Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor
To introduce a visible radiation into plasma or to extract radiation from the vessel of a fusion device it is necessary to use the set of mirrors the first of which does directly see the hot plasma. It will undergo all types of plasma radiation– electromagnetic, nuclear and particle fluxes. The most...
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| Zitieren: | Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor / D. Orlinski, A.F. Bardamid, V. Konovalov, V. Kedrov, N. Klassen, A. Shtan’, A. Shapoval, S. Solodovchenko, G. Strukov, V. Voitsenya, K. Vukolov, K. Yakimov // Вопросы атомной науки и техники. — 2000. — № 3. — С. 67-69. — Бібліогр.: 7 назв. — англ. |
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irk-123456789-823862015-05-30T03:01:38Z Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor Orlinski, D. Bardamid, A.F. Konovalov, V. Kedrov, V. Klassen, N. Shtan, A. Shapoval, A. Solodovchenko, S. Strukov, G. Voitsenya, V. Vukolov, K. Yakimov, K. Мagnetic Confinement To introduce a visible radiation into plasma or to extract radiation from the vessel of a fusion device it is necessary to use the set of mirrors the first of which does directly see the hot plasma. It will undergo all types of plasma radiation– electromagnetic, nuclear and particle fluxes. The most dangerous for mirror surface will be the bombardment by particles. To have an optical system in a working state it is necessary to choose the first mirror (FM) material, which will assure to maintain the mirror optical properties for as long time as required. The aim of this work is testing rhodium as the FM material which, as known beforehand, is one of the stable materials under particle impact and has a quite high reflectance. Because of high cost, Rh cannot be used as a solid piece for FM fabrication, and it is necessary to deposit Rh layers (<10 mm) on substrates of appropriate metals. In the presented report the results of experiments on fabricating Rh mirrors and testing their properties are discussed. 2000 Article Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor / D. Orlinski, A.F. Bardamid, V. Konovalov, V. Kedrov, N. Klassen, A. Shtan’, A. Shapoval, S. Solodovchenko, G. Strukov, V. Voitsenya, K. Vukolov, K. Yakimov // Вопросы атомной науки и техники. — 2000. — № 3. — С. 67-69. — Бібліогр.: 7 назв. — англ. 1562-6016 http://dspace.nbuv.gov.ua/handle/123456789/82386 533.9 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Мagnetic Confinement Мagnetic Confinement |
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Мagnetic Confinement Мagnetic Confinement Orlinski, D. Bardamid, A.F. Konovalov, V. Kedrov, V. Klassen, N. Shtan, A. Shapoval, A. Solodovchenko, S. Strukov, G. Voitsenya, V. Vukolov, K. Yakimov, K. Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor Вопросы атомной науки и техники |
| description |
To introduce a visible radiation into plasma or to extract radiation from the vessel of a fusion device it is necessary to use the set of mirrors the first of which does directly see the hot plasma. It will undergo all types of plasma radiation– electromagnetic, nuclear and particle fluxes. The most dangerous for mirror surface will be the bombardment by particles. To have an optical system in a working state it is necessary to choose the first mirror (FM) material, which will assure to maintain the mirror optical properties for as long time as required. The aim of this work is testing rhodium as the FM material which, as known beforehand, is one of the stable materials under particle impact and has a quite high reflectance. Because of high cost, Rh cannot be used as a solid piece for FM fabrication, and it is necessary to deposit Rh layers (<10 mm) on substrates of appropriate metals. In the presented report the results of experiments on fabricating Rh mirrors and testing their properties are discussed. |
| format |
Article |
| author |
Orlinski, D. Bardamid, A.F. Konovalov, V. Kedrov, V. Klassen, N. Shtan, A. Shapoval, A. Solodovchenko, S. Strukov, G. Voitsenya, V. Vukolov, K. Yakimov, K. |
| author_facet |
Orlinski, D. Bardamid, A.F. Konovalov, V. Kedrov, V. Klassen, N. Shtan, A. Shapoval, A. Solodovchenko, S. Strukov, G. Voitsenya, V. Vukolov, K. Yakimov, K. |
| author_sort |
Orlinski, D. |
| title |
Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor |
| title_short |
Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor |
| title_full |
Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor |
| title_fullStr |
Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor |
| title_full_unstemmed |
Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor |
| title_sort |
rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2000 |
| topic_facet |
Мagnetic Confinement |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/82386 |
| citation_txt |
Rhodium as the promising material for the first mirrors of laser and spectroscopy methods of plasma diagnostics in a fusion reactor / D. Orlinski, A.F. Bardamid, V. Konovalov, V. Kedrov, N. Klassen, A. Shtan’, A. Shapoval, S. Solodovchenko, G. Strukov, V. Voitsenya, K. Vukolov, K. Yakimov // Вопросы атомной науки и техники. — 2000. — № 3. — С. 67-69. — Бібліогр.: 7 назв. — англ. |
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Вопросы атомной науки и техники |
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| fulltext |
UDC 533.9
Problems of Atomic Science and Technology. 2000. N 3. Series: Plasma Physics (5). p. 67-69 67
RHODIUM AS THE PROMISING MATERIAL FOR THE FIRST
MIRRORS OF LASER AND SPECTROSCOPY METHODS OF PLASMA
DIAGNOSTICS IN A FUSION REACTOR
D.Orlinski1,A.F.Bardamid2, V.Konovalov, V.Kedrov3, N.Klassen4, ,A.Shtan’, A.Shapoval,
S.Solodovchenko, G.Strukov3, ,V.Voitsenya, K.Vukolov1, K.Yakimov2
NSC Kharkov Institute of Physics and Technology, 61108 Kharkov, Ukraine;
1RRC, Kurchatov Institute, Moscow, Russia; 2Kiev University, 01033 Kiev, Ukraine;
3IPSP, Chernogolovka, Moscow Region, Russia; 4ISSP, Chernogolovka, Moscow Region, Russia
To introduce a visible radiation into plasma or to extract radiation from the vessel of a fusion device it is
necessary to use the set of mirrors the first of which does directly see the hot plasma. It will undergo all types of
plasma radiation– electromagnetic, nuclear and particle fluxes. The most dangerous for mirror surface will be the
bombardment by particles. To have an optical system in a working state it is necessary to choose the first mirror
(FM) material, which will assure to maintain the mirror optical properties for as long time as required. The aim of
this work is testing rhodium as the FM material which, as known beforehand, is one of the stable materials under
particle impact and has a quite high reflectance. Because of high cost, Rh cannot be used as a solid piece for FM
fabrication, and it is necessary to deposit Rh layers (<10 µm) on substrates of appropriate metals. In the presented
report the results of experiments on fabricating Rh mirrors and testing their properties are discussed.
1. Introduction
The mirrors made of Ag, Al, Cu and Rh have
better spectral characteristics of reflectance in
visible region than many other metals (Fig.1). In
usual atmospheric and vacuum conditions Al and
Ag are used for metal mirrors. However, the
environment conditions for mirrors in a fusion
reactor are much more difficult. The surface of the
first mirror (FM) - i.e. that nearest to the plasma,
will undergo to influence of some kinds radiation
of a hot plasma: electromagnetic, nuclear, (gammas
and neutrons) and charge exchange atoms (CXA)
with energy depending on the ion temperature at the
plasma periphery. As was shown in previous
investigation [1], the nuclear radiation leads to the
mirror body heating resulting in some deformation
of mirror but almost without surface degradation. In
the case of Thomson scattering based on a multi-
shot laser operation, the conditions can be realized
(pulse power and frequency) at which mirror
surface will deteriorate, but in other conditions, the
repeated laser pulses can be used for cleaning the
mirror surface from different kinds of deposit.
The most dangerous for the mirror surfaces are CXA
fluxes that cause the surface sputtering and increase the
scattering of incident light. Fig.2 shows the behavior of
reflectance of mirrors fabricated of polycrystalline
metals depending on the sputtered layer thickness. The
data for thick Rh film (~10µm) obtained later than
others, were added to results obtained earlier [2] (1µm
correspond to ~5000 monolayers). As seen from Fig.2,
among all metals shown the Rh mirror was the most
resistant one.
The figure of merit, i.e., the ratio of the reflectivity to
sputtering yield is also much better for Rh than for
many metals [1]. Other proper metals (stainless steel
and Mo) have lower reflectance.
A rather high and uniform reflectance [3],
important for diagnostics with laser radiation in use,
and low sputtering yield under CXA bombardment
allow to consider rhodium as candidate material for
mirrors located in the most hard conditions inside the
fusion reactor. At the same time, a very high cost of
this metal forces to look for methods which give
20
30
40
50
60
70
80
90
0 1 2 3 4 5
600nm
R
ef
le
ct
an
ce
,
%
Thickness of sputtered layer, µµ m
Rh (ISSP)
Cu
Mo
W
Al Ta
SS
Rh (Coherent
Comp.)
Fig.2. Reflectance of different metals dependence
on the sputtered layer thickness.
0
20
40
60
80
100
200 400 600 800 1000
R
ef
le
ct
an
ce
, %
Wavelength, nm
Al
Ag
Rh
Cu
W
Mo
Fig.1 Spectral reflectance at normal incidence for
several prospect metals.
68
possibility to use not bulk, but thin reflecting
rhodium films of reasonable thickness and quality.
2. Rhodium film-mirrors
Beside of high reflectivity in visible, rather
small sputtering yield, relatively big thickness (up
to 10 µm) and small grain size homogeneity there
are two more important requirements for reflecting
rhodium films: its reflectance must not change
during long-term sputtering and adhesion of film to
the substrate must be high. There are several ways
of film deposition – electrodeposition [4],
deposition of magnetron sputtered rhodium at an
enhanced voltage [5] and electrolytic deposition
with subsequent pressing of deposited film [6].
Unfortunately in Dr. Orsitto`s final report [4]
there are no data on technology of Rh deposition
and on results of test. In [5] the method of Rh film
deposition on vanadium and stainless steel
substrates in a magnetron discharge was developed
and was found the good reflectance and rather small
diffusive scattering. Adhesion was not measured
and sputtering effect on reflectance was not studied.
By the last method [6], developed in the Institute
of Solid State Physics (ISSP), the rhodium mirrors
were fabricated by combination of chemical and
electroplating deposition of Rh films on the copper
and copper-nickel substrates followed by pressing
and annealing treatments of rhodium coating.
The combination of chemical-electroplating
deposition of Rh with pressing-annealing treatment
of coatings gave a quite high adhesion (not less 5-
10 MPa) as was confirmed by direct measurements
at ISSP and indirectly by irradiation tests in
Kharkov. Electron microscopy studies showed that
such good adhesion is result of mutual penetration
of Rh coating and substrate materials during the
deposition and subsequent pressing and annealing.
The preservation of a high specular reflection of
the coating during the removal of several microns
of Rh film by an intensive ion irradiation turned out
to be more problematic task. Traditional abrasive
polishing of coatings produced a satisfactory initial
level of specular optical reflection (up to 80 %),
close to the ideal reflection from a Rh surface. But
soon after beginning irradiation, when the first
micrometers of the coating have been removed by
ion sputtering, the specular reflectance decreased.
This fall down of reflectance is explained by the
irradiation etching of the structural defects,
produced in the subsurface layer by the abrasive
treatment, which induce the light scattering.
In order to achieve necessary optical parameters
of Rh film mirrors, two main problems should be
solved. The internal structure of Rh films should be
nanocrystalline with homogeneously distributed
grains having dimensions not bigger than 50 nm
and the surface of film should be optically smooth
and flat without abrasive treatment, disturbing the
subsurface structure.
Experimental tests of Rh film mirrors subjected to
ion sputtering, showed that some mirrors are close to
these requirements: the initial specular reflectance at
wavelengths 600-650 nm (Fig.3) was about 75-80 %
and its decrease during sputtering removal of 2 - 3 µm
did not exceed 5 %.
The procedure of test included the step by step
exposures to flux of ions of deuterium plasma with a
wide energy spectrum (0.1-1.5 keV) [7] and
measurements of mass loss and reflectance of the
sample after every step. The best data for two Rh film
mirrors fabricated as Rh films on Cu substrate are
shown in Fig.4 (in relative units) for the wavelength
600 nm. For comparison similar data for
polycrystalline copper and stainless steel mirrors are
added. The adhesion of Rh film was good and on the
interface surface there was not found bubbles which
were observed in identical tests for some other film-
substrate pairs.
3. Discussion
It follows from results of the test that some Rh film
mirrors maintained a high reflectance even after
sputtering the surface layer of ~7µm thick. This result
is the best among all polycrystalline mirror materials
50
55
60
65
70
75
80
85
0 0.5 1 1.5 2 2.5
Rh on Cu
R
ef
le
ct
an
ce
, %
650nm
#3
#4
#3
#4
400nm Res. pow.
R
es
ol
ut
io
n
po
w
er
, l
in
e/
m
m
Thickness of sputtered layer, µµm
Fig.3. Dependence of reflectance and resolving
power of Rh film on Cu substrate on the sputtered layer
thickness.
0.8
0.9
1
0 1 2 3 4 5 6 7 8
600nm
R
el
at
iv
e
re
fl
ec
ta
nc
e
Cu
SS
Rh
Thickness of sputtered layer, µµm
Fig.4. Dependence of relative reflectance for Rh film
on Cu substrate, polycrystalline Cu and stainless steel
mirrors on the sputtered layer thickness.
69
tested: Be, Al, SS, Cu, Mo, W, Ta, and film Be/Cu,
Cu/Cu. Thus, rhodium film mirrors on a metal
substrate look very promising for fabrication of the
first mirrors, which will be able to maintain the
initial reflectance during long time operation being
subjected to expected CXA fluxes.
Investigations of the rhodium film by means of
scanning and transmission electron microscopes
have shown (Fig.5) that films have a fine-grained
structure with the grain size of ~50 nm. The finesse
of films is assured by a plastic deformation in the
near surface layer of samples and thus the isotropy
of film surface properties is realized. Therefore
defects that are usually characteristic for materials
with the relatively large sizes of volumetric
polycrystals [7] do not appear when Rh films are
subjected to a long–term ion bombardment. Thus,
the microrelief of the film surface with small
roughness (of the order of the grain size ~50 nm)
being maintained during long-term ion
bombardment, does not result in significant
degradation of mirror reflectance. During the entire
test, such mirrors retain a good image transmission
properties, i.e. the high resolving power.
4. Conclusion
From comparative analysis of presented data and
data on behavior of different mirror materials under
analogous tests, one can make a realistic conclusion
that rhodium is a prospect material for fabrication of
mirrors which have to be installed inside the fusion
reactor vacuum vessel and to be the plasma facing
components.
In order to improve the initial optical quality of the
surface without any abrasive usage it is supposed to
apply combined chemical-mechanical and deformation
treatments. When the main parameters of the process as
a whole will be found (i.e. temperature and
concentration of the solutions, duration of the
deposition process, current density, mechanical
pressure, etc.), it will be possible to proceed to
development of the process for the manufacturing of
large size rhodium film mirrors.
Fig.5. The structure of Rh film: a - SEM image of a rod-like structure in the fracture of film near the through crack,
b - TEM photo of a surface replica
References
[1]. V.S.Voitsenya, A.F.Bardamid, V.I.Bereghnyj et al. In Diagnostics for Experimental Thermonuclear Fusion
Reactors, Ed. by P.E.Stott, G.Gorini and E.Sindoni, Plenum Press, N.Y., 1996
[2]. A.F.Bardamid, V.G.Konovalov, D.V.Orlinski et al. Problems of Atomic Science and Technology, Series Plasma
Phys., isue.1-2, Kharkov 1999, p.124.
[3]. Y.Yamamura and H.Tawara. NIFS-DATA-23, Nagoya, 1995.
[4]. F.Orsitto, D.Del Bugaro, M.Di Fino et al. Optical characterization of plasma facing mirrors for a Thomson
scattering system of a burning plasma experiment. Paper BP19 at 13th HTPD, Tucson, USA, June 2000.
[5]. K.Vukolov, A.Volkov, V.Sannikov and A.Gorshkov, “Development of technology for manufactory of core
region first mirrors and study of their properties” Final Report of ITER Task No.347, 1997-1998.
[6]. N.V.Klassen, S.I.Makhonin and Yu.A.Osipyan, “On application of plastic deformation when manufacturing the
optical elements”, “Materialovedenie” 1997, No.2, p.47 (in Russian).
[7]. A.F.Bardamid, V.T.Gritsyna, V.G.Konovalov et al. Surface Coating & Technology, 103-104 (1998) 365.
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