Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns
The paper presents the results of studies of the effect of ion-plasma treatment of copper surfaces on their resistance to high-vacuum breakdowns. It has been experimentally shown that the plasma and ion-beam modification of the copper surface leads to an increase of the breakdown voltage from 5 to...
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irk-123456789-1476632019-02-16T01:25:35Z Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns Baturin, V.A. Karpenko, A.Yu. Storizhko, V.Е. Shutko, V.A. Приложения и технологии The paper presents the results of studies of the effect of ion-plasma treatment of copper surfaces on their resistance to high-vacuum breakdowns. It has been experimentally shown that the plasma and ion-beam modification of the copper surface leads to an increase of the breakdown voltage from 5 to 35%, depending on the modification method, and reduces the dark current of the anode-cathode. Представлено результати досліджень впливу іонно-плазмової обробки поверхні міді на її стійкість до високо вакуумних пробоїв. Експериментально показано, що плазмова та іонно-променева модифікації поверхні міді призводять до збільшення пробивної напруги від 5 до 35%, в залежності від методу модифікації, та зменшення темного струму анодного катода. Представлены результаты исследований влияния ионно-плазменной обработки поверхности меди на её сопротивление сильным вакуумным пробоям. Экспериментально показано, что плазменная и ионно-лучевая модификации поверхности меди приводят к увеличению пробивного напряжения от 5 до 35%, в зависимости от метода модификации, и уменьшению темного тока анодного катода. 2018 Article Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns / V.A. Baturin, A.Yu. Karpenko, V.Е. Storizhko, V.A. Shutko // Вопросы атомной науки и техники. — 2018. — № 4. — С. 297-301. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 52.80.Mg; 52.80.Vp http://dspace.nbuv.gov.ua/handle/123456789/147663 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Приложения и технологии Приложения и технологии |
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Приложения и технологии Приложения и технологии Baturin, V.A. Karpenko, A.Yu. Storizhko, V.Е. Shutko, V.A. Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns Вопросы атомной науки и техники |
| description |
The paper presents the results of studies of the effect of ion-plasma treatment of copper surfaces on their resistance to high-vacuum breakdowns. It has been experimentally shown that the plasma and ion-beam modification
of the copper surface leads to an increase of the breakdown voltage from 5 to 35%, depending on the modification
method, and reduces the dark current of the anode-cathode. |
| format |
Article |
| author |
Baturin, V.A. Karpenko, A.Yu. Storizhko, V.Е. Shutko, V.A. |
| author_facet |
Baturin, V.A. Karpenko, A.Yu. Storizhko, V.Е. Shutko, V.A. |
| author_sort |
Baturin, V.A. |
| title |
Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns |
| title_short |
Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns |
| title_full |
Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns |
| title_fullStr |
Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns |
| title_full_unstemmed |
Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns |
| title_sort |
investigation of copper samples with ion-plasma treatment on the high voltage breakdowns |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2018 |
| topic_facet |
Приложения и технологии |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/147663 |
| citation_txt |
Investigation of copper samples with ion-plasma treatment on the high voltage breakdowns / V.A. Baturin, A.Yu. Karpenko, V.Е. Storizhko, V.A. Shutko // Вопросы атомной науки и техники. — 2018. — № 4. — С. 297-301. — Бібліогр.: 5 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-07-11T02:36:03Z |
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2025-07-11T02:36:03Z |
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1837316312523603968 |
| fulltext |
ISSN 1562-6016. ВАНТ. 2018. №4(116) 297
INVESTIGATION OF COPPER SAMPLES WITH ION-PLASMA
TREATMENT ON THE HIGH VOLTAGE BREAKDOWNS
V.A. Baturin, A.Yu. Karpenko, V.Е. Storizhko, V.A. Shutko
Institute of Applied Physics, National Academy of Sciences of Ukraine, Sumy, Ukraine
E-mail: baturin49@gmail.com, ayk@ukr.net
The paper presents the results of studies of the effect of ion-plasma treatment of copper surfaces on their re-
sistance to high-vacuum breakdowns. It has been experimentally shown that the plasma and ion-beam modification
of the copper surface leads to an increase of the breakdown voltage from 5 to 35%, depending on the modification
method, and reduces the dark current of the anode-cathode.
PACS: 52.80.Mg; 52.80.Vp
INTRODUCTION
The current state of high-energy physics requires the
creation of accelerators of a new generation with a high
rate of acceleration. Important factors limiting the rate
of acceleration are auto-emission loads on accelerating
structures and vacuum breakdowns. In particular, one of
the main tasks of the CLIC project (Compact LInear
Collider), being designed at CERN (European signing
center), is the creation of accelerating structures with a
record acceleration rate (more than 100 MV/m). In or-
der to ensure the operation of the CLIC and the acceler-
ation rate of 100 MV/m, it is intended that the probabil-
ity of breakdowns should not exceed 10-7 1/m. Because
each breakdown leads to loss of the beam and damage
to the accelerating structures, various methods are being
investigated ensuring the stability of accelerating struc-
tures to high-voltage breakdowns.
Therefore, it is actual the creating and studying the
properties of construction materials, which could have
the characteristics needed for accelerating structures at
the higher work function. One of the way to decrease
the breakdown rate in vacuum devices can be work
function increasing and, consequently, the breakdown
field increasing. The surface modification can be one of
the way for this aim.
According to this, it is actual to study the pre-
breakdown and breakdown processes to improve the
understanding of phenomena and to select the optimal
material for electrodes used in vacuum devices and par-
ticle accelerators. During recent years, the Institute of
Applied Physics National Academy of Sciences of
Ukraine (IAP NASU) is a member of CLIC (Compact
Linear Collider) collaboration at CERN (European Or-
ganization for Nuclear Research). The main direction of
join research is to determinate the influence of various
factors to breakdown probability in the high gradient
electrical fields.
For these goals, there were special special experi-
mental stands at the IAP NASU and at CERN [1, 2]. In
the CERN was focused on research of high-voltage
conditioning of materials for accelerating structures. In
the IPF, the study of the influence of ion-beam and
plasma modification of the surface of copper samples on
the conditions for the onset and development of high-
voltage breakdown was the main research direction.
EXPERIMENTAL STAND IAP
The results presented here obtained on an experi-
mental stand IAP [1].
The experimental setup includes the following ele-
ments: vacuum chamber with samples and monopole
mass-spectrometer for as RGA (Residual Gas Analyzer)
in the vacuum chamber; the system for pre-breakdown
current and breakdown registration; the system for vac-
uum chamber and sample heating; the power supplies;
the vacuum pumping system and the equipment for sys-
tem operation.
The vacuum system design provides the necessary
pressure in the different parts of the setup at the prepara-
tion step and during experiment process. To minimize
the influence of vacuum conditions to breakdown pro-
cess, the pressure is reached not less than 10-7 Pa in the
vacuum chamber.
The test samples are placed in the high-vacuum
chamber. It has the reciprocating mechanical feed-
through. It is located at the upper flange and allows
changing the distance between the electrodes. The bot-
tom flange includes a high-vacuum inlet for a high volt-
age apply to the cathode. The side flanges are used as
windows for visual observation of internal volume of
the vacuum chamber and measuring current leads. The
sample is fixed at the electrode and can be heating up to
400oC for outgassing. The additional chamber with the
monopole mass spectrometer connected to the working
chamber.
The electrodes of the discharge gap have tip-plane
configuration, and are located in the vacuum chamber.
The sample is mounted on the special holder used as
cathode. The size of the sample is 11 mm diameter and
2 mm thickness. The sample holder located on the stem
isolated from the walls of vacuum chamber. Though
high-voltage input (a metal-ceramic insulator), the high-
voltage with negative polarity is applied to the cathode.
The power supply allows for reached of electrical field
strength up to 500 MV/m. The anode has 2.5 mm diam-
eter and rounded end. Before measurement, the vacuum
chamber was heated during the day. The mass spec-
trometer made it possible to measure the mass spectrum
of gases in the vacuum chamber. The Ion current anode
cathode is measured with accuracy of 0.1 nA.
The discharge gap shown in Fig. 1.
https://mail.ukr.net/classic
mailto:ayk@ukr.net
ISSN 1562-6016. ВАНТ. 2018. №4(116) 298
Fig. 1. The cathode-holder with the sample
and anode in the vacuum chamber
PREPARATION OF THE SAMPLES
SURFACE
Samples of copper with a low content of impurities
were taken as materials for the experiments. The anode
was a tungsten rod. After the production of the samples,
the surface under investigation was subjected to me-
chanical grinding and polishing. Further, the samples
were subjected to a purification procedure, high-
temperature annealing in vacuum and treatment in a
glow discharge.
Three main types of copper samples were prepared:
1. Surface cleaning – polishing, annealing, cleaning
in glow discharge.
2. Ion-plasma coating – coating Ti, TiN, Mo films.
3. Ion implantation treatment.
Half of the sample was subjected to modification.
The second half remained unchanged. This made it pos-
sible to determine the effect of surface modification on
identical copper samples.
Ion-plasma treatment of copper samples was carried
out at the Institute of Applied Physics of the NAS of
Ukraine – high-frequency magnetron sputtering ВС-
350, and electron-beam device ELA-60. Ion-beam pro-
cessing of samples was carried out on the high-dose
implanter of the IAP NASU "Vesuvius-5", which allows
irradiating samples with both singly charged and multi-
ply charged ions with energies up to 300 keV.
Series of copper samples with coatings were irradi-
ated with Ar2+, Zr2+ and N+ ions with an energy of
300 keV. The radiation doses varied in the range
(1.2…4)⋅1017 cm-2.
Some of the copper samples were subjected to plas-
ma and ion-beam modification of the surface layer.
Since the frequency of 12 GHz will be used in the ac-
celerating structures of the CLIC (the thickness of the
skin layer for copper is 0.67 μm), the thickness of the
modified layer should not exceed 0.67 μm.
Tables 1 and 2 show modes plasma and ion modifi-
cation copper samples.
Table 1
Modes sputtering thin film coatings on copper samples
Number Spattering
samples Gas Coating Thinks coat-
ing, µm
1 Ti Ar,N TiN ~0.15
5 Ti Ar,N TiN ~ 0.15
6 Ti Ar,N TiN ~ 0.15
7 Ti Ar Ti ~ 0.2
8 Mo Ar Mo 0.08
9 Mo Ar Mo 0.08
10 Mo Ar Mo 0.4
Table 2
Modes of copper samples irradiation
EXPERIMENT
In all experiments, the discharge gap between the
cathode and the anode remained fixed and was 100 µm
with an accuracy of 5 µm. The value of the high voltage
gradually increased, creating a constant field in the dis-
charge gap with strength of 50 MV/m and higher up to
the occurrence of an irreversible breakdown process.
The value breakdown voltage for each sample of
was determined at several locations, to eliminate the
influence of the sample surface at which breakdown
occurs in previous experiments. For each sample, the
breakdown voltage was calculated from many meas-
urements.
DISCUSSION OF RESULTS
INFLUENCE OF ANNEALING AND CLEANING
Part of the copper samples passed the following pro-
cedure: polishing; heating in a high vacuum (10-5 Pa);
cleaning in a glow discharge of argon plasma.
Fig. 2 shows the histogram of the breakdown voltage
and the dependence of the dark current on the voltage
between the anode and cathode (Fig. 3) for copper sam-
ples with different surface treatments (vacuum 10-7 Pa).
Figs. 2 and 3 confirm the fact that the state of the
surface significantly affects the breakdown voltage. In
particular, it is seen that the annealing at 350°C increas-
es the breakdown voltage by 10%, and glow discharge
cleaning 20%. This is also confirmed by the dependence
of the dark current on the surface cleaning state.
Number Surface
composition Ions Ion energy,
кэВ
Dose,
1017cm-2
2 Cu Ar2+ 300 1.6
3 Cu Zr2+ 300 1.2
4 Cu N+ 150 4
5 TiN film Ar2+ 300 1.6
6 TiN film N+ 150 4
7 Ti film N+ 150 4
8 Mo film N+ 150 4
9 Mo film Ar2+ 300 1.6
10 Mo film Ar2+ 300 1.6
ISSN 1562-6016. ВАНТ. 2018. №4(116) 299
Fig. 2. Breakdown voltage for samples
with different surface cleaning
Fig. 3. Dark current for samples
with different surface cleaning
COPPER SAMPLES WITH ION PLASMA
COATING
Copper samples with thin coatings of metal films
with higher breakdown voltages than copper give a sta-
ble result of increasing the breakdown voltage (Fig. 4).
Fig. 4. Breakdown voltage for copper samples
with Mo, Ti, TiN coatings
With increasing thickness of the deposited thin film,
the breakdown voltage increases and probably ap-
proaching the breakdown voltage bulk sample of the
same composition. The data on breakdown voltages for
samples with thin films deposited correlate well with the
results of investigations for bulk samples (Fig. 5).
Coatings with Mo or Ti films increase the break-
down voltage by ~ 16%, and TiN by 20%.
On the surface of copper samples, various defects
can be centers of electron emission and stimulate dis-
charge [4]. It can be different inclusions on the surface
of the electrodes, grain boundaries, surface defects ob-
tained during its manufacture. In this case, the titanium
nitride film smooths and fills surface defects.
Fig. 5. Histogram of breakdown voltage for massive
samples of different materials [3]
Thin titanium nitride films on the copper surface can
behave as a barrier to the diffusion of gas from the cath-
ode volume.
In these studies, the anode was made of tungsten.
These conclusions are confirmed by a decrease in
the pre-breakdown current on samples coated with tita-
nium nitride, compared with copper samples (Fig. 6).
Fig. 6. Pre-breakdown currents for a sample
with a TiN films
In [5], the authors showed that the elements of the
accelerating structures covered with titanium nitride
have a smaller secondary emission of electrons com-
pared to uncoated samples (Fig. 7).
Fig. 7. Secondary electron emission coefficient
for stainless steel samples without are coated
and with coated of TiN [5]
The authors of this work have received not unam-
biguous results that require additional research in their
opinion, but in our case it is impossible not to exclude
such an effect.
ION IMPLANTATION
The results on the irradiation of copper samples by
Ar2+, N+, Zr2+ ions are shown in Figs. 8-10.
ISSN 1562-6016. ВАНТ. 2018. №4(116) 300
Fig. 8. The results of irradiation of samples
with Ar2+ ions
Irradiation of copper samples and samples with TiN
films of Ar2+ ions led to an increase in the breakdown
voltage. This is obviously related to the effects of dis-
placement of dissolved gas impurities from near-surface
layers by argon ions and smoothing of surface defects.
In contrast, for molybdenum films with different
thicknesses, the opposite effect is observed and the
breakdown voltage decreases. In this case, for a thinner
molybdenum film, the breakdown voltage becomes
lower than for a thicker one.
Additional studies of the surface of these samples
showed that the irradiation increases the defectiveness
of molybdenum films. This probably led to a decrease in
the breakdown voltage.
The best result of increase breakdown voltages
(35%) was obtained on copper with TiN coating and
additional irradiation with argon ions.
Fig. 9. The results of irradiation of samples
with N+ ions
The study of samples that were irradiated with N+
ions (see Fig. 9) showed a decrease of the breakdown
voltage. An exception was a sample with a Ti film on
copper. Irradiation of a titanium film with nitrogen ions
led to the formation of a thin near-surface layer of tita-
nium nitride, which apparently served as a diffusion
barrier, while on all other samples the incorporation of
nitrogen increased the probability of breakdown. It is
possible that the nitrogen dissolved in the near-surface
layers of the material can serve as one of the factors that
stimulate the breakdowns.
Implantation of Zr2+ ions increased the breakdown
voltage of the samples. This is evident from Fig. 10.
Fig. 10. The results of irradiation of samples
with Zr 2+ ions
Implantation of copper samples with Zr2+ ions also
leads to an increase of the breakdown voltage. In this
case, one can assume an effect for two reasons. On the
one hand, as in the case with argon, the displacement of
dissolved gases from the surface layers and the smooth-
ing of the surface occurs. On the other hand, the pres-
ence on the surface of particles of matter with a higher
breakdown voltage increases the resistance of copper
samples to breakdowns.
CONCLUSIONS
Plasma and ion-beam modifications of copper sam-
ples were performed to study their resistance to high
vacuum high-voltage breakdowns.
It has been experimentally shown that the plasma
and ion-beam modification of the copper surface leads
to an increase of the breakdown voltage from 5 to 35%,
depending on the modification method, and reduces the
dark current of the anode-cathode. The best result was
obtained on copper with TiN coating and additional
irradiation with argon ions (EAr2+ = 300 keV).
PLANS
In the next project, it is planned to continue these
studies − in particular, to determine in more detail the
optimal values of the thickness of the coating, and the
dose of irradiation. It is also important to focus on the
measurement of dark current, and its dependence on the
type of coating and dose of ion irradiation.
It is also important to investigate the dependence of
the breakdown voltage and dark current from the dis-
tance between the electrodes.
ACKNOWLEDGEMENTS
This work was supported by the target research pro-
gram of the NAS of Ukraine cooperation with CERN
and JINR ”Nuclear matter in extreme conditions” under
Contract ЦO-1-16/2017.
REFERENCES
1. V.A. Baturin, O.Yu. Karpenko, Ia.V. Profatilova,
S.O. Pustovoitov, V.I. Miroshnichenko. The experi-
mental setup for high voltage breakdown studies in
the high vacuum // Problems of Atomic Science and
Technology. Series “Plasma Electronics and New
Methods of Acceleration”. 2015, № 4, p. 294-297.
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2. Morten Kildemo. New spark-test device for material
characterization // Nuclear Instruments and Methods
in Physics Research. 2004, A 530, p. 596-606.
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University of Manchester for the degree of Doctor of
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5. O.S. Orlov, I.N. Mmeshkov, A.Yu. Rudakov,
A.V. Filipov // Pisma v EChAYa. 2014, v. 11,
№ 5(189), p. 981-985 (in Russian).
Article received 12.06.2018
ИССЛЕДОВАНИЕ ОБРАЗЦОВ МЕДИ С ИОННО-ПЛАЗМЕННОЙ ОБРАБОТКОЙ
НА ВЫСОКОВОЛЬТНЫЕ ПРОБОИ
В.А. Батурин, А.Ю. Карпенко, В.Е. Сторижко, В.А. Шутько
Представлены результаты исследований влияния ионно-плазменной обработки поверхности меди на её
сопротивление сильным вакуумным пробоям. Экспериментально показано, что плазменная и ионно-лучевая
модификации поверхности меди приводят к увеличению пробивного напряжения от 5 до 35%, в зависимо-
сти от метода модификации, и уменьшению темного тока анодного катода.
ДОСЛІДЖЕННЯ ЗРАЗКІВ МІДІ З ІОННО-ПЛАЗМОВОЮ ОБРОБКОЮ
НА ВИСОКОВОЛЬТНІ ПРОБОЇ
В.А. Батурін, О.Ю. Карпенко, В.Ю. Сторіжко, В.О. Шутько
Представлено результати досліджень впливу іонно-плазмової обробки поверхні міді на її стійкість до ви-
соко вакуумних пробоїв. Експериментально показано, що плазмова та іонно-променева модифікації поверх-
ні міді призводять до збільшення пробивної напруги від 5 до 35%, в залежності від методу модифікації, та
зменшення темного струму анодного катода.
ИССЛЕДОВАНИЕ ОБРАЗЦОВ МЕДИ С ИОНно-ПЛАЗМенной обработкой НА высоковольтные пробои
представлены результаты исследований влияния ионно-плазменной обработки поверхности меди на её сопротивление сильным вакуумным пробоям. Экспериментально показано, что плазменная и ионно-лучевая модификации поверхности меди приводят к увеличению пробив...
дослідження зразків міді з іонно-плазмовою обробкою на високовольтні пробої
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