Floating potential of dielectric target in plasma-beam discharge with magnet field
We present the results of investigations of the floating potential compensation of dielectric target in selfsustained plasma beam discharge in the magnetic field. We use gridless single-stage plasma accelerators with closed electron drift and narrow acceleration zone without of additional electron...
Збережено в:
| Опубліковано в: : | Вопросы атомной науки и техники |
|---|---|
| Дата: | 2006 |
| Автори: | , , , |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
2006
|
| Теми: | |
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/82469 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Floating potential of dielectric target in plasma-beam discharge with magnet field / A.M. Dobrovol`s`kii, A.N. Evsyukov, A.A. Goncharov, I.M. Protsenko // Вопросы атомной науки и техники. — 2006. — № 5. — С. 122-125. — Бібліогр.: 5 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-82469 |
|---|---|
| record_format |
dspace |
| spelling |
Dobrovol`s`kii, A.M. Evsyukov, A.N. Goncharov, A.A. Protsenko, I.M. 2015-05-31T06:28:59Z 2015-05-31T06:28:59Z 2006 Floating potential of dielectric target in plasma-beam discharge with magnet field / A.M. Dobrovol`s`kii, A.N. Evsyukov, A.A. Goncharov, I.M. Protsenko // Вопросы атомной науки и техники. — 2006. — № 5. — С. 122-125. — Бібліогр.: 5 назв. — англ. PACS: 52.80.-s https://nasplib.isofts.kiev.ua/handle/123456789/82469 We present the results of investigations of the floating potential compensation of dielectric target in selfsustained plasma beam discharge in the magnetic field. We use gridless single-stage plasma accelerators with closed electron drift and narrow acceleration zone without of additional electron emitter as plasma beam source. When the source of such type works in collimated beam mode, lack of electrons in the ion flow leads to occurrence of positive charge on the target and reduces the efficiency of ion treatment. Existence of additional glow discharge in beam drift space can influence on target potential. We discuss experimental results of measurement of dielectric target potential for different conditions and proposal to solve the problem. Мы представляем результаты исследований компенсации плавающего потенциала диэлектрической мишени в самосогласованном пучково-плазменном разряде в магнитном поле. Мы используем бессеточный одноступенчатый плазменный ускоритель с замкнутым дрейфом электронов и узкой зоной ускорения без дополнительного эмиттера электронов в качестве источника пучка плазмы. Когда источник такого типа работает в режиме коллимированного пучка, недостаток электронов в ионном потоке ведет к возникновению положительного заряда на мишени и уменьшает эффективность ионной обработки. Существование дополнительного тлеющего разряда в пространстве дрейфа пучка может влиять на потенциал мишени. Мы обсуждаем экспериментальные результаты измерения потенциала диэлектрической мишени для различных условий и предлагаем решение проблемы. Ми представляємо результати досліджень компенсації плаваючого потенціалу діелектричної мішені у самоузгодженому пучково-плазмовому розряді у магнітному полі. Ми використовуємо безсітковий одно ступеневий плазмовий прискорювач з замкнутим дрейфом електронів та вузькою зоною прискорення без додаткового емітера електронів як джерело пучка плазми. Коли джерело такого типу працює в режимі колимованого пучка, недолік електронів у іонному потоці веде до виникнення позитивного заряду на мішені та зменшує ефективність іонної обробки. Існування додаткового жевріючого розряду у просторі дрейфу пучка може впливати на потенціал мішені. Ми обговорюємо експериментальні результати вимірювань потенціалу діелектричної мішені для різних умов та пропонуємо розв’язок проблеми. en Вопросы атомной науки и техники Газовый разряд, плазменно-пучковый разряд Floating potential of dielectric target in plasma-beam discharge with magnet field Плавающий потенциал диэлектрической мишени в пучково-плазменном разряде с магнитным полем Плаваючий потенціал діелектричної мішені у пучково-плазмовому розряді з магнітним полем Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Floating potential of dielectric target in plasma-beam discharge with magnet field |
| spellingShingle |
Floating potential of dielectric target in plasma-beam discharge with magnet field Dobrovol`s`kii, A.M. Evsyukov, A.N. Goncharov, A.A. Protsenko, I.M. Газовый разряд, плазменно-пучковый разряд |
| title_short |
Floating potential of dielectric target in plasma-beam discharge with magnet field |
| title_full |
Floating potential of dielectric target in plasma-beam discharge with magnet field |
| title_fullStr |
Floating potential of dielectric target in plasma-beam discharge with magnet field |
| title_full_unstemmed |
Floating potential of dielectric target in plasma-beam discharge with magnet field |
| title_sort |
floating potential of dielectric target in plasma-beam discharge with magnet field |
| author |
Dobrovol`s`kii, A.M. Evsyukov, A.N. Goncharov, A.A. Protsenko, I.M. |
| author_facet |
Dobrovol`s`kii, A.M. Evsyukov, A.N. Goncharov, A.A. Protsenko, I.M. |
| topic |
Газовый разряд, плазменно-пучковый разряд |
| topic_facet |
Газовый разряд, плазменно-пучковый разряд |
| publishDate |
2006 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| format |
Article |
| title_alt |
Плавающий потенциал диэлектрической мишени в пучково-плазменном разряде с магнитным полем Плаваючий потенціал діелектричної мішені у пучково-плазмовому розряді з магнітним полем |
| description |
We present the results of investigations of the floating potential compensation of dielectric target in
selfsustained plasma beam discharge in the magnetic field. We use gridless single-stage plasma accelerators with
closed electron drift and narrow acceleration zone without of additional electron emitter as plasma beam source.
When the source of such type works in collimated beam mode, lack of electrons in the ion flow leads to occurrence
of positive charge on the target and reduces the efficiency of ion treatment. Existence of additional glow discharge in
beam drift space can influence on target potential. We discuss experimental results of measurement of dielectric
target potential for different conditions and proposal to solve the problem.
Мы представляем результаты исследований компенсации плавающего потенциала диэлектрической
мишени в самосогласованном пучково-плазменном разряде в магнитном поле. Мы используем бессеточный
одноступенчатый плазменный ускоритель с замкнутым дрейфом электронов и узкой зоной ускорения без
дополнительного эмиттера электронов в качестве источника пучка плазмы. Когда источник такого типа
работает в режиме коллимированного пучка, недостаток электронов в ионном потоке ведет к возникновению
положительного заряда на мишени и уменьшает эффективность ионной обработки. Существование
дополнительного тлеющего разряда в пространстве дрейфа пучка может влиять на потенциал мишени. Мы
обсуждаем экспериментальные результаты измерения потенциала диэлектрической мишени для различных
условий и предлагаем решение проблемы.
Ми представляємо результати досліджень компенсації плаваючого потенціалу діелектричної мішені у
самоузгодженому пучково-плазмовому розряді у магнітному полі. Ми використовуємо безсітковий одно
ступеневий плазмовий прискорювач з замкнутим дрейфом електронів та вузькою зоною прискорення без
додаткового емітера електронів як джерело пучка плазми. Коли джерело такого типу працює в режимі
колимованого пучка, недолік електронів у іонному потоці веде до виникнення позитивного заряду на мішені
та зменшує ефективність іонної обробки. Існування додаткового жевріючого розряду у просторі дрейфу
пучка може впливати на потенціал мішені. Ми обговорюємо експериментальні результати вимірювань
потенціалу діелектричної мішені для різних умов та пропонуємо розв’язок проблеми.
|
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/82469 |
| citation_txt |
Floating potential of dielectric target in plasma-beam discharge with magnet field / A.M. Dobrovol`s`kii, A.N. Evsyukov, A.A. Goncharov, I.M. Protsenko // Вопросы атомной науки и техники. — 2006. — № 5. — С. 122-125. — Бібліогр.: 5 назв. — англ. |
| work_keys_str_mv |
AT dobrovolskiiam floatingpotentialofdielectrictargetinplasmabeamdischargewithmagnetfield AT evsyukovan floatingpotentialofdielectrictargetinplasmabeamdischargewithmagnetfield AT goncharovaa floatingpotentialofdielectrictargetinplasmabeamdischargewithmagnetfield AT protsenkoim floatingpotentialofdielectrictargetinplasmabeamdischargewithmagnetfield AT dobrovolskiiam plavaûŝiipotencialdiélektričeskoimišenivpučkovoplazmennomrazrâdesmagnitnympolem AT evsyukovan plavaûŝiipotencialdiélektričeskoimišenivpučkovoplazmennomrazrâdesmagnitnympolem AT goncharovaa plavaûŝiipotencialdiélektričeskoimišenivpučkovoplazmennomrazrâdesmagnitnympolem AT protsenkoim plavaûŝiipotencialdiélektričeskoimišenivpučkovoplazmennomrazrâdesmagnitnympolem AT dobrovolskiiam plavaûčiipotencíaldíelektričnoímíšeníupučkovoplazmovomurozrâdízmagnítnimpolem AT evsyukovan plavaûčiipotencíaldíelektričnoímíšeníupučkovoplazmovomurozrâdízmagnítnimpolem AT goncharovaa plavaûčiipotencíaldíelektričnoímíšeníupučkovoplazmovomurozrâdízmagnítnimpolem AT protsenkoim plavaûčiipotencíaldíelektričnoímíšeníupučkovoplazmovomurozrâdízmagnítnimpolem |
| first_indexed |
2025-11-25T23:07:23Z |
| last_indexed |
2025-11-25T23:07:23Z |
| _version_ |
1850578057935454208 |
| fulltext |
FLOATING POTENTIAL OF DIELECTRIC TARGET IN PLASMA-BEAM
DISCHARGE WITH MAGNET FIELD
A.M. Dobrovol`s`kii, A.N. Evsyukov, A.A. Goncharov, I.M. Protsenko
Institute of Physics of NASU, pr. Nauki 46, Kyiv 03028, Ukraine
E-mail: dobr@iop.kiev.ua
We present the results of investigations of the floating potential compensation of dielectric target in
selfsustained plasma beam discharge in the magnetic field. We use gridless single-stage plasma accelerators with
closed electron drift and narrow acceleration zone without of additional electron emitter as plasma beam source.
When the source of such type works in collimated beam mode, lack of electrons in the ion flow leads to occurrence
of positive charge on the target and reduces the efficiency of ion treatment. Existence of additional glow discharge in
beam drift space can influence on target potential. We discuss experimental results of measurement of dielectric
target potential for different conditions and proposal to solve the problem.
PACS: 52.80.-s
1. INTRODUCTION
Modern plasma technologies allow obtaining the
modification of surface and volume properties of
materials in a very wide range [1]. In some cases these
technologies operate with plasma-beam discharges and
dielectric targets. The production of ion-plasma beam is
possible by different types of ion or plasma sources.
Usually, the design of such type of the source includes
additional electrons source. Mainly the simple hot
filament or complicated hollow cathode is used as
additional electrons source. However, there exist
situations when this is unusable. And sources of
additional electrons of the other types either are
complex in operation, or have high prices (or are
subjected to both of those issues).
Of those, single-stage plasma accelerators with closed
electron drift and narrow acceleration zone (accelerator
with anode layer, AAL) excel from other plasma sources
by the simplicity of their design. Additionally, use of
accelerator with anode layer as a plasma flow source
solves the problem of low conductivity of the target
material. Efficient treatment by the plasma flow is
possible even for dielectric materials in vacuum mode of
AAL without electrons source [2].
In case of treatment of dielectric target by AAL
without electron emitter in vacuum mode the target will
have certain potential. The problem occurs due to lack
of electrons in the ion flow, and it leads to occurrence of
positive charge on the target and reduces the efficiency
of ion treatment. Use of additional glow discharges in
space between a source and a target allows essential
reducing of the potential of processed dielectric target
[3]. For obtaining the best conditions of target
processing, the careful optimization of conditions of
existence of such plasma-beam discharge is necessary.
2. EXPERIMENTAL SETUP
The experiments are carried out with single-stage
plasma accelerators with closed electron drift and
narrow acceleration zone of coaxial geometry without
additional electron emitter. Accelerator has the ring
discharge channel with width 10 mm, as it was
described in [3]. The principle scheme of the
experiments is shown in the Fig.1. The multilayer
current coil (3) is coaxial with the accelerator main axis
and allows variation of magnetic field distribution in the
source-target space. The power supply of the coil allows
change of the direction of magnetic induction vector to
opposite one. The plasma source power supply allows
use of the anode voltage of up to 2,5 kV. The usual
discharge current is less then 500 mA. Distance from
the source front to dielectric target is about 160 mm.
The floating potential was measured in the different
points of the vacuum volume with the use of a mobile
plane Langmuir probe (4) and thin metal collector (5)
by capacitive voltmeter.
3. RESULTS
The gridless plasma source of AAL type can work
either in collimated or diffuse beam mode [4]. In diffuse
beam mode glow discharge with current equivalent to
current of main discharge exists around the source [5].
The ion flow propagates from this discharge region to
the source cathode and sputters the cathode material.
The particles from the cathode can contaminate the
substrate surface and break the technological process
[4]. So we investigate the dielectric target potential for
collimated beam mode of source work.
Fig.1. Functional scheme of the experiments.
1 – source, 2 – plasma flow, 3 – current coil, 4 – mobile
probe, 5 – metal collector, 6 – target
The magnetic field is the inseparable component of
devices with the closed electrons drift. Usually,
magnetic systems of technological ALA are built on
permanent magnets, and the necessary configuration of
a field in a discharge gap is set by a choice of the form
of pole tips. Thus the part of magnetic field falls outside
of pole tips volume and the diffuse magnetic field exists
_______________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2006. № 5.
Серия: Плазменная электроника и новые методы ускорения (5), с.122-125.122
around of the source with a complex enough
configuration. On a basis of such magnetic system it is
possible to obtain two configurations of magnetic lines
above an obverse surface of the source. The first one
corresponds to a case of field of balanced magnetron and
the second one – to unbalanced magnetron. In the first
case, passing of electrons from a zone of existence of the
discharge to a target is essentially limited by the field
configuration, and in the second case there are magnetic
lines connecting the cathode of the accelerator with a
target. In the second case it is possible to expect more
complete compensation of the potential of dielectric
target, and consequently the magnetic system of source is
constructed so that a configuration close to the case of
unbalanced magnetron is reached in the space of drift.
a)
b)
Fig.2. The magnetic field map of plasma source
obtained experimentally. a) - from measurement with
Hall unit (µWb); b) – field is mapped using an iron
powder technique
Fig.2 shows the magnetic field maps obtained with
iron powder technique (b) and from measurement of
magnetic field above the accelerator with Hall unit and
the subsequent construction of corresponding magnetic
field map (a). One can see from the figure that the field
above a source can be divided in two areas. In the first
one, lines of a magnetic field go from a source to a
target, so that they will not block a compensation of
potential by free electrons. In the second case, the lines
look like arcs closed on cathodes, so that electrons will
have to overcome a confined magnetic field in addition
to a weak electric one which is set by the anode
potential. Earlier we already wrote about existence of
additional discharges in these diffuse fields [5]. It is
obviously important to check up the contribution of
each of the components of formed plasma-beam system
to the process of target potential compensation.
Fig.3. The changes of magnetic field map of plasma
sources with changes of coil current (µWb).
a – additional magnetic field in coil is additive to
source field, current – 2,5 A; b -- additional field is also
additive, current – 1 A; c -- additional field is opposite
_______________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2006. № 5.
Серия: Плазменная электроника и новые методы ускорения (5), с.122-125.123
to source field, current – 1 A, d -- additional field is
also opposite to source field, current – 2 A
a)
b)
Fig.4. The dependencies of floating potential of
dielectric target on different magnetic field distribution
for different pressure. a) diagram of float potential
value at coil current and pressure plane; b) Target
potential vs coil current, 1 – 0.1 mTorr; 2 – 0.5 mTorr;
3 – 0.9 mTorr; 4 – 1.2 mTorr; 5 – 1.4 mTorr
Current coil located coaxially with a source in space of
beam drift allows conducting of respective experiments.
Field of the coil allows change of the geometry of
mixed magnetic field in wide enough range. As one can
see from Fig.3, it allows stretching the second zone to
area of placement of the target and it to move it
significantly from the target to a plane of the source. For
convenience, we`ll designate the situation of addition of
fields of the coil and the source as "direct" insertion,
and a situation of subtraction of the fields as "opposite"
one. In case of direct insertion, we shall consider a
current in coil Icl as a positive, and the opposite one as a
negative. It is shown that value of diffuse field is small
enough, and in case of formation of discharge plasma in
this area it should provide small influence on the results.
Results of measurement of the floating potential of
target Ufl in case of direct and opposite insertion of the
coil are shown in Fig.4.
In Fig.4 the three-dimensional diagram (a) showing
dependence of a potential of the target on a pressure in
the chamber and a current in the coil and some its cross
sections by plane Ufl(Icl) (b) is presented. It is shown
that in case of low enough pressure (curves with
a)
b)
Fig.5.The dependencies of floating potential of dielectric
target for different pressure in vacuum chamber on radial
spacing from the main axis of system. a) diagram of
floating potential value on radius and pressure plane;
b) Target potential vs radius, 1 –0.3 mTorr;
2 – 0.5 mTorr; 3 – 0.9 mTorr; 4 – 1.2 mTorr; 5 – 1.4 mTorr
numbers 1 to 3) change of geometry of magnetic field
results in a small change of the target potential. But in
case of absence of the glow discharge in space of the
drift, the situation improves with distribution of a zone
of arc type to the target region. And with the advent of
the additional discharge in space of the drift, the
situation becomes an opposite (curves with numbers 3-
5). It can be easily explained considering fact that at low
pressure the electrons are generated mainly in the area
of anode layer, and with the advent of additional
discharge their significant quantity appears in the first
area of magnetic field. Simplification of their coming
onto the target considerably lowers its potential.
At the same time, one can see that with the further
growth of pressure the potential of a target becomes
rather significant again. Simultaneously, the additional
discharge fills the whole vacuum chamber, and a plasma
source switches to the diffuse beam mode. In this
situation the target potential becomes almost equal to
the anode one, and efficiency of cleaning of the target
124
decreases dramatically.
In Fig.5 the three-dimensional diagram showing
distribution of the floating potential in volume of the
chamber in dependence on pressure in the chamber and
distances from an axis of the system (a) and some its
sections by plane Ufl(r) is presented (b). One can see
that with the pressure increase a stage comes when the
potential is leveled on the chamber volume. The
dielectric target appears immersed in plasma of a
positive column of the glow discharge and gets the
corresponding floating potential, which can be below
the anode one only by a value of about kTe. Due to fact
that for this discharge the anode is that of the source, the
target potential appears comparable with the anode one.
CONCLUSIONS
One can see from the presented results that presence
of magnetic field in a volume of the discharge
influences value of the floating potential of a dielectric
target contacting with such plasma-beam discharge.
Both size and geometry of a magnetic field provide the
influences. In conditions of low pressure (below
1 mTorr) the target placement in the second area linked
to the anode layer and magnet field lines of arc type
closed on cathodes is preferable. In the pressure range
of about 1 mTorr and above, the target placement in a
zone, which is isolated from the anode layer by
magnetic field and does not limit pass of free electrons
onto the target, is preferable. For obtaining as low as
possible potential on a dielectric target in the range of
low vacuum it is important to provide its isolation from
plasma of the additional glow discharge arising in space
of a beam drift. Otherwise, the target appears immersed
in plasma of the high-voltage glow discharge and gets
the corresponding floating potential.
Thus, providing compensation of a dielectric target
potential in the pressure range of 1…10 mTorr with the
use of plasma-beam discharge is possible only if one
will not allow contact between the glow discharge
plasma and the target.
REFERENCES
1. V.M. Astashynski et al. Materials surface
modification using quasi-stationary plasma
accelerators // Surface and Coatings Technology.
2004, 180-181, p.392-395.
2. A. Goncharov et al. Plasma Devices for Ion Beam
and Plasma Deposition Applications // Problems of
Atomic Science and Technology. Series: Plasma
Physics (10). 2005, №1, p.169-171.
3. A.N. Dobrovol`s`kii, A.A. Goncharov, S.N. Pavlov,
O.A. Panchenko, I.M. Protsenko. Modernized
technological accelerator with anode layer for ion
cleaning // Problems of Atomic Science and
Technology. Series: Plasma Physics(7). 2002, №4,
p.176-178.
4. A.A. Goncharov, A.N. Dobrovolskiy, S.N. Pavlov,
O.A. Panchenko, Protsenko I.M. Technological
accelerator with closed electron drift for surface
treatment // Problems of Atomic Science and
Technology. Series: Plasma Physics (6). 2000, №6,
p.160-162.
5. S.N. Pavlov, A.A. Goncharov, A.N. Dobrovolsky,
I.M. Protsenko. Peculiarities of self-sustained
discharge in closed electron drift accelerator based
on permanent magnets // Problems of Atomic
Science and Technology. Series: Plasma Physics
(8). 2002, №5, p.133-135.
ПЛАВАЮЩИЙ ПОТЕНЦИАЛ ДИЭЛЕКТРИЧЕСКОЙ МИШЕНИ В ПУЧКОВО-ПЛАЗМЕННОМ
РАЗРЯДЕ С МАГНИТНЫМ ПОЛЕМ
A.Н. Добровольский, A.Н. Евсюков, A.A. Гончаров, И.M. Проценко
Мы представляем результаты исследований компенсации плавающего потенциала диэлектрической
мишени в самосогласованном пучково-плазменном разряде в магнитном поле. Мы используем бессеточный
одноступенчатый плазменный ускоритель с замкнутым дрейфом электронов и узкой зоной ускорения без
дополнительного эмиттера электронов в качестве источника пучка плазмы. Когда источник такого типа
работает в режиме коллимированного пучка, недостаток электронов в ионном потоке ведет к возникновению
положительного заряда на мишени и уменьшает эффективность ионной обработки. Существование
дополнительного тлеющего разряда в пространстве дрейфа пучка может влиять на потенциал мишени. Мы
обсуждаем экспериментальные результаты измерения потенциала диэлектрической мишени для различных
условий и предлагаем решение проблемы.
ПЛАВАЮЧИЙ ПОТЕНЦІАЛ ДІЕЛЕКТРИЧНОЇ МІШЕНІ У ПУЧКОВО-ПЛАЗМОВОМУ РОЗРЯДІ
З МАГНІТНИМ ПОЛЕМ
A.М. Добровольський, A.Н. Євсюков, О.A. Гончаров, І.M. Проценко
Ми представляємо результати досліджень компенсації плаваючого потенціалу діелектричної мішені у
самоузгодженому пучково-плазмовому розряді у магнітному полі. Ми використовуємо безсітковий одно
ступеневий плазмовий прискорювач з замкнутим дрейфом електронів та вузькою зоною прискорення без
додаткового емітера електронів як джерело пучка плазми. Коли джерело такого типу працює в режимі
колимованого пучка, недолік електронів у іонному потоці веде до виникнення позитивного заряду на мішені
та зменшує ефективність іонної обробки. Існування додаткового жевріючого розряду у просторі дрейфу
пучка може впливати на потенціал мішені. Ми обговорюємо експериментальні результати вимірювань
потенціалу діелектричної мішені для різних умов та пропонуємо розв’язок проблеми.
_______________________________________________________________
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2006. № 5.
Серия: Плазменная электроника и новые методы ускорения (5), с.122-125.125
|