
Konovalov, V.G. Shapoval, A.N. Volkova, O.Yu. Voitsenya, V.S. |
| author_sort |
Konovalov, V.G. |
| title |
Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER |
| title_short |
Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER |
| title_full |
Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER |
| title_fullStr |
Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER |
| title_full_unstemmed |
Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER |
| title_sort |
experimental modelling of the effects of cxa bombardment on image quality of the first mirrors in iter |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2005 |
| topic_facet |
ITER and fusion reactor aspects |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/79342 |
| citation_txt |
Experimental modelling of the effects of CXA bombardment on image quality of the first mirrors in ITER / V.G. Konovalov, A.N.Shapoval, O.Yu. Volkova, V.S. Voitsenya // Вопросы атомной науки и техники. — 2005. — № 2. — С. 46-48. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-07-06T03:25:13Z |
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| fulltext |
EXPERIMENTAL MODELLING OF THE EFFECTS
OF CXA BOMBARDMENT
ON IMAGE QUALITY OF THE FIRST MIRRORS IN ITER
V.G. Konovalov, A.N. Shapoval, O.Yu. Volkova, V.S. Voitsenya
Institute of Plasma Physics, NSC KIPT, 61108, Kharkov, Ukraine
In optical methods of plasma diagnostics in large fusion devices (FD) the use of first mirrors (FM) is supposed.
To make the right choice of FM material the modeling studies are needed of the degradation rates of reflectance and
image transmission quality (ITQ) under sputtering in FDs. In the present paper the method is suggested and applied for
evaluation of ITQ. The use of scheme with photoelectrical registration of the luminous object image allows measuring
the dynamics of the change of the contrast and resolving power of mirror depending on the depth of layer eroded due to
bombardment with deuterium ions. As an example, the comparative results are presented on degradation of optical
properties of two Cu mirror samples with coarse-and small-grain structures.
PACS: 28.52.-s; 42.82.Bq; 42.88.+h
INTRODUCTION
Optical methods of plasma diagnostics are
routinely used at fusion devices. In the reactor-grade
fusion devices (e.g., ITER) the optical systems have to
include such in-vessel components as the first mirrors
(FM). The main demand to FM is the high resistance to
damaging factors in a harsh ITER environment. Such
factors are: gammas, neutrons, x-rays, and charge
exchange atoms (CXA). As was shown previously in
NSC KIPT, for metallic FMs the most critical factor is
bombardment by CXA leading to development of the
roughen surface, i.e., to degradation of reflectance and
deterioration of the mirror ability to transmit an image.
At the present day the FM program in NSC KIPT
is based on modeling experiments with investigation of
effects of long-term bombardment by deuterium plasma
ions on optical properties of mirrors from different
materials with different structure.
To control the quality of the image transmission
by tested mirror, the resolving power was measured
earlier by means of the collimating system OSK-2. Such
measurements are not vivid and have a rather subjective
character. Recently, the special optical stand was
designed and built up with the scanning arrangement and
a photomultiplier giving a possibility to measure the
profiles of the strongly enlarged image of the
incandescent lamp filament by means of the scheme that
includes the mirror under the test. To demonstrate the
prospects of such an approach, the first comparative
results were obtained on the dynamics under ion
bombardment of an image transmission quality (in terms
of resolving power and contrast) for two copper mirrors:
with fine- and coarse-grained structures.
TEST STAND
Fig. 1 shows the main components of the stand: 1)
incandescent lamp SI6-40 (the width of the W ribbon is
0.66 mm), 2) diaphragm with a round aperture, 3) the
mirror under consideration, 4) objective, 5) standard
spectral slit, 7) photomultiplier.
The luminous flux from the lamp falls at angle of
45° on the mirror sample through the diaphragm aperture
intended for suppression of a parasitic background; after
reflection from the sample the light passes through an
objective which focuses the enlarged image (m≥7) of the
incandescent lamp ribbon in the form of a rectangle in the
plane of a scanning slit.
1
2
3
4 5
6
Fig. 1. The block representation for investigation of the
image quality of the tested mirrors
A spatial scan in the plane of the light source image
was provided by simultaneous moving of the slit -
photomultiplier block fixed at a special table with a reading
scale. Before providing measurement with the mirror
samples, the initial characteristics of the whole optical
scheme itself were studied. For that an “ideal” mirror (Al
film on a high optical quality quartz substrate) was installed
instead of the test mirror, and the image of the light source
was measured. As seen (Fig. 2), the image is not strictly
rectangular. The smeared edges (i.e., the side transition
regions along the X axis) are due to imperfection of the
resolving power of the objective and mirror and due to
diffraction on the slit in front of the photomultiplier. The
image shown in Fig. 2 can be taken as an instrumental
function of the optical scheme of the stand.
-10 -5 0 5 10
0,0
0,5
1,0
B
rig
ht
ne
ss
(a
rb
.u
ni
ts
)
Dimensions of the luminous object,mm
Fig. 2. Distribution of brightness of an enlarged image of
the incandescent lamp ribbon at a transverse scanning
with an ideal mirror (Al) in use
46 Problems of Atomic Science and Technology. Series: Plasma Physics (11). 2005. № 2. P. 46-48
The quantitative estimations of resolving power were
provided in accordance with the Raleigh criterion.
0 2 4 6 8 10
0,0
0,2
0,4
0,6
0,8
1,0
B
rig
ht
ne
ss
(
ar
b.
un
its
)
Dimensions of the luminous object, mm
B
m
in
B
m
ax
Fig. 3. The scheme of determination of the contrast and
the limiting linear (and angle) resolution
RESULTS
The specificity of measurement of resolving power
is in the next. After measurement of distributions of the
incandescent lamp ribbon image, we conceive these
distributions as two independent light sources. By
changing the distance between them we shall create the
situation when the depth of depression in the total
intensity of overlapping contours starts to correspond to
requirement of the Raleigh criterion.
An idealized picture is shown in Fig.3. In this
figure is also presented the definition of the contrast for
our condition as:
K=
Bmax−Bmin
Bmin
,
where B is brightness of the image, and Bmax and Bmin are
shown on the graph.
To gain insight about possibilities of the given
approach for evaluation of the image transmission quality
we compared the dynamics of image transmission for two
Cu mirrors with different structures (small grains and
large grains) that were subjected to long-term ion
sputtering. The results of measurements with
abovementioned method are shown in Figs. 4 and 5.
-5 0 5
0,0
0,5
1,0
t1=25'
t2=65'
t3=95'
B
ri
gh
tn
es
s,
(
ar
b
.u
n
it
s)
Dimensions of the luminous object, mm
Cu #1
Fig. 4. The set of curves for dependences of light intensity
transmitted by the small-grain Cu mirror on the linear
size of the light object at successive exposures to ion
bombardment. Total times of exposure are in the insert
As seen from graphs of Figs. 4 and 5, the intensity of the
central part of image decreases with every next sputtering
exposure and at the same time the intensity in wings rises.
Such a dynamics of a ribbon image is explained by rising
the portion of scattered light because of appearance and
development of the roughness on the mirror surface with
increasing the total time of ion sputtering. Note that the
lateral sides of transmitted images are continuing to be
straight lines for both Cu samples, what indicate on partial
maintenance of a specular component of the image
transmitted by samples. From comparing data for both
mirror samples one may conclude that the rate of
degradation of transmitted image quality is significantly
faster for the small-grain sample (Cu #1) than for the
large-grain sample (Cu #2).
-5 0 5
0,0
0,5
1,0
t1=25'
t2=65'
t3=95'
B
ri
gh
tn
es
s,
(
ar
b.
un
it
s)
Dimensions of the luminous object, mm
Cu #2
Fig. 5. The set of curves for dependences of light intensity
transmitted by the large-grain Cu mirror on the linear
size of the light object at successive exposures to ion
bombardment
0,0 0,5 1,0
0,01
0,1
1
10
t1=25'
t2=65'
t3=95'
Cu #1
C
on
tr
as
t
Distance between luminous objects, mm
Fig. 6. The image contrast of two objects upon the
distance between their opposite points after successive
exposures for mirror Cu #1
0,0 0,5 1,0
0,01
0,1
1
10
t1=25'
t2=65'
t3=95'
Cu #2
C
on
tr
as
t
Distance between luminous objects, mm
Fig.7. The image contrast of two objects upon the
distance between their opposite points after successive
exposures for mirror Cu #2
47
With an aim to obtain a pictorial view on dynamics of
resolving power and contrast the data shown in Figs. 4
and 5 were handled by means of the procedure described
above, and the final results are presented in Figs. 6-8. In
Figs. 6,7 the change of the contrast of image for two
objects is shown as functions of increasing distance
between their opposite points at successive exposures.
In Fig. 8 for both mirrors the dynamics of
degradation of resolving power is shown as function of
the depth of layer eroded due to ion sputtering. The
resolving power was found as a reciprocal value of the
limiting angle [α(sec)] resolution between two luminous
objects.
0,5 1,0 1,5 2,0 2,5
0,025
0,050
R
es
ol
vi
ng
p
ow
er
, 1
/ α
(s
ec
)
Cu #1
Cu #2
Thickness of sputtered layer, mm
Fig. 8. Degradation of the resolving power of mirror
samples Cu #1 and Cu #2 for K=0.25 with increasing the
depth of layer eroded by ion sputtering
It is necessary to note that the difference in structure of
the mirror samples was found out after preliminary
exposure. Therefore, on our regret, the presented results
do not relate to the degradation of optical properties
beginning from the initial state.
CONCLUSION
It was found that after similar ion fluence the fine-
grained copper mirror degraded faster and became to
have much higher portion of a diffusive component of
reflected light than the coarse-grained mirror.
On our point, the described method allows:
1. To obtain a vivid picture on degradation of the quality
of an image transmitted by the first mirror which is
being gradually sputtered by charge exchange atoms
flux in the ITER environment.
2. To obtain for the given optical channel the
quantitative data on the time dependence of degradation
of resolving power in the angle (seconds-1) or linear
(cross strokes per mm) units.
3. In combination with data on reflectance, to have more
complete information on the rate of degradation of the in-
vessel mirror being exposed in large fusion devices.
ЭКСПЕРИМЕНТАЛЬНОЕ МОДЕЛИРОВАНИЕ ВЛИЯНИЯ БОМБАРДИРОВКИ ПЕРВЫХ ЗЕРКАЛ
ПОТОКАМИ ПЕРЕЗАРЯЖЕННЫХ АТОМОВ
НА КАЧЕСТВО ПЕРЕДАВАЕМОГО ИЗОБРАЖЕНИЯ В ITER’e
В.Г. Коновалов, А.Н. Шаповал, О.Ю. Волкова, В.С. Войценя
В оптических методах диагностики на крупных термоядерных установках (ТЯУ) предполагается использовать
первые зеркала (ПЗ). При выборе материала для ПЗ необходимы модельные исследования деградации, как
коэффициента отражения, так и качества изображения (КПИ) при распылении в условиях ТЯУ. В данной
работе предложена и применена методика оценки КПИ с использованием фотоэлектрической регистрации
изображения объекта, позволяющая измерить динамику изменения контраста и разрешающей способности по
мере увеличения толщины распылённого слоя при бомбардировке образцов потоками ионов дейтериевой
плазмы. В качестве примера приводятся результаты исследования деградации оптических характеристик двух
медных образцов с крупной и мелкозернистой структурами.
ЕКСПЕРИМЕНТАЛЬНЕ МОДЕЛЮВАННЯ ВПЛИВУ БОМБАРДИРОВКИ ПЕРШИХ ДЗЕРКАЛ
ПОТОКАМИ ПЕРЕЗАРЯДЖЕНИХ АТОМІВ НА ЯКІСТЬ ПЕРЕДАВАЄМОГО ЗОБРАЖЕННЯ В ITER’і
В.Г. Коновалов, А.Н. Шаповал, О.Ю. Волкова, В.С. Войценя
В оптичних методах діагностики на великих термоядерних установках (ТЯУ) передбачається
використовувати перші дзеркала (ПДЗ). При виборі матеріалу для ПДЗ необхідні модельні дослідження
деградації як коефіцієнту відображення так і якості зображення (ЯПЗ) при розпиленні в умовах ТЯУ. В даній
роботі запропонована і застосована методика оцінки ЯПЗ з використанням фотоелектричної реєстрації
зображення об'єкту, яка дозволяє вимірити динаміку зміни контрасту і роздільної здатності по мірі збільшення
товщини розпиленого шару при бомбардуванні зразків потоками іонів дейтерієвої плазми. Як приклад
наводяться результати дослідження деградації оптичних характеристик двох мідних зразків з крупною та
дрібнозернистою структурами.
48
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