The influence of cathode material on the characteristics of pulsed negative corona in oxygen
Change in time for the shape of the discharge current pulses of the pulsed negative corona in oxygen with copper and stainless steel cathodes has been studied for two discharge modes. The change lies in the decrease of the pulse amplitude and duration at half maximum. It is shown that for stainless...
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Golota, V.I. Kadolin, B.B. Taran, G.V. Pashchenko, I.A. 2023-12-06T10:08:21Z 2023-12-06T10:08:21Z 2021 The influence of cathode material on the characteristics of pulsed negative corona in oxygen / V.I. Golota, B.B. Kadolin, G.V. Taran, I.A. Pashchenko // Problems of Atomic Science and Technology. — 2021. — № 6. — С. 93-98. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS: 52.80.Hc DOI: https://doi.org/10.46813/2021-136-093 https://nasplib.isofts.kiev.ua/handle/123456789/195646 Change in time for the shape of the discharge current pulses of the pulsed negative corona in oxygen with copper and stainless steel cathodes has been studied for two discharge modes. The change lies in the decrease of the pulse amplitude and duration at half maximum. It is shown that for stainless steel cathodes, the amount of electric charge transferred in one pulse of the discharge current is 15% greater than for copper cathodes. It is also shown that under the maximum load mode, the amount of charge transferred in one pulse of the discharge current is decreased with time by 10% for both types of cathodes. It is shown that ozone synthesis in the electrode system with copper cathodes is 25% more efficient. Досліджено зміну в часі форми імпульсів розрядного струму імпульсної негативної корони в кисні з мідними катодами і катодами з нержавіючої сталі для двох режимів горіння розряду, що полягає в зменшенні амплітуди імпульсу і збільшенні їх тривалості на напіввисоті. Показано, що для катодів з нержавіючої сталі кількість електричного заряду, що переноситься в одному імпульсі розрядного струму, на 15% більше ніж для мідних катодів. Також показано, що в режимі максимального навантаження величина заряду, що переноситься в одному імпульсі розрядного струму з часом зменшується на 10% для обох типів катодів. Показано, що в електродній системі з катодами з міді напрацювання озону відбувається на 25% ефективніше. Исследовано изменение во времени формы импульсов разрядного тока импульсной отрицательной короны в кислороде с медными катодами и катодами из нержавеющей стали для двух режимов горения разряда, заключающееся в уменьшении амплитуды импульса и увеличении их длительности на полувысоте. Показано, что для катодов из нержавеющей стали количество электрического заряда, переносимого в одном импульсе разрядного тока, на 15% больше, чем для медных катодов. Также показано, что в режиме максимальной нагрузки величина заряда, переносимого в одном импульсе разрядного тока, со временем уменьшается на 10% для обоих типов катодов. Показано, что в электродной системе с катодами из меди наработка озона происходит на 25% более эффективно. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Novel and non-standard acceleration technologies The influence of cathode material on the characteristics of pulsed negative corona in oxygen Вплив матеріалу катода на характеристики імпульсної негативної корони в кисні Влияние материала катода на характеристики импульсной отрицательной короны в кислороде Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
The influence of cathode material on the characteristics of pulsed negative corona in oxygen |
| spellingShingle |
The influence of cathode material on the characteristics of pulsed negative corona in oxygen Golota, V.I. Kadolin, B.B. Taran, G.V. Pashchenko, I.A. Novel and non-standard acceleration technologies |
| title_short |
The influence of cathode material on the characteristics of pulsed negative corona in oxygen |
| title_full |
The influence of cathode material on the characteristics of pulsed negative corona in oxygen |
| title_fullStr |
The influence of cathode material on the characteristics of pulsed negative corona in oxygen |
| title_full_unstemmed |
The influence of cathode material on the characteristics of pulsed negative corona in oxygen |
| title_sort |
influence of cathode material on the characteristics of pulsed negative corona in oxygen |
| author |
Golota, V.I. Kadolin, B.B. Taran, G.V. Pashchenko, I.A. |
| author_facet |
Golota, V.I. Kadolin, B.B. Taran, G.V. Pashchenko, I.A. |
| topic |
Novel and non-standard acceleration technologies |
| topic_facet |
Novel and non-standard acceleration technologies |
| publishDate |
2021 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Вплив матеріалу катода на характеристики імпульсної негативної корони в кисні Влияние материала катода на характеристики импульсной отрицательной короны в кислороде |
| description |
Change in time for the shape of the discharge current pulses of the pulsed negative corona in oxygen with copper and stainless steel cathodes has been studied for two discharge modes. The change lies in the decrease of the pulse amplitude and duration at half maximum. It is shown that for stainless steel cathodes, the amount of electric charge transferred in one pulse of the discharge current is 15% greater than for copper cathodes. It is also shown that under the maximum load mode, the amount of charge transferred in one pulse of the discharge current is decreased with time by 10% for both types of cathodes. It is shown that ozone synthesis in the electrode system with copper cathodes is 25% more efficient.
Досліджено зміну в часі форми імпульсів розрядного струму імпульсної негативної корони в кисні з мідними катодами і катодами з нержавіючої сталі для двох режимів горіння розряду, що полягає в зменшенні амплітуди імпульсу і збільшенні їх тривалості на напіввисоті. Показано, що для катодів з нержавіючої сталі кількість електричного заряду, що переноситься в одному імпульсі розрядного струму, на 15% більше ніж для мідних катодів. Також показано, що в режимі максимального навантаження величина заряду, що переноситься в одному імпульсі розрядного струму з часом зменшується на 10% для обох типів катодів. Показано, що в електродній системі з катодами з міді напрацювання озону відбувається на 25% ефективніше.
Исследовано изменение во времени формы импульсов разрядного тока импульсной отрицательной короны в кислороде с медными катодами и катодами из нержавеющей стали для двух режимов горения разряда, заключающееся в уменьшении амплитуды импульса и увеличении их длительности на полувысоте. Показано, что для катодов из нержавеющей стали количество электрического заряда, переносимого в одном импульсе разрядного тока, на 15% больше, чем для медных катодов. Также показано, что в режиме максимальной нагрузки величина заряда, переносимого в одном импульсе разрядного тока, со временем уменьшается на 10% для обоих типов катодов. Показано, что в электродной системе с катодами из меди наработка озона происходит на 25% более эффективно.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/195646 |
| citation_txt |
The influence of cathode material on the characteristics of pulsed negative corona in oxygen / V.I. Golota, B.B. Kadolin, G.V. Taran, I.A. Pashchenko // Problems of Atomic Science and Technology. — 2021. — № 6. — С. 93-98. — Бібліогр.: 4 назв. — англ. |
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ISSN 1562-6016. ВАНТ. 2021. № 6(136) 93
https://doi.org/10.46813/2021-136-093
THE INFLUENCE OF CATHODE MATERIAL ON THE
CHARACTERISTICS OF PULSED NEGATIVE CORONA IN OXYGEN
V.I. Golota, B.B. Kadolin, G.V. Taran, I.A. Pashchenko
National Science Center “Kharkov Institute of Physics and Technology”, Kharkiv, Ukraine
E-mail: kodolin@kipt.kharkov.ua
Change in time for the shape of the discharge current pulses of the pulsed negative corona in oxygen with copper
and stainless steel cathodes has been studied for two discharge modes. The change lies in the decrease of the pulse
amplitude and duration at half maximum. It is shown that for stainless steel cathodes, the amount of electric charge
transferred in one pulse of the discharge current is 15% greater than for copper cathodes. It is also shown that under
the maximum load mode, the amount of charge transferred in one pulse of the discharge current is decreased with
time by 10% for both types of cathodes. It is shown that ozone synthesis in the electrode system with copper cath-
odes is 25% more efficient.
PACS: 52.80.Hc
INTRODUCTION
Barrierless gas discharges of atmospheric pressure in
oxygen-containing gases with highly inhomogeneous
distribution of electric field are effective ozone sources.
The issue of increasing the energy efficiency of ozone
synthesis in this type of gas discharge is urgent, espe-
cially ozone production with high concentration. Ozone
generators on its basis are widely used for tire recycling
[1, 2], wastewater treatment [3], etc. Research on this
type of gas discharge is aimed at determining the condi-
tions under which it is possible to increase the energy
put by the discharge per unit volume of gas while main-
taining the volumetric discharge, and increasing the
efficiency of ozone synthesis. This issue is solved by
selecting the parameters of the discharge gap geometry,
parameters of the electric pulsed power supply and gas-
dynamic conditions. Among the gas-dynamic condi-
tions, only the temperature, pressure and rate of gas
pumping along the discharge gap are the tools which
can have the influence on the discharge characteristics.
However, they provide little information on the gas-
dynamic conditions directly in the ionization region of
the discharge, which is key both for the discharge and
plasma-chemical reactions.
In [4], experimentally, on the basis of the analysis on
the radiation spectrum of the discharge active zone, the
gas temperature at the corona-forming tip was deter-
mined, which was ~ 600 K. Due to this temperature
value, ozone destruction process is enhanced and ozone
cannot be obtained with high efficiency. Therefore, in
this paper, an attempt has been made to study the possi-
bility of controlling the thermodynamic conditions in
the immediate vicinity of the corona-forming electrode
surface by enhancing the heat removal through the co-
rona-forming cathode surface. For this, the cathodes
made of the material with high thermal conductivity
(copper) were used. Traditionally, the stainless steel
cathodes were used in ozone generators due to their high
corrosion resistance. However, stainless steel (s/s) has a
thermal conductivity coefficient of ~ 20 W/(m°С), which
can lead to excessive heating of the cathode surface.
The equilibrium temperature of the cathode surface
corresponds to the conditions under which the heat flux
from the discharge to the cathode surface is equal to the
heat flux along the cathode. If the cathodes made of the
material with high thermal conductivity are used, the
cathode surface temperature can be significantly re-
duced. This will change the discharge mode. Also, both
the electrodynamic parameters of the negative pulsed
corona and the rate of plasma chemical synthesis will be
affected.
To achieve the goal of the work, a multicathode
electrode system with high-voltage pulsed power supply
was chosen. The discharge was ignited in a working gas
with the increased oxygen concentration up to ~ 94%.
The cathodes for the electrode system were made of
copper (thermal conductivity coefficient of
390 W/m/°C) and stainless steel 12X18H10T (S32109)
(thermal conductivity coefficient of 15 W/m/°C). Thus,
comparing the discharge characteristics of these two
electrode systems, it will be possible to draw a conclu-
sion on the significance of heat removal from the dis-
charge active zone and the efficiency of ozone synthe-
sis.
EXPERIMENTAL STAND
The experimental stand (Fig. 2) includes the unit of
plasma-chemical reactors (PCRs), oxygen source,
pulsed power supply unit and measuring unit.
The experiments were carried out on the unit con-
sisting of two separate PCRs connected in series along
the working gas flow. The plasma-chemical reactor is a
hollow cylinder made of finely dispersed graphite
500 mm long and 38 mm in inner diameter, which
serves as an anode. The cathode is coaxially located
inside the cylinder, which is a rod with the diameter of
8 mm, on which 60 flat star-like cathode sections
(Fig. 1) are fixed. The distance between the cathode
sections is 6 mm. Each cathode section has 15 separate
cathodes, each 5 mm long and 0.5 mm wide.
The distance from the cathode section center to the
cathode end surface was 14.5 mm. The discharge gap
was 4.5 mm, respectively. The deviation of the dis-
charge gap value from the specified one is less than
20 µm for each cathode. The PCR electrical capacitance
was 57 pF for the PCR with a copper cathode and 54 pF
for the PCR with a stainless steel cathode.
ISSN 1562-6016. ВАНТ. 2021. № 6(136) 94
Fig. 1. Cathode section
The oxygen source includes an oxygen concentrator
AirSep-D with the productivity of 1.2 m
3
/h for a gas
mixture that contains 92...95% of oxygen, up to 8% of
nitrogen, water vapor and argon. The water vapor con-
tent corresponds to a dew point of -90C. For the nor-
mal operation of the oxygen concentrator, two oil-free
air compressors AtlasCopco LF7 FF and AtlasCopco
LF7 with the productivity of 0.66 m
3
/min each and
working pressure of up to 120 psig were used. The
AtlasCopco LF7 FF air compressor is additionally
equipped with a refrigerated air dryer with a dew point
of + 3C. Gas from the oxygen concentrator is accumu-
lated in two receivers with the capacity of 300 liters
each, which are connected in series. To control the oxy-
gen consumption, a rotameter RM 0.12 G with the
measurement range from 0.001 m
3
/h to 0.12 m
3
/h was
used. The oxygen concentrtion in thegas mixture was
measured with an M&C O2-Analyzer PMA-10 para-
magnetic oxygen analyzer. Oozone concentratiion in the
gas mixture was measured using a Teledyne Instruments
Ozone Monitor 465 H. An ozone destructor was in-
stalled at the outlet of the gas path.
Fig. 2. Block diagram of the experimental stand
The electrical part of the experimental stand includes
an HV pulsed power supply, PCR unit and measuring
instruments. The HV pulsed power supply can operate
under the combined power supply mode: high-voltage
pulses against bias voltage. The value for the back-
ground level of the bias voltage is set by the ratio of
intrinsic electric capacity for the PCR C4 unit in Fig. 4,
and the capacitance of the capacitors for the bias voltage
circuit C2 in Fig. 4. The maximum level of bias voltage
is up to 3 kV. The HV pulsed power supply is designed
on the basis of HV pulse transformer and has the fol-
lowing parameters: the pulse shape is sinusoidal, pulse
repetition rate is from 200 Hz to 20 kHz, amplitude of
HV pulses is from 7 to 12 kV, pulse width at half-height
is 1 µs. It is possible to smoothly adjust the amplitude of
HV pulse and repetition rate.
Fig. 3. Oscillogram of HV pulses
The HV pulsed power supply (Fig. 3) parameters for
the PCR unit were measured using a Tektronix P6015A
capacitive HV probe, which has the division ratio of
1:1000, resistance of 100 MΩ, electric capacitance of
3 pF, 20 kV DC, 40 kV pk 100 ms, bandwidth of
90 MHz. The HV probe is connected to a Tektronix
TDS 2024B four-channel oscilloscope with the band-
width of 200 MHz. The electric current of the PCR unit
was measured using a Tektronix CT-1 current probe
with the transformation ratio of 5 mV/1 mA and band-
width of 1 GHz.
Fig. 4. Schematic diagram of the experimental stand.
C1 is the charging capacitor, C2 is the bias voltage
capacitor, C3 is the capacitor that simulates the electric
capacity of the PCR unit, C4 is the intrinsic capacitance
of the PCR unit
A compensating circuit is used to measure the dis-
charge current. Since the electric power supply is of
pulsed nature, the current flowing through the circuit of
the PCR unit is the sum of gas discharge current and
charging current of the PCR intrinsic capacitance, the
so-called capacitive current, which has nothing to do
with the gas discharge current. To separate the gas-
discharge current from the total current, an additional
electrical circuit was used, which includes a high-
voltage capacitor connected to the electrical power
circuit in parallel to the PCR unit. The value for the
electric capacitance of the capacitor must be exactly
equal to the electric capacitance of the PCR unit.
Oscillographic recording of the current flowing through
the discharge gap and the current flowing in the circuit
of this capacitor is carried out simultaneously. In order
to separate exactly the discharge current, it is necessary
to subtract the current flowing in the capacitor circuit
from the total current flowing through the PCR unit.
The current is measured using a Tektronix CT 1 current
ISSN 1562-6016. ВАНТ. 2021. № 6(136) 95
probe, which is a measuring transformer. The primary
winding of this transformer is a conductor through
which electric current flows. Therefore, in case when
the conductor, through which the total current of the
PCR unit flows, and the conductor with the secondary
capacitor current play the role of primary windings,
which are switched in the opposite way, the subtraction
of the secondary capacitor current from the total current
of the PCR unit is carried out in a circuit, directly in the
measurement process. The obtained result is a gas dis-
charge current. In Fig. 5, an example for one of the
obtained oscillograms is presented. The shape of the HV
voltage pulse is shown with the upper black curve. The
shape of the discharge current pulse is shown with the
lower red curve.
Fig. 5. Example of the oscillogram for HV pulse
and discharge current
EXPERIMENTAL RESULTS
In the course of the experiments, the temporal dynam-
ics of both the concentration of ozone produced by the
PCR unit and the change in the shape of the discharge
current pulses for the PCR were studied with the fixed
parameters of the HV pulsed power supply for two elec-
trode systems: with copper and stainless steel cathodes.
All the studies were carried out at the HV pulse repe-
tition rate of 15 kHz and fixed value of the bias power
supply voltage. The PCR operating mode with a partial
load, HV pulse energy of about 7.5 mJ with a maximum
load and pulse energy of 9.5 mJ were studied. The maxi-
mum load corresponds to the operating mode of the PCR
unit, when the transition of the pulsed corona to the spark
discharge is completely excluded. The intrinsic electric
capacitance of the PCR unit with copper cathodes was
114.5 pF, with stainless steel cathodes – 107 pF. The oxy-
gen consumption was 60 L/min, oxygen purity was 94%.
In Figs. 6-9, the oscillograms of the discharge cur-
rent pulses for the PCR unit with stainless steel and
copper cathodes are shown depending on the duration of
operation. Oscillograms are synchronized with a high-
voltage pulse. In all the figures, it is shown that the
shape of current pulses is changed over time. The cur-
rent pulse itself is shifted to the right in time with re-
spect to HV pulse. At the partial load, for both stainless
steel and copper cathodes, the current pulse becomes
longer at half height. The amplitude of the current pulse
for copper cathodes is not changed, and for stainless
steel cathodes, it is slightly decreased. At the maximum
load, the amplitude of the current pulse is decreased,
and the pulse width at half height is increased. In gen-
eral, the nature of changes in the shape of current pulses
at the partial and maximum loads are identical, but at
the maximum load, they are much stronger. It is sug-
gested that these changes are caused by cathode heating.
Fig. 6. Oscillograms of discharge current pulses, PCR
with stainless steel cathodes at the partial load and HV
pulse energy of 7.55 mJ recorded at different duration
of operation
PCR is a multi-cathode electrode system, and the
PCR current pulse is the sum of current pulses for each
individual cathode. Since the gas temperature is in-
creased as it passes along the electrode system, the tem-
perature of the cathodes located closer to the gas inlet of
the PCR unit is lower than of those located closer to the
outlet. Therefore, the discharge at the cathodes located
at different distances from the gas inlet of the PCR unit
occurs at different times as the voltage is increased at
the leading edge of the voltage pulse. This explains the
increase in the current pulse duration and, in part, the
decrease in its amplitude.
In more heated gas, the current pulse amplitude of
the individual cathode is greater at the same voltage.
This compensates the decrease in the amplitude for the
total current pulse of the PCR unit due to its expansion.
For copper cathodes at the partial load, the amplitude of
the current pulse did not change at all. To estimate the
value of the total pulse current, on the basis of the ob-
tained oscillograms, the charge transferred in one cur-
rent pulse of the PCR unit was calculated.
Fig. 7. Oscillograms of the discharge current pulses,
PCR with stainless steel cathodes at the maximum load
and HV pulse energy of 9.657 mJ recorded
at different operation duration
ISSN 1562-6016. ВАНТ. 2021. № 6(136) 96
Fig. 8. Oscillograms of the discharge current pulses,
PCR with copper cathodes at the partial load
and HV pulse energy of 7.775 mJ recorded
at different operation duration
Fig. 9. Oscillograms of the discharge current pulses,
PCR with copper cathodes at the maximum load
and HV pulse energy of 9.482 mJ recorded
at different operation duration
Fig. 10. Charge transferred in the discharge current
pulse of the PCR with stainless steel and copper
cathodes at the maximum and partial power depending
on the duration of operation
In Fig. 10, the dependence of the charge value trans-
ferred in the discharge current pulse for the PCR with
stainless steel and copper cathodes at the partial and
maximum loads is shown. At the partial load, in the first
minutes of PCR operation, there is a tendency to in-
crease the charge in the current pulse. After a certain
time, the amount of charge transferred in the current
pulse is stabilized. At the maximum load, both for stain-
less steel and copper cathodes, the increase in the pulse
charge is replaced by its decrease. For copper cathodes,
there is a long period of ~ 26 min, when the value of the
transferred charge remains unchanged.
In Fig. 10, it is shown that the amount of charge
transferred in the discharge current pulse for stainless
steel cathodes is greater than for copper cathodes under
all the modes of PCR operation. Under the partial load
mode, this difference reaches 20%, under the maximum
load mode, the difference is noticeably lower than ~ 5%.
This can serve as a confirmation that the temperature of
corona surface for stainless steel cathodes is higher than
that of copper cathodes.
Fig. 11. The concentration of ozone generated
by the PCR unit with stainless steel and copper
cathodes depending on the duration of operation
In Fig. 11, the dependence of ozone concentration at
the outlet of the PCR unit on the duration of the PCR
unit operation is shown. Comparing these curves with
the curves shown in Fig. 10, it can be seen that the
course of the curve showing the concentration depend-
ence on the operating time practically repeats the corre-
sponding dependence of the charge transferred in the
current pulse, both for the PCR with stainless steel and
copper cathodes.
The data presented in Fig. 11 show that ozone con-
centration generated by the PCR unit with copper cath-
odes is 25% higher than ozone concentration generated
by the PCR with stainless steel cathodes under the par-
tial and maximum loads. The energy efficiency of ozone
synthesis for the PCR with stainless steel cathodes is
16.92 Wand 14.7 Wh/gO3 for the maximum and partial
load modes, respectively. The energy efficiency of
ozone synthesis for the PCR with copper cathodes is
13.62 and 8.925 Wh/gO3 for the maximum and partial
loads, respectively.
DISCUSSION OF EXPERIMENTAL
RESULTS
The results obtained show significant differences in
the characteristics of PCR operation with stainless steel
and copper cathodes. Ozone production by the PCR unit
with copper cathodes is about 20% higher both at the
partial and maximum loads. At the maximum load for
stainless steel cathodes, ozone concentration is de-
creased over time. Energy efficiency for both modes is
ISSN 1562-6016. ВАНТ. 2021. № 6(136) 97
approximately the same. This may show a significantly
higher gas temperature for the corona surfaces of stain-
less steel cathodes. For the PCR with copper cathodes,
the energy efficiency of ozone synthesis differs by 50%
depending on the load mode, and at the maximum load
mode it becomes similar to that of stainless steel. This
may show that at the maximum load mode, the surface
temperature of the copper cathode becomes similar to
the surface temperature of the stainless steel cathode.
The direction of the curves for the dependences of
ozone concentration on time almost completely repeats
the dependences for the amount of charge transferred in
the discharge current pulse on time, with the exception
of the final section for copper cathodes at the maximum
load.
In the first minutes of operation, the pulse current is
rapidly increased, which is apparently associated with
gas heating at the cathode surface. At the partial load,
the growth is stabilized for copper cathodes much earli-
er than for stainless steel cathodes. This can be caused
by lower temperature of copper cathodes. An interesting
feature of the maximum load mode is the decrease in the
pulse current over time. As can be seen from the de-
pendence for the pulse current of copper cathodes, this
is a threshold effect, since it starts after 40 minutes of
PCR operation and is clearly visible. For stainless steel
cathodes, the conditions for the decrease in the pulse
current are formed in the first minutes of operation, so
the initial increase in the pulse current is directly re-
placed by a smooth decrease. In general case, heating
should lead to the increase in the current, since the gas
density is decreased during heating, and the value of the
reduced electric field is increased respectively, making
the discharge processes more intense. The threshold
nature of the effect shows that a new mechanism chang-
ing the discharge pattern is activated. For stainless steel
cathodes, this threshold is reached much earlier than for
copper cathodes. It can be assumed that this is due to the
peculiarity of the PCR power supply. In this experiment,
the HV pulsed power supply is a sequence of HV pulses
with the amplitude of ~ 10 kV against bias voltage,
which is ~ 500 V. The bias power supply voltage is used
to remove the volume charge accumulated during the
discharge current pulse from the discharge gap. This
makes it possible to significantly increase the operating
frequency in comparison with the HV pulsed power
supply only. Under the normal conditions, this voltage
is insufficient to maintain a self-sustained gas discharge.
A possible explanation for the decrease in the pulse
current over time is that the cathode heating in a thin
layer becomes such that the magnitude of the reduced
electric field, during the time between HV pulses, be-
comes sufficient to maintain the gas-discharge processes
at a certain low-intensity level. Thus, the bias voltage,
on the one hand, helps to remove the space charge
formed during the current pulse from the discharge gap,
and on the other hand, it itself becomes the cause for the
emergence of new one. The negative space charge gen-
erated during the time between the HV pulses is present
in the discharge gap at the time of the next voltage pulse
and screens the electric field generated at the cathode
during the HV pulse. This leads to the decrease in the
pulse current, and may lead to the gas discharge transi-
tion into a spark. For stainless steel cathodes, the heat-
ing of corona surface to a threshold level occurs rather
quickly due to a low thermal conductivity of stainless
steel. The fact that copper cathodes are heated to a
threshold level is explained by the fact that the structur-
al element of the PCR on which the cathode sections are
located is made of stainless steel; during operation, it is
heated from the copper cathode sections, and the heat
flux from the corona surface to the structural elements is
gradually decreased. As a result, the surface temperature
of copper cathode is increased, and the same happens
for stainless steel cathodes. In case of copper cathodes,
this effect can be eliminated by cooling the structural
elements. In case of stainless steel cathodes, cooling of
the structural elements does not make sense since the
drop in the pulse current is due to the low heat dissipa-
tion of the cathode material itself.
CONCLUSIONS
In the paper, the differences in the parameters of the
pulsed corona in oxygen for stainless steel and copper
cathodes are shown. The amount of charge carried in
one discharge current pulse for stainless steel cathodes
at the partial load is 15% higher than for copper cath-
odes at the same voltage pulse amplitude. This serves as
an indirect confirmation of the higher value for the
reduced electric field E/N in the generation zone, as a
result of the increased temperature. Ozone production
efficiency of the stainless steel electrode system is less
than 25% in comparison with copper cathodes at the
maximum load, and 60% at the partial load. This may
also be due to the increased temperature of corona sur-
face for the cathode. The results obtained show that for
more efficient ozone synthesis, in addition to using
cathodes made of materials with higher specific thermal
conductivity, forced cooling of the entire cathode sys-
tem is also required.
REFERENCES
1. V.I. Golota, G.V. Taran, AA. Zamuriev. Develop-
ment of ozone-dynamic technology for processing
used tyres // Problems of Atomic Science and Tech-
nology. Series “Plasma Electronics and New Meth-
ods of Acceleration”. 2015, № 4(98), р. 310-314.
2. V.I. Golota, G.V. Taran, A.A. Zamuriev,
P.O. Opalev, D.V. Kudin. Improvement of ozone-
dynamic methodfor used tire recycling // Ecology
and Industry. 2017, № 1 (50), p. 94-99.
3. L.F. Dolina. New methods and equipment for the
disinfection of waste water and natural waters. Dne-
propetrovsk: “Continent”, 2003, 218 p. ISBN-996-
7086-29-2.
4. O.V. Bolotov, V.I. Golota, Y.V. Sitnikova. Meas-
urement of rotational temperature of molecular ni-
trogen in the anode area of negative corona in air
under trichel pulse mode // Problems of Atomic Sci-
ence and Technology. 2018, № 4, p. 200-203.
Article received 06.10.2021
ISSN 1562-6016. ВАНТ. 2021. № 6(136) 98
ВЛИЯНИЕ МАТЕРИАЛА КАТОДА НА ХАРАКТЕРИСТИКИ ИМПУЛЬСНОЙ ОТРИЦАТЕЛЬНОЙ
КОРОНЫ В КИСЛОРОДЕ
В.И. Голота, Б.Б. Кадолин, Г.В. Таран, И.А. Пащенко
Исследовано изменение во времени формы импульсов разрядного тока импульсной отрицательной коро-
ны в кислороде с медными катодами и катодами из нержавеющей стали для двух режимов горения разряда,
заключающееся в уменьшении амплитуды импульса и увеличении их длительности на полувысоте. Показа-
но, что для катодов из нержавеющей стали количество электрического заряда, переносимого в одном им-
пульсе разрядного тока, на 15% больше чем для медных катодов. Также показано, что в режиме максималь-
ной нагрузки величина заряда, переносимого в одном импульсе разрядного тока, со временем уменьшается
на 10% для обоих типов катодов. Показано, что в электродной системе с катодами из меди наработка озона
происходит на 25% более эффективно.
ВПЛИВ МАТЕРІАЛУ КАТОДА НА ХАРАКТЕРИСТИКИ ІМПУЛЬСНОЇ НЕГАТИВНОЇ
КОРОНИ В КИСНІ
В.І. Голота, Б.Б. Кадолін, Г.В. Таран, І.А. Пащенко
Досліджено зміну в часі форми імпульсів розрядного струму імпульсної негативної корони в кисні з мід-
ними катодами і катодами з нержавіючої сталі для двох режимів горіння розряду, що полягає в зменшенні
амплітуди імпульсу і збільшенні їх тривалості на напіввисоті. Показано, що для катодів з нержавіючої сталі
кількість електричного заряду, що переноситься в одному імпульсі розрядного струму, на 15% більше ніж
для мідних катодів. Також показано, що в режимі максимального навантаження величина заряду, що пере-
носиться в одному імпульсі розрядного струму з часом зменшується на 10% для обох типів катодів. Показа-
но, що в електродній системі з катодами з міді напрацювання озону відбувається на 25% ефективніше.
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