Final stage of cathode directed streamer propagation
The numerical simulations of the cathode directed streamer propagation in the atmospheric air at the constant voltage applied to the discharge gap are carried out. It is found an explanation of the streamer stopping possibility at the given distance from electrodes achieved in experiment. For the...
Gespeichert in:
| Datum: | 2016 |
|---|---|
| Hauptverfasser: | , , , , , , |
| Format: | Artikel |
| Sprache: | English |
| Veröffentlicht: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2016
|
| Schriftenreihe: | Вопросы атомной науки и техники |
| Schlagworte: | |
| Online Zugang: | http://dspace.nbuv.gov.ua/handle/123456789/115456 |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Zitieren: | Final stage of cathode directed streamer propagation / O. Bolotov, B. Kadolin, S. Mankovskyi, V. Ostroushko, I. Pashchenko, G. Taran, L. Zavada // Вопросы атомной науки и техники. — 2016. — № 6. — С. 252-254. — Бібліогр.: 5 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
irk-123456789-115456 |
|---|---|
| record_format |
dspace |
| spelling |
irk-123456789-1154562017-04-06T03:02:30Z Final stage of cathode directed streamer propagation Bolotov, O. Kadolin, B. Mankovskyi, S. Ostroushko, V. Pashchenko, I. Taran, G. Zavada, L. Low temperature plasma and plasma technologies The numerical simulations of the cathode directed streamer propagation in the atmospheric air at the constant voltage applied to the discharge gap are carried out. It is found an explanation of the streamer stopping possibility at the given distance from electrodes achieved in experiment. For the streamers, which cross the gap, it is obtained the transverse ionization wave propagation, which gives a contribution to the second maximum of the total current time dependence. Выполнено численное моделирование катодонаправленного стримера в атмосферном воздухе при постоянном напряжении, приложенном к разрядному промежутку. Найдено пояснение возможности останавливать стример на данном расстоянии от электродов, достигнутой в эксперименте. Для стримеров, которые пересекают промежуток, получено поперечное распространение волны ионизации, которое даёт вклад во второй максимум зависимости полного тока от времени. Виконане числове моделювання катодоспрямованого стримера в атмосферному повітрі при постійній напрузі, докладеній до розрядного проміжку. Знайдене пояснення можливості зупиняти стример на даній відстані від електродів, досягнутої у експерименті. Для стримерів, які перетинають проміжок, отримане поперечне поширення хвилі іонізації, яке дає внесок у другий максимум залежності повного струму від часу. 2016 Article Final stage of cathode directed streamer propagation / O. Bolotov, B. Kadolin, S. Mankovskyi, V. Ostroushko, I. Pashchenko, G. Taran, L. Zavada // Вопросы атомной науки и техники. — 2016. — № 6. — С. 252-254. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 52.80.Hc http://dspace.nbuv.gov.ua/handle/123456789/115456 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| topic |
Low temperature plasma and plasma technologies Low temperature plasma and plasma technologies |
| spellingShingle |
Low temperature plasma and plasma technologies Low temperature plasma and plasma technologies Bolotov, O. Kadolin, B. Mankovskyi, S. Ostroushko, V. Pashchenko, I. Taran, G. Zavada, L. Final stage of cathode directed streamer propagation Вопросы атомной науки и техники |
| description |
The numerical simulations of the cathode directed streamer propagation in the atmospheric air at the constant
voltage applied to the discharge gap are carried out. It is found an explanation of the streamer stopping possibility at
the given distance from electrodes achieved in experiment. For the streamers, which cross the gap, it is obtained the
transverse ionization wave propagation, which gives a contribution to the second maximum of the total current time
dependence. |
| format |
Article |
| author |
Bolotov, O. Kadolin, B. Mankovskyi, S. Ostroushko, V. Pashchenko, I. Taran, G. Zavada, L. |
| author_facet |
Bolotov, O. Kadolin, B. Mankovskyi, S. Ostroushko, V. Pashchenko, I. Taran, G. Zavada, L. |
| author_sort |
Bolotov, O. |
| title |
Final stage of cathode directed streamer propagation |
| title_short |
Final stage of cathode directed streamer propagation |
| title_full |
Final stage of cathode directed streamer propagation |
| title_fullStr |
Final stage of cathode directed streamer propagation |
| title_full_unstemmed |
Final stage of cathode directed streamer propagation |
| title_sort |
final stage of cathode directed streamer propagation |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2016 |
| topic_facet |
Low temperature plasma and plasma technologies |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/115456 |
| citation_txt |
Final stage of cathode directed streamer propagation / O. Bolotov, B. Kadolin, S. Mankovskyi, V. Ostroushko, I. Pashchenko, G. Taran, L. Zavada // Вопросы атомной науки и техники. — 2016. — № 6. — С. 252-254. — Бібліогр.: 5 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT bolotovo finalstageofcathodedirectedstreamerpropagation AT kadolinb finalstageofcathodedirectedstreamerpropagation AT mankovskyis finalstageofcathodedirectedstreamerpropagation AT ostroushkov finalstageofcathodedirectedstreamerpropagation AT pashchenkoi finalstageofcathodedirectedstreamerpropagation AT tarang finalstageofcathodedirectedstreamerpropagation AT zavadal finalstageofcathodedirectedstreamerpropagation |
| first_indexed |
2025-07-08T08:48:33Z |
| last_indexed |
2025-07-08T08:48:33Z |
| _version_ |
1837067942166003712 |
| fulltext |
ISSN 1562-6016. ВАНТ. 2016. №6(106)
252 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2016, № 6. Series: Plasma Physics (22), p. 252-254.
FINAL STAGE OF CATHODE DIRECTED STREAMER PROPAGATION
O. Bolotov, B. Kadolin, S. Mankovskyi, V. Ostroushko, I. Pashchenko, G. Taran, L. Zavada
NSC “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
E-mail: ostroushko-v@kipt.kharkov.ua
The numerical simulations of the cathode directed streamer propagation in the atmospheric air at the constant
voltage applied to the discharge gap are carried out. It is found an explanation of the streamer stopping possibility at
the given distance from electrodes achieved in experiment. For the streamers, which cross the gap, it is obtained the
transverse ionization wave propagation, which gives a contribution to the second maximum of the total current time
dependence.
PACS: 52.80.Hc
INTRODUCTION
At the constant applied voltage, the positive corona
in atmospheric air usually operates in pulse mode,
through the cathode directed streamers. Experiments
show that in positive corona the energy expense on one
ozone molecule forming is less than in negative corona.
Positive streamer propagation is widely studied [1] and
its study is continued [2, 3]. In the present work, a final
stage of streamer propagation is studied.
Dependently on the discharge parameters, the
streamer can either cross the gap between electrodes or
stop somewhere in the gap. Experiments show that in
the first case there are two peaks in the total current
time dependence, whereas in the second case there is
one peak.
The streamer stopping in the gap far from electrodes
itself at first sight seems surprising phenomenon.
Indeed, if an ionization zone ahead of streamer has
moved sufficiently far from the needle anode after the
beginning of streamer propagation, but it has not come
to a very short distance on the plane cathode, then some
further streamer propagation does not change
considerably the electric field in the ionization zone.
And it may be supposed that all streamers, which have
passed the considerable part of the gap, will come to
cathode. But in the experiments, the ability is
demonstrated to stop the streamer in any position, not
very near to electrodes.
To find out the causes of phenomena observed when
a streamer stops in the gap or comes to cathode, the
numerical simulations were carried out. In the
calculations, there were taken into account drift and
diffusion of electrons and ions, positive and negative,
and the reactions of ionization, recombination, ion-ion
and electron-ion, and attachment. The equations and
some details of calculations are given in [4]. For the
source of electrons necessary to begin the avalanches, it
was taken electron emission from cathode under
different assumption about photon distribution. Namely,
it was uniform over cathode, or it was formed by flow
without absorption parallel to the axial symmetry axis,
or by spherically symmetric flow with absorption.
1. STREAMER STOPPING IN THE GAP
As one of the causes of the streamer stopping in the
discharge gap with a needle anode (together with the
field non-uniformity), it is sometimes proposed the
streamer channel conductivity decrease through electron
attachment. But in [5], there is detailed substantiation of
formal possibility of the stationary streamer propagation
in the unbounded space with an attaching gas and
uniform external field. The characteristic length of the
well conducting part of such streamer is determined
with the product of the streamer velocity and the
characteristic time of a free electron motion before the
attachment. Farther from the streamer head, the
streamer channel is filled with the positive and negative
ions, which density decrease with time through
recombination. But all streamer characteristics in the
frame of reference moving together with such streamer
and the streamer propagation velocity are constant. In
the real bounded discharge gap with non-uniform field,
the intensive attachment to a certain extent may to
promote the streamer stopping through the conductivity
decrease in the space near the needle anode. The field
strengthening here (caused by the decrease of the
medium conductivity and the ability to screen the field)
leads to the potential drop increase on the streamer
channel and to its decrease on the rest part of the gap,
and so, to the field weakening in the ionization zone.
But if such potential redistribution takes place at the
stage of the streamer propagation when the distances
from the ionization zone to anode and cathode are the
values of the same order then the tendencies, in the
ionization zone, to the field weakening (due to the
conductivity decrease) and strengthening (due to the
streamer movement to cathode) are the factors of the
same order, and so, the streamer channel conductivity
decrease caused by electron attachment hardly may be
decisive circumstance for the streamer stopping far from
electrodes.
One of the possible causes of such stopping is
suggested by the following experimental fact: it is
comparatively easy to stop the streamer in the given
point of the gap by the decrease of the applied voltage
from the values, at which the pulsed mode of discharge
with the streamers crossing all gap had been already
stated, whereas the increase of voltage from the small
values at once gives the streamers, which cross the
whole gap. So, it is natural to pay attention to the
different conditions of the propagation of the first and
next streamers.
Before the first streamer start the distribution of free
electrons and negative ions in the discharge gap is
determined by external sources. If the sources are
uniform then in the gas with low intensity of attachment
the distribution of free electrons is near to linear one and
ISSN 1562-6016. ВАНТ. 2016. №6(106) 253
the value of electron density near cathode is very small
(in connection with electron drift), whereas in the gas
with high intensity of attachment the similar distribution
is characteristic for the negative ions.
The next streamers are propagating in the gas with
the particles, formed by the previous streamers. There
are exited particles and negative ions, which may be
ionized due to interaction with other exited particles or
by photons or electrons having comparatively small
energy. In the time intervals between streamers, the drift
and recombination make the negative ion distribution in
the gap non-homogeneous along the field direction.
Nearer to anode the negative ion density is greater, and
here, the more favorable conditions for the streamer
propagation are formed. At such distance from anode,
where the negative ion density is too small, so that
relevant source of free electrons is too week, the
streamer stops. The dependence of the quasi-stationary
streamer propagation velocity on the average field
strength for the different background electron density is
shown in the Fig. 1. Streamers cannot propagate with
too small velocity.
35 40 45 50
0
1
2
3
4
v
e
lo
c
it
y
,
1
0
7
c
m
/s
average strength, kV/cm
Fig. 1. Quasi-stationary streamer propagation velocity
for the different background electron density
(10
…10
cm
, from right to left)
For the streamer, propagating in the bounded gap,
the electric field strength in ionization zone has a
tendency to increase, as the charge of the streamer head
is gathered with aid of charge displacement on the
increased streamer length. But the transverse streamer
dimension is not fixed. The approximately determined
quantity is the electric field strength value in ionization
zone. It is determined with the characteristic type of the
dependence of the ionization coefficient on the field
strength. Namely, the strength in ionization zone
approximately corresponds to such values, the decrease
from which leads to considerable decrease of ionization
coefficient, whereas increase from which leads to only
small ionization coefficient increase. And the value of
transverse streamer dimension, for the given potential of
the streamer head with respect to cathode, should give
the required field strength value in ionization zone. As a
result, with the increase of the streamer length at the
beginning of its propagation, the transverse streamer
dimension increases, with approximately constant
values of the field strength and the densities of electron
current, leading to the increase both the displacement
current and the conductance current. The streamer
stopping gives the decrease of the total current for a few
orders. The total current time dependence for the
streamers stopping in the discharge gap far from
electrodes has one maximum.
2. STREAMER STOPPING NEAR CATHODE
If the voltage applied to the gap is sufficiently large
then the pulsed mode of positive corona takes a form of
streamers, which cross the whole gap. The streamer
approach to cathode is accompanied with increase of the
field strength in ionization zone and with intensification
of impact ionization and radiation of photons able to
cause ionization in gas or electron emission from
cathode. The conductivity and displacement currents
considerably increase. But subsequent movement of the
streamer head to cathode leads to decrease of dimension
of ionization zone. Though this decrease is accompanied
with the field strengthening, the local intensity of
photon radiation and electron multiplication almost does
not enhance, as relevant coefficients for radiation and
ionization are almost independent on the field strength
at such strength level. So, the total rate of ionization
decreases, leading to the conductivity current decrease.
Also, due to ionization and the charged particle drift, in
the space very near to cathode, the density of positive
ions non-compensated by electrons is increased,
enhancing the tendency to the potential redistribution,
accompanied with some decrease of the rate of near-
cathode field strengthening, and so, with the
displacement current decrease.
The described processes give maximum in the total
current time dependence. But after the total current
decrease, its new increase takes place. It is connected
with the going out of large amount of positive ions to
cathode and with transverse ionization wave
propagation over the cathode surface. Usually, the
number of electrons knocked out from cathode by
photons generated in gap by one electron is much less
than the number of ionization acts made by the same
electron. Also, the ion-electron emission coefficient is
usually small. As a result, the total positive charge
going out to cathode is only slightly less than the total
negative charge going out to anode. Positive ion
distribution formed by avalanches near cathode is
characterized by so small distance of density doubling,
that the ion going out may give nanosecond time of the
total current doubling.
Fig. 2. Electron density distribution in the near-cathode
space at the time near maximum of total current for the
different variants of photoemission (in the text)
Further positive ion density increase in the space
very near to cathode leads to further potential
redistribution with the field strengthening in the
254 ISSN 1562-6016. ВАНТ. 2016. №6(106)
streamer channel, field weakening near cathode, and
with end of the transverse ionization wave propagation
(as potential values in the different points of the near-
cathode space become approximately equal to one at
cathode). The electron density distribution in the near-
cathode space at the time near maximum of total current
is shown in the Fig. 2 for the cases of photoemission
based on the photons non-absorbing in gas with uniform
distribution over cathode (left) and on the photons with
absorption length 10 m (right); the right boundaries are
cathodes, the horizontal pictures dimensions are
0.5 mm, the color range (at the top, from white to black)
corresponds to (10
…10
) cm
(in logarithmic scale,
with taking the color for the nearest lesser value).
Having passed the second maximum, the total current
begins to decrease.
Positive ions go out comparatively quickly from the
space, where the field strength is large. In the case when
the ionization intensity is not sufficient to keep the
positive ion number in the gap, the boundary of quasi-
neutral plasma is moving from cathode. Electrons and
negative ions also go out from the gap, but the field near
anode remains sufficiently strong for intensive
ionization. An accidental ionization enhancement here
leads to weakening of the field and ionization intensity,
and this end of the streamer channel stays near anode.
Through recombination and attachment, the channel
conductivity decreases and the potential drop on the
channel increases. So, at this stage, the field near the
cathode end of the channel is weaker than one at the
stage of streamer propagation, and it is not sufficient to
renew the propagation. The channel destruction or the
considerable decrease of its conductivity gives the
possibility for the near-anode ionization to form the
space charge, sufficient for new streamer development.
In the other case (for the sufficiently large applied
voltage), when the ionization process is quasi-
stationary, the gas heating usually leads to the spark
formation.
CONCLUSIONS
In positive corona the cathode-directed streamers
may cross the discharge gap or stop in it. The possibility
of the streamer stopping at the given (not too small)
distance from cathode is connected with the presence of
negative ions and exited particles, which have remained
after the previous streamers and play a role of additional
source of electrons on the way of new streamer. The
streamer stopping here is connected with the
considerable decrease of negative ion density nearer to
cathode.
When the streamer crosses the whole gap, there are
two maximums of the total current. The first maximum
is connected with the stopping of ionization wave. The
second maximum is connected with the positive ion
going out of the gap and with the ionization wave over
the cathode surface. The characteristics of this wave are
dependent on the intensity of electron emission from
cathode. The time of its propagation is bounded with the
time of the considerable increase of the positive ion
density near cathode, which leads to essential potential
redistribution.
REFERENCES
1. Yu.P. Raizer. Gas discharge physics. Springer:
“Verlag”. 1991.
2. O.V. Bolotov, V.I. Golota, B.B. Kadolin, et al.
Similarity laws for cathode-directed streamers in gaps
with an inhomogeneous field at elevated air pressure //
Plasma Physics Reports. 2010, v. 36, № 11, p. 1000-
1011.
3. O.V. Manuilenko, V.I. Golota. Computer simulation
of positive streamer dynamics in strongly non-uniform
electric fields in air. Effect of applied voltage on a
streamer velocity for different needle radii // Problems
of Atomic Science and Technology. Series “Plasma
Physics” (20). 2014, № 6(94), p. 187-190.
4. O. Bolotov, B. Kadolin, S. Mankovskyi, et al. Quasi-
stationary streamer propagation // Problems of Atomic
Science and Technology. Series ”Plasma Electronics
and New Methods of Acceleration” (9). 2015, № 4,
p. 185-188.
5. M.I. Dyakonov, V.Yu. Kachorovsky. Stationary
propagation of streamers in electronegative gases // Sov.
Phys. JETP. 1990, v. 71, № 3, p. 498-505.
Article received 22.10.2016
КОНЕЧНАЯ СТАДИЯ РАСПРОСТРАНЕНИЯ КАТОДОНАПРАВЛЕННОГО СТРИМЕРА
О. Болотов, Б. Кадолин, С. Маньковский, В. Остроушко, И. Пащенко, Г. Таран, Л. Завада
Выполнено численное моделирование катодонаправленного стримера в атмосферном воздухе при
постоянном напряжении, приложенном к разрядному промежутку. Найдено пояснение возможности
останавливать стример на данном расстоянии от электродов, достигнутой в эксперименте. Для стримеров,
которые пересекают промежуток, получено поперечное распространение волны ионизации, которое даёт
вклад во второй максимум зависимости полного тока от времени.
КІНЦЕВА СТАДІЯ ПОШИРЕННЯ КАТОДОСПРЯМОВАНОГО СТРИМЕРА
О. Болотов, Б. Кадолін, С. Маньковський, В. Остроушко, І. Пащенко, Г. Таран, Л. Завада
Виконане числове моделювання катодоспрямованого стримера в атмосферному повітрі при постійній
напрузі, докладеній до розрядного проміжку. Знайдене пояснення можливості зупиняти стример на даній
відстані від електродів, досягнутої у експерименті. Для стримерів, які перетинають проміжок, отримане
поперечне поширення хвилі іонізації, яке дає внесок у другий максимум залежності повного струму від
часу.
|