Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species
First experiments showed that simultaneous bombardment with fuel particles and impurities leads to synergistic effects, where the erosion rate of a material cannot be explained by superposition of the separate sputtering processes. For the study of these effects a new Dual Beam Experiment setup has...
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| Date: | 2005 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2005
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| Cite this: | Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species / I. Bizyukov, K. Krieger, N. Azarenkov // Вопросы атомной науки и техники. — 2005. — № 2. — С. 101-103. — Бібліогр.: 12 назв. — англ. |
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| author | Bizyukov, I. Krieger, K. Azarenkov, N. |
| author_facet | Bizyukov, I. Krieger, K. Azarenkov, N. |
| citation_txt | Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species / I. Bizyukov, K. Krieger, N. Azarenkov // Вопросы атомной науки и техники. — 2005. — № 2. — С. 101-103. — Бібліогр.: 12 назв. — англ. |
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| container_title | Вопросы атомной науки и техники |
| description | First experiments showed that simultaneous bombardment with fuel particles and impurities leads to synergistic effects, where the erosion rate of a material cannot be explained by superposition of the separate sputtering processes. For the study of these effects a new Dual Beam Experiment setup has been designed and assembled. This paper describes the design and the accessible range of experimental conditions.
Перші експерименти показали, що одночасне бомбардування ізотопами водню і частками домішок приводить до синергетичних ефектів, при яких ступінь ерозії матеріалів не може бути пояснений суперпозицією розпилю¬ вальних процесів. Для вивчення цих ефектів розроблена і змонтована нова двопроменева експериментальна установка. Ця стаття описує її конструкцію і доступні експериментальні можливості.
Первые эксперименты показали, что одновременная бомбардировка изотопами водорода и частицами примесей приводит к синергетическим эффектам, при которых степень эрозии материалов не может быть объяснена суперпозицией распылительных процессов. Для изучения этих эффектов разработана и смонтирована новая двух лучевая экспериментальная установка. Эта статья описывает ее конструкцию и доступные эксперимен¬ тальные возможности.
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| first_indexed | 2025-12-07T13:12:31Z |
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CAPABILITIES OF A NEW DUAL BEAM EXPERIMENT FOR SIMULTA
NEOUS IRRADIATION OF MATERIALS WITH TWO ION SPECIES
I. Bizyukov 1, K. Krieger 2, N. Azarenkov 1
1V.N. Karazin Kharkov National University, Department of Physics and Technologies, 31 Kur
chatov Ave., Kharkov 61108, Ukraine;
2Max-Planck-Institut fьr Plasmaphysik, EURATOM Association, BoltzmannstraЯe 2,
D-85748 Garching, Germany
First experiments showed that simultaneous bombardment with fuel particles and impurities leads to synergistic ef
fects, where the erosion rate of a material cannot be explained by superposition of the separate sputtering processes. For
the study of these effects a new Dual Beam Experiment setup has been designed and assembled. This paper describes
the design and the accessible range of experimental conditions.
PACS: 52.40.Hf
1. INTRODUCTION
All major design studies of future fusion research and
reactor devices employ tungsten as plasma-facing compo
nent at least in the divertor region (see, e.g. [1-3]) since in
general, the erosion rate for low-Z materials like carbon
or beryllium is far too high in a steady-state power pro
ducing device [1]. Additionally, the use of large area car
bon-based materials leads to excessive co-deposition of
tritium causing a considerable safety problem [4]. For
tungsten, tritium accumulation by co-deposition is not ex
pected to be a problem. High-Z materials offer the advan
tage of low sputtering yields as compared to low-Z mate
rials like beryllium or carbon, however, their potential of
radiative plasma cooling is considerably higher, and,
therefore, the maximum tolerable concentrations in the
plasma are correspondingly low. The W plasma concen
tration must for example stay below a limit of approxi
mately 2×10-5 for ignited fusion plasmas [5] to avoid ex
cessive energy losses due to the strong specific line radia
tion power of tungsten [6] in the respective plasma tem
perature range.
Results from the ASDEX-Upgrade W-divertor experi
ment show that the erosion of tungsten is dominated by
impurities where C, W and O are the most common
species and that the erosion yield as well as the transport
in the main chamber critically depend on the actual diver
tor plasma parameters [7]. The simultaneous bombard
ment of the W surface by hydrogen isotopes and impuri
ties, namely carbon and tungsten, leads to synergistic ef
fects with significantly different plasma-wall interaction
properties compared to the ones of pure hydrogen or pure
carbon bombardment. This process also leads to forma
tion of mixed surface layers with properties usually dif
ferent from the original wall material.
Laboratory experiments on simultaneous bombard
ment of high-Z materials with hydrogen isotopes and im
purity projectiles have been reported previously [8, 9].
The simplest way to produce such a flux is a discharge in
methane and irradiation of surfaces with CH3 radicals tak
ing into account that ratio of carbon to hydrogen flux is
1:3 [8]. The experimental results, particularly regarding
erosion yields, cannot be explained by the superposition
of processes resulting from mutually independent irradia
tion of tungsten with carbon and hydrogen.
The previous experiments clearly indicate that combi
nation of basic processes do not provide a complete pic
ture of plasma-wall interactions. With respect to fusion
devices, synergistic effects have a great impact on impuri
ty wall sources and lifetime of wall components, and,
therefore have to be considered for the selection of suit
able plasma facing materials. However, only a few partic
ular cases have been studied so far. Sputtering of wall ma
terial, particularly high-Z elements, by simultaneous bom
bardment with different species is a new field of research
that is of great relevance for development of future fusion
devices. Therefore, the new Dual Beam Experiment
(DBE) at IPP Garching has been designed for exploring a
wider parameter range. In addition, the new experiment
allows in-situ ion beam analysis of irradiated samples,
which provides information on the depth distribution of
deposited and implanted species. This provides essential
data, which were not available in previous experiments
where only the weight change of samples could be mea
sured. This paper describes the design and the accessible
range of experimental conditions provided by the experi
mental setup.
2. DESIGN OF THE DBE SETUP
For the detailed investigation of synergistic effects,
the equipment of the Dual Beam Experiment includes two
ion sources generating beams focused onto the same spot
at the target Each part of the setup can be pumped inde
pendently of one another and can be separated from the
target chamber by shutters.
The MeV Beam Line for ion beam analysis ( IBA)
An ion beam line connects the target chamber with a
3 MeV tandem accelerator that provides ion species for
different types of ion beam analysis. The beam line is
pumped independently by a turbo-molecular pump so that
the vacuum is always better than 10-7 mbar. It can be
sealed by two shutters when IBA is not required. Two
quadrupole magnet systems and a beam profile monitor
are used for fine adjustment of the high energy ion beam
trajectory. The high energy ion beam shares the beam
defining aperture system in the target chamber with the
low energy ion beam from the Duoplasmatron source.
The high energy ion beam is passed into the vacuum
Problems of Atomic Science and Technology. Series: Plasma Physics (11). 2005. № 2. P. 101-103 101
chamber through the 60-degree bending magnet of the
Duoplasmatron source, which has to be switched off dur
ing IBA measurements. In this operation mode the non-
deflected low energy ion beam is passing the magnet
chamber into a beam dump area.
The Duoplasmatron Ion Beam System (D-IBS)
The ion beam system is capable of producing hydro
gen isotope and noble gas (except helium) ion beams with
energies varying from 0.5 to 10 keV. The system includes
the duoplasmatron source, extraction gap, Einzel lens,
beam steerer assembly, beam drift tube and a double fo
cusing 0.5 Tesla 60-degree bending magnet with inclined
pole shoes and a curvature radius of 92 mm. Ions are
formed in the ion source and are extracted by the extrac
tion gap to the final beam energy with an energy spread
less than 25 eV. The filament used in the source is plat
inum gauze, and a barium carbonate solution is used for
increased electron emission. It has a lifetime of many
hundreds of hours. The beam focusing on the target posi
tion is realized by the Einzel lens and the 60-degree bend
ing magnet, which also provides energy/mass separation.
Fine positioning of the beam is performed by a steerer
plate assembly. It consists of two orthogonal pairs of de
flection plates mounted in a row to eliminate quadrupole
focusing effects.
The Cesium Sputter Ion Beam System (CS-IBS)
The Cesium Sputter ion beam system is capable of
providing a wide variety of negative heavy ions with en
ergies from 0.5 to 15 keV, which is, however, limited to
10 keV by the present voltage supply. Negatively charged
ions are formed in the ion source by sputtering of a target
by cesium ions. The ions are accelerated to ground poten
tial and emerge with an energy equal to the cathode volt
age and are then mass analysed by a 30-degree magnet.
The magnet is capable of separating high-Z elements (e.g.
mass 184 from mass 200) but the mass resolution is low
enough to pass most isotopes of a given element in order
to obtain maximum beam current. Its maximal magnetic
field strength is 0.88 Tesla and its radius of curvature is
25.4 cm.
The Target Chamber
The vacuum chamber contains the samples for irradi
ation fixed on a movable holder, surrounded by a Faraday
cup for precise measurement of the beam currents. Beam
positions on the target are defined by beam guiding tubes
with apertures at the chamber entrance and close to the
target respectively. The residual pressure in the vacuum
chamber during analysis is <5×10-7 mbar and during low
energy ion irradiation <2×10-6 mbar. The spot of the ana
lysing beam is located in the center of the irradiated area
avoiding intersection with non-uniformly eroded parts of
the surface. The following solid state detectors are used
currently for IBA: proton counter, RBS detectors under
165° and 105° scattering angle. To observe the temperat
ure of the samples a thermocouple is attached to the mov
able holder. To measure beam fluences the charge of the
beam is measured by a current integrator. Experimental
errors due to secondary electron emission can be correc
ted using the Faraday cup. The beam tube’s system of
apertures provides a diameter of the beam trace of 1.5 mm
on the target plane. To avid edge effects on IBA measure
ments the beam tube also includes a movable aperture
with a diameter of 1 mm that allows to decrease the dia
meter of the high energy beam area. Consequently, only
the uniformly irradiated region of the target is analyzed
by IBA and therefore only depth variations of the ele
mental concentrations need to be considered in contrast to
weight loss measurements where lateral variations of the
irradiation current density may lead to significant errors in
the results.
3. PERFORMANCE OF THE DBE SETUP
The characteristics of the ion beams were measured by
irradiating a-C:H films and then determining the beam
profile using optical microscopy and profilometry. A D3
ion beam is used since it provides the highest beam cur
rent and the lowest energy per deuterium atom at the same
accelerating voltage. The right side of the graph shows the
fluence that can be reached during one working day.
Thus, using D3 ion beam accelerated up to 9 keV the
achievable fluence is 1.4×1024 D/m2 that is sufficient for
studying the effects connected to sputtering of tungsten
and its D retention [10].
The cesium sputter ion beam system has been tested
with carbon negative ions since this impurity is the most
common in currently existing fusion devices. Because of
the principle of operation [11], the system has a time vari
able beam current. The total collected fluence of carbon
atoms is about 6×1022 C/m2 using single negative ions ac
celerated up to 5 keV. Increase of the C fluence and/or de
crease of the energy per atom is possible utilizing various
negative molecules of carbon up to C5ˉ. Other negative
ions of fusion relevant elements which can be obtained
using the source and their expected fluxes are listed in the
table. One should note that the time variation of the beam
current has not yet been fully investigated for every type
of negative ions.
The list of negative ion species produced by cesium sput
ter source and their expected fluxes (m-2s-1)
H 2⋅1017 56Fe 6⋅1016
9BeH 2⋅1016 58Ni 5⋅1017
BeO 1017 181TaH 2⋅1015
12C 1018 TaC 5⋅1016
O 1018 TaO2 1017
48TiH 1017 186W 1016
51VH 1016 184WC 2⋅1016
51VC 3⋅1016 WO3 2⋅1016
28Si 1018
Application of thin films as irradiated targets and IBA
opens new capabilities for the investigation of plasma-
surface interactions, which are not available by other
methods. Particularly, thin films of high-Z elements, espe
cially tungsten, are of interest. They have already shown
their suitability for such experiments [10]. Apart from D
diffusion and retention, usually the penetration depth of
plasma particles below the surface in the model experi
102
ments is several tens of nanometers. Thin films of high-Z
elements with a thickness up to 0.5 µm allow measure
ment of depth profiles of both low-Z and high-Z element
simultaneously by means of Rutherford back-scattering
spectroscopy (RBS) and D depth profiling by means of
nuclear reaction analysis (NRA). Erosion can be detected
as decrease of the film thickness. Since RBS measure
ments take usually only about ten minutes, it is possible to
measure the depth distribution of impurities depending on
fluence and to compare the obtained data with results of
simulation codes such as the TRIDYN program [12].
4. CONCLUSIONS
Utilization of IBA and experiments with thin films of
high-Z materials is a new approach for the investigation
of synergistic effects occuring under simultaneous bom
bardment of plasma facing elements with fuel particles
and impurities. At the same time, in these experiments us
ing IBA allows to obtain significantly more details on the
plasma-material interactions than in weight-loss measure
ments. Coupling all the advantages together, it may allow
to clarify synergistic mechanisms of erosion which do not
occur under bombardment with single species.
REFERENCES
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Mater. 1 (2001) 290-293.
2. D. Meade, et al. Mission and design of the fusion igni
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IAEA Conf. on Fusion Energy, Sorrento, Italy October,
2000. (CD-ROM), pp. IAEA-CN-77/FTP2/16, IAEA,
Vienna, 2001.
3. S. Nishio, et al. Conceptional design of advanced
steady-state tokamak reactor. // Proceedings of the 18th
Conf. on Fusion Energy, Sorrento, Italy October, 2000.
(CDROM), pp. IAEA-CN-77/FTP2/14, IAEA, Vienna,
2001.
4. G. Federici, et al.// J. Nucl. Mater. 266_/269 (1999) 14.
Upgrade Team // Nucl. Fusion, 40 (2000) 1441.
5. N. Peacock, R. Barnsley, N. Hawkes, K. Lawson, M.
O. Mullane. Diagnostics for Experimental Thermonu
clear Fusion Reactors. / Ed. P. Stott, G. Gorini, E.
Sidoni. Varenna (Italy), Plenum, New York, 1996, p.
291.
6. D. Post, R. Jensen, C. Tarter, et al. // At. Data Nucl.
Data Tables, 20 (1977) 397.
7. K. Krieger et al.// J. Nucl. Mater. 266 –269 (1999) 207.
8. K.Krieger, J.Roth. Synergistic effects by simultaneous
bombardment of tungsten with hydrogen and carbon.//
Journal of Nuclear Materials, 290-293 (2001) 107-111.
9. K.Schmid, J.Roth. Erosion of high-Z metals with typi
cal impurity ions. // Journal of Nuclear Materials 313 –
316 (2003) 302 –310.
10. I. Bizyukov, K. Krieger, N. Azarenkov, S. Levchuk,
Ch. Linsmeier. Formation of D inventories and struc
tural modifications by deuterium bombardment of tung
sten thin films. // Proceedings of 16th International Con
ference on Plasma-Surface Interactions, May 27-31,
2004, in press.
11. G.D. Alton // Nuclear Instruments and Methods in
Physics Research, B73 (1993) 221-288.
12. W. Moeller, W. Eckstein, J.P. Biersack // Comput.
Phys. Commun. 51 (1988) 355.
ВОЗМОЖНОСТИ НОВОГО ДВУХ ЛУЧЕВОГО ЭКСПЕРИМЕНТА ПО ОДНОВРЕМЕННОМУ ОБЛУ
ЧЕНИЮ МАТЕРИАЛОВ ДВУМЯ ВИДАМИ ИОНОВ
И. Бизюков, К. Кригер, Н. Азаренков
Первые эксперименты показали, что одновременная бомбардировка изотопами водорода и частицами примесей
приводит к синергетическим эффектам, при которых степень эрозии материалов не может быть объяснена
суперпозицией распылительных процессов. Для изучения этих эффектов разработана и смонтирована новая
двух лучевая экспериментальная установка. Эта статья описывает ее конструкцию и доступные эксперимен
тальные возможности.
МОЖЛИВОСТІ НОВОГО ДВОПРОМЕНЕВОГО ЕКСПЕРИМЕНТУ ПО ОДНОЧАСНОМУ
ОПРОМІНЕННЮ МАТЕРІАЛІВ ДВОМА ВИДАМИ ІОНІВ
І. Бизюков, К. Крігер, М. Азаренков
Перші експерименти показали, що одночасне бомбардування ізотопами водню і частками домішок приводить
до синергетичних ефектів, при яких ступінь ерозії матеріалів не може бути пояснений суперпозицією розпилю
вальних процесів. Для вивчення цих ефектів розроблена і змонтована нова двопроменева експериментальна
установка. Ця стаття описує її конструкцію і доступні експериментальні можливості.
103
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| id | nasplib_isofts_kiev_ua-123456789-79525 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T13:12:31Z |
| publishDate | 2005 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Bizyukov, I. Krieger, K. Azarenkov, N. 2015-04-02T18:36:09Z 2015-04-02T18:36:09Z 2005 Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species / I. Bizyukov, K. Krieger, N. Azarenkov // Вопросы атомной науки и техники. — 2005. — № 2. — С. 101-103. — Бібліогр.: 12 назв. — англ. 1562-6016 PACS: 52.40.Hf https://nasplib.isofts.kiev.ua/handle/123456789/79525 First experiments showed that simultaneous bombardment with fuel particles and impurities leads to synergistic effects, where the erosion rate of a material cannot be explained by superposition of the separate sputtering processes. For the study of these effects a new Dual Beam Experiment setup has been designed and assembled. This paper describes the design and the accessible range of experimental conditions. Перші експерименти показали, що одночасне бомбардування ізотопами водню і частками домішок приводить до синергетичних ефектів, при яких ступінь ерозії матеріалів не може бути пояснений суперпозицією розпилю¬ вальних процесів. Для вивчення цих ефектів розроблена і змонтована нова двопроменева експериментальна установка. Ця стаття описує її конструкцію і доступні експериментальні можливості. Первые эксперименты показали, что одновременная бомбардировка изотопами водорода и частицами примесей приводит к синергетическим эффектам, при которых степень эрозии материалов не может быть объяснена суперпозицией распылительных процессов. Для изучения этих эффектов разработана и смонтирована новая двух лучевая экспериментальная установка. Эта статья описывает ее конструкцию и доступные эксперимен¬ тальные возможности. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Plasma dynamics and plasma wall interaction Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species Можливості нового двопроменевого експерименту по одночасному опроміненню матеріалів двома видами іонів Возможности нового двух лучевого эксперимента по одновременному облу¬ чению материалов двумя видами ионов Article published earlier |
| spellingShingle | Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species Bizyukov, I. Krieger, K. Azarenkov, N. Plasma dynamics and plasma wall interaction |
| title | Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species |
| title_alt | Можливості нового двопроменевого експерименту по одночасному опроміненню матеріалів двома видами іонів Возможности нового двух лучевого эксперимента по одновременному облу¬ чению материалов двумя видами ионов |
| title_full | Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species |
| title_fullStr | Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species |
| title_full_unstemmed | Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species |
| title_short | Capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species |
| title_sort | capabilities of a new dual beam experiment for simutaneous irradiation of materials with two ion species |
| topic | Plasma dynamics and plasma wall interaction |
| topic_facet | Plasma dynamics and plasma wall interaction |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79525 |
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