Tungsten coatings under fusion relevant heat loads
Components for first wall applications in future nuclear fusion devices like ITER or DEMO need to fulfill special requirements. Especially transient thermal loads like Edge Localized Modes (ELMs) have a severe impact on the material damage. Tungsten coatings are being assessed for use instead of bul...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2010
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Tungsten coatings under fusion relevant heat loads / C. Thomser, J. Linke, G. Matthews, V. Riccardo, A. Schmidt, V. Vasechko // Вопросы атомной науки и техники. — 2010. — № 6. — С. 54-56. — Бібліогр.: 1 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860262335228149760 |
|---|---|
| author | Thomser, C. Linke, J. Matthews, G. Riccardo, V. Schmidt, A. Vasechko, V. |
| author_facet | Thomser, C. Linke, J. Matthews, G. Riccardo, V. Schmidt, A. Vasechko, V. |
| citation_txt | Tungsten coatings under fusion relevant heat loads / C. Thomser, J. Linke, G. Matthews, V. Riccardo, A. Schmidt, V. Vasechko // Вопросы атомной науки и техники. — 2010. — № 6. — С. 54-56. — Бібліогр.: 1 назв. — англ. |
| collection | DSpace DC |
| description | Components for first wall applications in future nuclear fusion devices like ITER or DEMO need to fulfill special requirements. Especially transient thermal loads like Edge Localized Modes (ELMs) have a severe impact on the material damage. Tungsten coatings are being assessed for use instead of bulk tungsten. In order to quantify their material degradation, tungsten coatings on a fiber-reinforced graphite substrate were exposed to repeated short fusion relevant thermal pulses in an electron beam material test facility JUDITH 1 (Juelich Divertor Test Facility in Hot Cells).
|
| first_indexed | 2025-12-07T18:56:55Z |
| format | Article |
| fulltext |
54 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2010. 6.
Series: Plasma Physics (16), p. 54-56.
TUNGSTEN COATINGS UNDER FUSION RELEVANT HEAT LOADS
C. Thomser1, J. Linke1, G. Matthews2, V. Riccardo2, A. Schmidt1, V. Vasechko1
1Forschungszentrum Jülich EURATOM-Association FZJ, D-52425 Jülich, Germany;
2Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, UK
E-mail: c.thomser@fz-juelich.de
Components for first wall applications in future nuclear fusion devices like ITER or DEMO need to fulfill special
requirements. Especially transient thermal loads like Edge Localized Modes (ELMs) have a severe impact on the
material damage. Tungsten coatings are being assessed for use instead of bulk tungsten. In order to quantify their
material degradation, tungsten coatings on a fiber-reinforced graphite substrate were exposed to repeated short fusion
relevant thermal pulses in an electron beam material test facility JUDITH 1 (Juelich Divertor Test Facility in Hot Cells).
PACS: 28.52.Fa
1. INTRODUCTION
First wall components for applications in future
nuclear fusion devices need to fulfil special requirements,
e.g. a good thermal conductivity, a reasonable strength
value as well as a good compatibility with a deuterium /
tritium plasma. Moreover neutron irradiation has not to
lead to an unacceptable activation and a significant
degradation of material properties. Especially transient
and / or cyclic thermal loads in magnetic confinement
experiments like ITER have a severe impact on the
material damage of the plasma facing components.
Tungsten coatings are being assessed for use instead
of bulk tungsten components. Within the ITER like wall
project, realised at JET, a part of the thermally loaded
wall will consist of tungsten coated CFC modules.
In order to quantify the material degradation under
transient ELM – like heat loads (Edge Localised Modes),
tungsten coatings on a fibre-reinforced graphite substrate
were exposed to short fusion relevant thermal pulses in
the electron beam material test facility JUDITH 1 (Juelich
Divertor Test Facility in Hot Cells). In addition the failure
mechanism of the coatings was investigated.
2. THERMAL SHOCK TESTS
The applied test parameters for the thermal shock tests
in the electron beam facility JUDITH 1 are as follows:
- Sample size: 12 x 12 x 5 mm
- Absorbed power densities: 79…316 MW/m2
- Electron absorption coefficient: 0.46
- Base temperature: 22…400 °C
- Loaded area: 4 x 4 mm
- Pulse duration: 1 ms
- Inter pulse time: 2 s
- Beam scanning frequency (x / y): 31 kHz / 40 kHz
- Number of pulses: 100
- Electron beam diameter: 1 mm
A picture of the electron beam facility JUDITH 1 is
presented in Fig. 1.
Fig. 1. Electron beam material test device JUDITH 1
3. MATERIAL
A cross – section of the tested coating is presented in
Fig. 2. The coating has a total thickness of 20…25 µm
and consists of a double layer structure of tungsten and
molybdenum. The coating was produced by a Combined
Magnetron Sputtering and Ion Implantation (CMSII)
coating technique in Romania [1].
Fig. 2. Cross section of the tungsten coating
4. RESULTS
The delamination of the coating starts at absorbed
power densities of about 158 MW/m2 for nearly the whole
range of investigated temperatures. With increasing
power density material degradation is increasing.
Delamination always begins on the parallel fibers of the
CFC substrate, like it is shown in the SEM picture in
Fig.3.
25 µm
tungstenmolybdenum
CFC substrate Dunlop DMS 780
mailto:c.thomser@fz-juelich.de
55
Fig. 3. SEM picture of the delamination of the coating,
158 MW/m2, 1 ms, 100 shots, room temperature
In Fig. 4 and Fig.5 additionally crack formation and
melting for different loading conditions are presented.
Fig. 4. SEM picture of the failure of the coating,
158 MW/m2, 1 ms, 100 shots, base temperature 100 °C
Fig. 5. SEM picture of the failure of the coating,
237 MW/m2, 1 ms, 100 shots, base temperature 100 °C
An overview about the failure occurrence in
dependence on the absorbed power density and base
temperature is given in Fig. 6.
0
100
200
300
400
500
0 100 200 300 400 500
Base temperature, °C
A
bs
or
be
d
po
w
er
d
en
si
ty
, M
W
/m
2
No damage
Surface modification
Cracking
Delamination and cracking
Delamination, cracking and melting
Fig. 6. Overview about the damage mechanisms
of the tungsten coating
Only a small influence of base temperature can be
observed especially for the highest absorbed power
density. With increasing temperature the delaminated area
is decreasing (two samples are shown as an example in
Fig. 7). However, the temperature influence seems not to
play the major role for the degradation of the coating.
delaminated area
Fig. 7. Influence of temperature on the delamination
of the coating, 316 MW/m2, 1 ms, 100 shots
Moreover, spark erosion is documented by an optical
camera in the first shot of the experiments. The exposure
time was 5 s, i.e. the trajectories of all ejected particles are
recorded in the photographs. Almost no erosion can be
found at power densities below 158 MW/m2. For higher
power densities heavy spark erosion is observed, which a
hint for the delamination of the coating is. The magnitude of
spark erosion is dependent on the absorbed power density,
like it is presented for two examples in Fig. 8 and 9.
Fig. 8. Spark erosion, absorbed power density
237 MW/m2, 1 ms, 100 shots, room temperature
12 mm
400 °C 100 °C
delaminated parallel CFC fiber
tungsten coating
delamination
cracking
delamination
cracking
melting
56
Fig. 9. Spark erosion, absorbed power density
316 MW/m2, 1 ms, 100 shots, room temperature
5. CONCLUSIONS
The damage threshold and the failure mechanism of
tungsten coatings under transient fusion relevant heat
loads were characterised in an electron beam facility. The
delamination of the coating is mainly dependent on the
absorbed power density. Only a very small influence of
temperature can be observed. The parallel fiber
orientation of the CFC substrate is the preferred region to
start the delamination of the coating due to the bad
thermal conductivity and the high mismatch in thermal
expansion between the coating and the substrate.
ACKNOWLEDGEMENTS
We acknowledge G. Knauf, G. Böling, T. Flossdorf,
E. Wessel, M. Diederichs, M. Hühnerbein and M. Wirtz
for their assistance with the experiments and
investigations.
This work, supported by the European Communities
under the contract of Association between
EURATOM/Forschungszentrum Jülich, was carried out
within the framework of the European Fusion
Development Agreement. The views and opinions
expressed herein do not necessarily reflect those of the
European Commission.
REFERENCES
1. C. Ruset, et al.// Fusion Engineering and Design. 2009,
v. 84, p. 1662.
Article received 13.09.10
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|
| id | nasplib_isofts_kiev_ua-123456789-17457 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T18:56:55Z |
| publishDate | 2010 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Thomser, C. Linke, J. Matthews, G. Riccardo, V. Schmidt, A. Vasechko, V. 2011-02-26T20:52:56Z 2011-02-26T20:52:56Z 2010 Tungsten coatings under fusion relevant heat loads / C. Thomser, J. Linke, G. Matthews, V. Riccardo, A. Schmidt, V. Vasechko // Вопросы атомной науки и техники. — 2010. — № 6. — С. 54-56. — Бібліогр.: 1 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/17457 Components for first wall applications in future nuclear fusion devices like ITER or DEMO need to fulfill special requirements. Especially transient thermal loads like Edge Localized Modes (ELMs) have a severe impact on the material damage. Tungsten coatings are being assessed for use instead of bulk tungsten. In order to quantify their material degradation, tungsten coatings on a fiber-reinforced graphite substrate were exposed to repeated short fusion relevant thermal pulses in an electron beam material test facility JUDITH 1 (Juelich Divertor Test Facility in Hot Cells). We acknowledge G. Knauf, G. Böling, T. Flossdorf, E. Wessel, M. Diederichs, M. Hühnerbein and M. Wirtz for their assistance with the experiments and investigations. This work, supported by the European Communities under the contract of Association between EURATOM/Forschungszentrum Jülich, was carried out within the framework of the European Fusion Development Agreement. The views and opinions expressed herein do not necessarily reflect those of the European Commission. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України ИТЭР и приложения для термоядерного реактора Tungsten coatings under fusion relevant heat loads Поведение вольфрамовых покрытий в условиях, имитирующих термоядерные тепловые нагрузки Article published earlier |
| spellingShingle | Tungsten coatings under fusion relevant heat loads Thomser, C. Linke, J. Matthews, G. Riccardo, V. Schmidt, A. Vasechko, V. ИТЭР и приложения для термоядерного реактора |
| title | Tungsten coatings under fusion relevant heat loads |
| title_alt | Поведение вольфрамовых покрытий в условиях, имитирующих термоядерные тепловые нагрузки |
| title_full | Tungsten coatings under fusion relevant heat loads |
| title_fullStr | Tungsten coatings under fusion relevant heat loads |
| title_full_unstemmed | Tungsten coatings under fusion relevant heat loads |
| title_short | Tungsten coatings under fusion relevant heat loads |
| title_sort | tungsten coatings under fusion relevant heat loads |
| topic | ИТЭР и приложения для термоядерного реактора |
| topic_facet | ИТЭР и приложения для термоядерного реактора |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/17457 |
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