Plasma of electric arc discharge between copper electrodes in a gas flow
Spectroscopy investigations of the thermal multicomponent plasma of the electric arc discharge between copper electrodes in carbon dioxide and argon flows were carried out. The technique of calculation of plasma equilibrium composition is discussed. The influence of hydrodynamic cooling of gas fl...
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irk-123456789-1109782017-01-08T03:03:15Z Plasma of electric arc discharge between copper electrodes in a gas flow Babich, I.L. Boretskij, V.F. Veklich, A.N. Low temperature plasma and plasma technologies Spectroscopy investigations of the thermal multicomponent plasma of the electric arc discharge between copper electrodes in carbon dioxide and argon flows were carried out. The technique of calculation of plasma equilibrium composition is discussed. The influence of hydrodynamic cooling of gas flow on the plasma state is estimated. It was assumed that the thermal dissociation of molecules of working gas play the key role in deviation from local thermodynamic equilibrium (LTE) in plasma. Спектроскопічними методами досліджено термічну багатокомпонентну плазму електродугового розряду між мідними електродами у потоках аргону та вуглекислого газу. Обговорюється методика розрахунку рівноважного складу плазми. Оцінений вплив гідродинамічного охолодження потоком газу на стан плазми. Припускається, що термічна дисоціація молекул робочого газу є основним механізмом відхилення від локальної термодинамічної рівноваги в плазмі. Спектроскопическими методами исследована термическая многокомпонентная плазма электродугового разряда между медными электродами в потоках аргона и углекислого газа. Обсуждается методика расчета равновесного состава плазмы. Оценено влияние гидродинамического охлаждения потоком газа на состояние плазмы. Предполагается, что термическая диссоциация молекул рабочего газа является основным механизмом отклонения от локального термодинамического равновесия в плазме. 2008 Article Plasma of electric arc discharge between copper electrodes in a gas flow / I.L. Babich, V.F. Boretskij, A.N. Veklich // Вопросы атомной науки и техники. — 2008. — № 6. — С. 171-173. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS: 51.30.+i, 52.70.-m http://dspace.nbuv.gov.ua/handle/123456789/110978 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Low temperature plasma and plasma technologies Low temperature plasma and plasma technologies |
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Low temperature plasma and plasma technologies Low temperature plasma and plasma technologies Babich, I.L. Boretskij, V.F. Veklich, A.N. Plasma of electric arc discharge between copper electrodes in a gas flow Вопросы атомной науки и техники |
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Spectroscopy investigations of the thermal multicomponent plasma of the electric arc discharge between copper electrodes in carbon dioxide and argon flows were carried out. The technique of calculation of plasma equilibrium composition is discussed. The influence of hydrodynamic cooling of gas flow on the plasma state is estimated. It was assumed that the thermal dissociation of molecules of working gas play the key role in deviation from local thermodynamic equilibrium (LTE) in plasma. |
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Babich, I.L. Boretskij, V.F. Veklich, A.N. |
| author_facet |
Babich, I.L. Boretskij, V.F. Veklich, A.N. |
| author_sort |
Babich, I.L. |
| title |
Plasma of electric arc discharge between copper electrodes in a gas flow |
| title_short |
Plasma of electric arc discharge between copper electrodes in a gas flow |
| title_full |
Plasma of electric arc discharge between copper electrodes in a gas flow |
| title_fullStr |
Plasma of electric arc discharge between copper electrodes in a gas flow |
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Plasma of electric arc discharge between copper electrodes in a gas flow |
| title_sort |
plasma of electric arc discharge between copper electrodes in a gas flow |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2008 |
| topic_facet |
Low temperature plasma and plasma technologies |
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http://dspace.nbuv.gov.ua/handle/123456789/110978 |
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Plasma of electric arc discharge between copper electrodes in a gas flow / I.L. Babich, V.F. Boretskij, A.N. Veklich // Вопросы атомной науки и техники. — 2008. — № 6. — С. 171-173. — Бібліогр.: 4 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
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| first_indexed |
2025-07-08T01:27:25Z |
| last_indexed |
2025-07-08T01:27:25Z |
| _version_ |
1837040191434391552 |
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PLASMA OF ELECTRIC ARC DISCHARGE
BETWEEN COPPER ELECTRODES IN A GAS FLOW
I.L. Babich, V.F. Boretskij, A.N. Veklich
Taras Schevchenko National University of Kyiv, Radio Physics Faculty,
64, Volodymyrs'ka Str., 01033 Kiev, Ukraine, e-mail: boretskij@univ.kiev.ua
Spectroscopy investigations of the thermal multicomponent plasma of the electric arc discharge between copper
electrodes in carbon dioxide and argon flows were carried out. The technique of calculation of plasma equilibrium com-
position is discussed. The influence of hydrodynamic cooling of gas flow on the plasma state is estimated. It was
assumed that the thermal dissociation of molecules of working gas play the key role in deviation from local
thermodynamic equilibrium (LTE) in plasma.
PACS: 51.30.+i, 52.70.-m
1. INTRODUCTION
As well known, a gas shielded arc is often used in
electric arc technology. A welding or arc cutting
processes is usually realized in argon, carbon dioxide,
nitrogen, oxygen and air or mixtures of different gases.
From one hand the spatial distribution of plasma
parameters are depended from flow rate or kind of
surround gas. And from another hand the metal vapour
content in arc discharge significantly determine these
parameters too. Therefore the investigations of electric
arc plasma with metal vapour in different shielding gases
are interesting from the viewpoint of industrial
applications and studying of basic physical phenomena as
well.
2. CALCULATION OF PLASMA
EQUILIBRIUM COMPOSITION
It is possible to calculate plasma composition in the
assumption of LTE using temperature and electron
density as known parameters.
The simplest situation is when we have electric arc
discharge in monoatomic gas such as argon. The
calculation of the plasma composition in this case can be
carried out by solution of the equations of perfect gas,
charge neutrality and Saha at a given pressure. For arc
discharge between copper electrodes we have to add one
more Saha equation due to the presence of copper vapour
in the discharge volume and equation of charge neutrality
must be improved for copper ion density.
When we consider electric arc discharge in molecular
gases or its mixtures, the influence of processes of
chemical reactions must be included in the calculation of
the plasma composition. The next problem is in
determination of the most important chemical reactions.
For example, carbon dioxide can be chosen as plasma
working gas. More than ten reactions occur for this
molecule and its secondary particles.
In our previous investigation [1] we considered that
with increasing temperature molecules of carbon dioxide
dissociate in such way:
CO2 ⇔ C + 2O . (1)
As dissociation energies of molecules O2 (5.1 eV) and C2
(6.2 eV) are rather low it was assumed that only atoms and
ions of oxygen and carbon would be present in plasma. The
ionization potential of molecules CO2 is rather high
(13.79 eV) and the amount of such molecules is insignificant
as the dissociation degree of carbon dioxide at temperature
value 6000 K equals 0.986 [1]. Consequently, the amount of
ions CO2
+ would be negligible. It was considered that there
are following particles in plasma: Cu, Cu+, C, C+, O, O+, CO2
and electrons.
In this paper to describe chemical reactions in carbon
dioxide we took into account next reactions:
CO2 ⇔ CO + ½O2 (2)
CO ⇔ C + O . (2)
O2 ⇔ 2O (2)
Therefore the calculation of the plasma composition was
carried out by solution of the equations of perfect gas (3),
charge neutrality (4), Saha (5), Guldberg-Waage (6) and
global chemical equilibrium (7) at an atmospheric pressure
using temperature and electron density obtained from
experimental investigation. The ionization potentials of
molecules CO and O2 are 14.01 eV and 12.08 eV
respectively, therefore their presence can be neglected. In
such improved calculation we considered that plasma consist
from Cu, Cu+, C, C+, O, O+, CO, O2, CO2 and electrons.
allbTNkp = , (3)
∑ += ie NN , (4)
O C, Cu, ,),( ⇒=
+
i
N
NN
NTS
i
ie
ei , (5)
22
/)( 2/1
COOCOCO NNNTD = ,
COOCCO NNNTD /)( = , (6)
22
/)( 2
OOO NNTD = ,
++ ++=++ CCCOOOO NNNNNN 222
2
. (7)
Such approach shows very good agreement with other
authors [2] in the range 3000 K < T < 15000 K.
2. EXPERIMENTAL INVESTIGATIONS
The arc was ignited between the end surfaces of the non-
cooled electrodes in a working gas flow of 6.45 slpm. The
diameter of the rod electrodes was of 6 mm. All experimental
investigations were carried out in average cross section of
discharge gap of 8 mm at arc currents 3.5 and 30 A.
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2008. № 6. 171
Series: Plasma Physics (14), p. 171-173.
mailto:boretskij@univ.kiev.ua
Because of the discharge spatial and temporal instabi-
lity the real-time recording of the spatial spectral line
emission was used. A CCD linear image sensor
accomplished fast scanning of spatial distributions of
radiation intensity [3].
To determine the radial profile of electron density we
investigated the shape of spectral line CuI 515.3 nm
broadened by the dominating quadratic Stark effect. The
measurements were carried out by techniques based on a
Fabri-Perot interferometer (FPI) [3].
Unfortunately the width of this spectral line at arc
current 3.5 A is practically comparable with instrument
function of FPI. Therefore, to extend the measuring range
of the electron density we studied the radial distribution
of absolute intensity of a spectral line CuI 465.1 nm [3].
The radial temperature profiles T(r) were determined
by Boltzmann plot method using CuI spectral lines 465.1,
510.5, 515.3, 521.8 and 578.2 nm. We used spectroscopic
data from [4].
3. RESULTS AND DISCUSSIONS
Radial profiles of plasma temperature T(r) and
electron density Ne(r) for different experimental modes
are shown in Figs. 1-4. These results were used in
calculation of plasma compositions (see Figs. 5, 6) by
improved set of equations Eq. 3-7.
0 1 2
4500
5000
5500
6000
T, K
r, mm
N
e
, m-3
Ne
T
1E20
1E21
Fig.1. Radial profiles of T and Ne for CO2 flow at 3.5 A
0 2 4
6000
7000
8000
9000
T, K
r, mm
Ne, m
-3
Ne
T
1E21
1E22
Fig.2. Radial profiles of T and Ne for CO2 flow at 30 A
According to previous calculations [1] the electric
discharge plasma in CO2 flow at arc currents 3.5 and 30 A
cannot be in LTE. In our case this conclusion confirmed
only at arc current 30A in axial region of discharge (see
Fig. 6). The difference at 3.5 A can be explained by
analysis of approaches for calculation equilibrium
composition. In contrast to [1] we add into consideration
CO and O2 in plasma. As one can see densities of these
particles are sufficiently high (see Fig. 5). Therefore, it is
necessary to take into consideration CO and O2 particles
for temperatures lower than 6000 K. In the range
6000 < T < 15000 K simplified technique [1] can be used.
0 1 2 3
4000
4800
5600
T, K
r, mm
Ne, m
-3
Ne
T
1E19
1E20
1E21
Fig.3. Radial profiles of T and Ne for Ar flow at 3.5 A
0 1 2 3 4 5
4000
6000
8000
T, K
r, mm
Ne, m
-3
NeT
1E21
1E22
Fig.4. Radial profiles of T and Ne for CO2 flow at 30 A
0 1 2
1E19
1E21
1E23
O
2
C
C+
O+
Cu+
Cu
CO
2
O
N
j
, m-3
r, mm
CO
e
Fig.5. Plasma composition for CO2 flow at 3.5 A
0 1 2 3 4 5
1E19
1E21
1E23
O2
C
C+
O+
Cu+
Cu
CO
2
O
Nj, m
-3
r, mm
CO
e
Fig.6. Plasma composition for CO2 flow at 30 A
172
0 1 2 3
1E16
1E18
1E20
1E22
1E24
Cu
Ar+
Cu+
Ar
N
j
, m-3
r, mm
e
Fig.7. Plasma composition for Ar flow at 3.5 A
0 1 2 3 4 5
1E16
1E18
1E20
1E22
1E24
Cu
Ar+
Cu+
Ar
Nj, m
-3
r, mm
e
Fig.8. Plasma composition for Ar flow at 30 A
In paper [1] the non-LTE state of CO2 plasma was
explained by the thermal dissociation of molecules of
working gas and hydrodynamic cooling of a gas flow. To
estimate the influence of such gas cooling we provide
similar investigations where argon as working gas was
used. It was found (see Figs. 7,8) that this effect have no
influence on the deviation from LTE in argon plasma.
Therefore, one can assume that hydrodynamic cooling
would not effect on the state of CO2 plasma at the same
conditions as well. By this assumption it is possible to
suppose that the thermal dissociation play the key role in
deviation from LTE in CO2 plasma at arc current 30 A.
CONCLUSIONS
The technique of calculation of the CO2 plasma
equilibrium composition was improved. It was shown that
in the range of temperatures lower than 6000 K it is
necessary to take into account CO and O2 particles.
It was shown that hydrodynamic cooling does not
effect on the deviation from LTE in monoatomic plasma
at the flow rate of 6.45 slpm. It is reason to state that this
effect has no influence on state of molecule gas plasma
too. Therefore, it was assumed that only the thermal
dissociation plays the key role in deviation from LTE in
CO2 plasma.
REFERENCES
1. A.N. Veklich, I.L. Babich, A.I. Cheredarchuk. Thermal
dissociation in thermal plasma of electric arc discharges
in air and carbon dioxide// Proc. of 15th Int. Symp. on
Plasma Chem. V.III., Orleans 9-13 July, 2001/ GREMI,
CNRS, Orleans, 2001, p. 849-853.
2. Y. Cressault, P. Teulet, J.J Gonzalez, A. Gleizes,
Ph. Robin-Jouan. Transport properties of CO2 arc plasma:
application for circuit-breaker modeling// Contributed
papers of XVIth Symp. on Phys. of Switch. Arc, Brno
5-9 Sept., 2005/ Univ. of Techn., Brno 2005, p. 46-49.
3. I.L. Babich, V.F. Boretskij and A.N. Veklich. Shapes
of spectral lines of nonuniform plasma of electric arc
discharge between copper electrodes// AIP Conference
Proc. 938. 2007, p. 252-257.
4. C.H. Corliss and W.R. Bozman. Experimental Transi-
tion Probabilities for Spectral Lines of Seventy Elements.
Moscow: “Mir”, 1968 (in Russian).
Article received 22.09.08.
ПЛАЗМА ЭЛЕКТРОДУГОВОГО РАЗРЯДА МЕЖДУ МЕДНЫМИ ЭЛЕКТРОДАМИ В ПОТОКЕ ГАЗА
И.Л. Бабич, В.Ф. Борецкий, А.Н. Веклич
Спектроскопическими методами исследована термическая многокомпонентная плазма электродугового
разряда между медными электродами в потоках аргона и углекислого газа. Обсуждается методика расчета
равновесного состава плазмы. Оценено влияние гидродинамического охлаждения потоком газа на состояние
плазмы. Предполагается, что термическая диссоциация молекул рабочего газа является основным механизмом
отклонения от локального термодинамического равновесия в плазме.
ПЛАЗМА ЕЛЕКТРОДУГОВОГО РОЗРЯДУ МІЖ МІДНИМИ ЕЛЕКТРОДАМИ У ПОТОЦІ ГАЗУ
І.Л. Бабіч, В.В. Борецький А.М. Веклич
Спектроскопічними методами досліджено термічну багатокомпонентну плазму електродугового розряду
між мідними електродами у потоках аргону та вуглекислого газу. Обговорюється методика розрахунку
рівноважного складу плазми. Оцінений вплив гідродинамічного охолодження потоком газу на стан плазми.
Припускається, що термічна дисоціація молекул робочого газу є основним механізмом відхилення від
локальної термодинамічної рівноваги в плазмі.
173
1. INTRODUCTION
2. calculation of plasma equilibrium composition
3. Results and Discussions
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