Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply
In the paper plasma density dynamic on the axis of Penning discharge with metal-hydride cathode in axial electron flow emission regime have been experimentally investigated. The ion-stimulated desorption influence on emissive characteristics of the source were studied. Sufficient plasma density incr...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Цитувати: | Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply / I.N. Sereda, A.F. Tseluyko, D.L. Ryabchikov, I.V. Babenko, Ya.O. Hrechko, V.A. Hetman // Вопросы атомной науки и техники. — 2015. — № 4. — С. 342-344. — Бібліогр.: 6 назв. — англ. |
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irk-123456789-1122012017-01-19T03:02:20Z Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply Sereda, I.N. Tseluyko, A.F. Ryabchikov, D.L. Babenko, I.V. Hrechko, Ya.O. Hetman, V.A. Приложения и технологии In the paper plasma density dynamic on the axis of Penning discharge with metal-hydride cathode in axial electron flow emission regime have been experimentally investigated. The ion-stimulated desorption influence on emissive characteristics of the source were studied. Sufficient plasma density increasing up to n ≈ 10¹⁰ cm⁻³ was established on the discharge axis when metal-hydride cathode was used. Comparable analysis of the plasma density dynamic under different ways of hydrogen supply was carried out. Експериментально досліджена динаміка густини плазми на осі розряду Пеннінгa з металогідридним катодом у режимі емісії аксіального потоку електронів. Вивчено вплив іон-стимульованої десорбції водню на емісійні характеристики джерела. Встановлено значне збільшення щільності плазми n ≈ 10¹⁰ cm⁻³ на осі розряду з металогідридним катодом. Проведено порівняльний аналіз динаміки щільності плазми при різних способах напуску водню в розрядний проміжок. Экспериментально исследована динамика плотности плазмы на оси разряда Пеннинга с металлогидридным катодом в режиме эмиссии аксиального потока электронов. Изучено влияние ион-стимулированной десорбции водорода на эмиссионные характеристики источника. Установлено значительное увеличение плотности плазмы n ≈ 10¹⁰ cm⁻³ на оси разряда с металлогидридным катодом. Проведен сравнительный ана-лиз динамики плотности плазмы при различных способах напуска водорода в ячейку. 2015 Article Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply / I.N. Sereda, A.F. Tseluyko, D.L. Ryabchikov, I.V. Babenko, Ya.O. Hrechko, V.A. Hetman // Вопросы атомной науки и техники. — 2015. — № 4. — С. 342-344. — Бібліогр.: 6 назв. — англ. 1562-6016 PACS: 52.80.Sm http://dspace.nbuv.gov.ua/handle/123456789/112201 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Приложения и технологии Приложения и технологии |
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Приложения и технологии Приложения и технологии Sereda, I.N. Tseluyko, A.F. Ryabchikov, D.L. Babenko, I.V. Hrechko, Ya.O. Hetman, V.A. Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply Вопросы атомной науки и техники |
| description |
In the paper plasma density dynamic on the axis of Penning discharge with metal-hydride cathode in axial electron flow emission regime have been experimentally investigated. The ion-stimulated desorption influence on emissive characteristics of the source were studied. Sufficient plasma density increasing up to n ≈ 10¹⁰ cm⁻³ was established on the discharge axis when metal-hydride cathode was used. Comparable analysis of the plasma density dynamic under different ways of hydrogen supply was carried out. |
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Article |
| author |
Sereda, I.N. Tseluyko, A.F. Ryabchikov, D.L. Babenko, I.V. Hrechko, Ya.O. Hetman, V.A. |
| author_facet |
Sereda, I.N. Tseluyko, A.F. Ryabchikov, D.L. Babenko, I.V. Hrechko, Ya.O. Hetman, V.A. |
| author_sort |
Sereda, I.N. |
| title |
Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply |
| title_short |
Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply |
| title_full |
Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply |
| title_fullStr |
Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply |
| title_full_unstemmed |
Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply |
| title_sort |
plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2015 |
| topic_facet |
Приложения и технологии |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/112201 |
| citation_txt |
Plasma parameters in pig with metal-hydride cathode under different ways of hydrogen supply / I.N. Sereda, A.F. Tseluyko, D.L. Ryabchikov, I.V. Babenko, Ya.O. Hrechko, V.A. Hetman // Вопросы атомной науки и техники. — 2015. — № 4. — С. 342-344. — Бібліогр.: 6 назв. — англ. |
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Вопросы атомной науки и техники |
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ISSN 1562-6016. ВАНТ. 2013. №4(86) 342
PLASMA PARAMETERS IN PIG WITH METAL-HYDRIDE CATHODE
UNDER DIFFERENT WAYS OF HYDROGEN SUPPLY
I.N. Sereda, A.F. Tseluyko, D.L. Ryabchikov, I.V. Babenko, Ya.O. Hrechko, V.A. Hetman
V.N. Karazin Kharkiv National University, Kharkov, Ukraine
E-mail: igorsereda@karazin.ua
In the paper plasma density dynamic on the axis of Penning discharge with metal-hydride cathode in axial elec-
tron flow emission regime have been experimentally investigated. The ion-stimulated desorption influence on emis-
sive characteristics of the source were studied. Sufficient plasma density increasing up to n ≈ 1010 cm-3 was estab-
lished on the discharge axis when metal-hydride cathode was used. Comparable analysis of the plasma density dy-
namic under different ways of hydrogen supply was carried out.
PACS: 52.80.Sm
INTRODUCTION
Developing of plasma devises which are need no ex-
ternal sources of plasma-forming material is the great
interest for modern science. In case of hydrogen using
as working gas the metal-hydride cathode applying is
perspective. Such alloys are able to reversibly store hy-
drogen with following it’s desorption to a consumer.
Together with compactness and safety of hydrogen stor-
age it allows to locally supply hydrogen in activated
state at the discharge area of interest [1]. Hydrogen de-
sorption is determined mainly by thermal impact due to
discharge current. However a number of experiments
carried out on Penning discharge with metal-hydride
cathodes (MH-cathodes) revealed sufficient differences
in discharge working compared to ones where the cath-
odes did not form hydride phases [2 - 5]. So, the addi-
tion discharge regime with axial electron emission was
revealed in [2]. In [3] the influence of metal-hydride
cathode on electron emission was investigated. In [4]
the experimental simulation of hydrogen desorption by
the way of hydrogen supply through the cathode of spe-
cial design was carried out. And in [5] the possibility of
discharge working only on desorbed from metal-hydride
hydrogen due to ion stimulation processes was investi-
gated. The paper is continuation of the experiments and
devoted to investigation and generalization of plasma
parameters of Penning discharge with MH-cathode un-
der different ways of hydrogen supply.
1. EXPERIMENTAL SETUP
The experimental investigations were carried out on
penning-type discharge cell represented in Fig. 1.
Fig. 1. The scheme of discharge cell
1 – anode; 2 – MH-cathode; 3 – cathode-holder;
4 – thermocouple; 5 – cathode-reflector; 6 – collector;
7 – Langmuir probes
In experiments three types of cathodes were used.
First one was MH-cathode pressed from powder mix-
ture of saturated with hydrogen Zr50V50Hx alloy and
copper stuff with initial saturation of hydrogen about
900 cm3 at normal conditions. It was just set in dis-
charge. Second one was the same MH-cathode but with
water-cooling and third one was copper cathode of spe-
cial design with hydrogen supply for simulation of hy-
drogen desorbtion. The cathode-reflector was made
from copper and has a hole at the center 0.5 cm in di-
ameter. In check experiments two solid copper cathodes
were used. Behind the hole in cathode-reflector a collec-
tor was set.
In simulation of hydrogen desorbtion experiments
balloon hydrogen was locally fed through the thin holes
in working surface of copper cathode. The ratio between
local (through cathode) and additional (in vacuum
chamber) flows of supplied hydrogen as well as intensi-
ty of external magnetic field were pick out the same as
in [2] at third regime of discharge with MH-cathode.
For plasma parameters investigation two Langmuir
probes 4 mm in length and 0.3 mm in diameter were
used (7). They were set in the axis of the discharge in a
half distance between anode-cathode. The cathodes
were under grown potential, on the anode positive po-
tential was supplied.
The residual pressure in vacuum chamber not ex-
ceeds 5⋅10-6 Torr. The investigations were carried out at
the pressure of 10-6…10-4 Torr. Working pressure high-
er than residual one was set by initial balloon hydrogen
feeding in to vacuum chamber.
2. RESULTS AND DISCUSSION
The typical collector currents in case of the dis-
charge worked only on desorbed from MH-cathode hy-
drogen are presented in Fig. 2. One can see the dis-
charge behavior does not sufficiently change from the
previous experiments with the MH-cathode with addi-
tional external hydrogen supply in vacuum chamber [5].
The discharge is still characterized by three working
regime. The first one is with electron yield
(Ud ≈ 1…2.5 kV). The second one is with ion yield
(Ud > 2.4 kV) and the third one – again with electron
yield (Ud > 3.5 kV). Such a behavior was typical in the
range of magnetic field changing from 700 up to
1000 Oe. These regimes were in detail described in [3,
4] and concerned with oscillation processes in anode
layer. There is was no 3rd regime when both copper
cathodes had used (curve 3’). Simultaneous MH cathode
cooling was used for pressure stabilizing and did not
influence on collector current.
1 2
3
4
water
5 6
7
7
ISSN 1562-6016. ВАНТ. 2013. №4(86) 343
1 2 3 4 5 6
-60
-50
-40
-30
-20
-10
0
10
20 3
2
I co
l , µ
A
Ud, kV
1
Fig. 2. Dependence of collectors current on discharge
voltage at different cathodes, P=5·10-6 Torr, H=1 kOe.
1 – MH cathode; 2 – water-cooled MH cathode;
3 – check experiment
The first two regimes of discharge working are well
known [2], so the main attention in the paper was de-
voted to third regime. This regime starts only in case of
saturated with hydrogen MH-cathode applying [4]. The
plasma density on the discharge axis sufficiently rises.
And exactly in third regime this process is the most pro-
nounced.
The fact of interest when addition MH-cathode cool-
ing leads to not only hydrogen working pressure stabi-
lizing, but also provides uniform plasma density profile
along the axis of discharge cell (Fig. 3, curve 3) despite
of intense hydrogen flow only by the MH-cathode side.
The curve of plasma density by the cathode-reflector is
not present because of it almost full overlap with
curve 3. At the same time if the MH-cathode does not
cooling, the plasma density gradient aside MH-cathode
will appears and it rises along discharge current increas-
ing (see Fig. 3, curves 1 and 2). It is in good agreement
with previous experiments because apart from ion-
stimulated desorption of hydrogen from the MH-
cathode surface there are mechanisms of thermal de-
composition of hydride phases and hydrogen desorbed
from the material volume [1, 2].
3,0 3,5 4,0 4,5 5,0 5,5 6,0
0
2
4
6
8
10
n*
10
9 cm
-3
Ud , kV
1
2
3
Fig. 3. Plasma density on the axis of PIG with different
cathodes depending on discharge voltage,
P = 5·10-6 Tor, H = 1 kOe.
1 and 2 – by the MH-cathode and by the opposite side
correspondingly; 3 – by the MH water-cooled cathode
In case of hydrogen supply due to only ion-
stimulated processes the desorption velocity determines
only by discharge current and adjusts for needful plasma
density in the discharge cell providing. The data about
experiments with two copper cathodes are not presented
because on this stage the experiments were carried out
only on residual pressure under hydrogen desorption
only from MH-cathode.
Fig. 4 demonstrates the characteristic curves of
plasma density depending on magnetic field for dis-
charge voltage 3.5 kV – collector current compensation
and for 5.0 kV – negative collector current (see Fig. 2).
One can see there is a trend for plasma density decreas-
ing in the range of magnetic field of 600…800 Oe.
When magnetic field rises in regime of collector current
compensation (Ud = 3.5 kV) the trend kept on, but at
Ud = 5.0 kV the density increases. But plasma density in
case of cooled MH-cathode is sufficiently lower, then
for MH-cathode without simultaneous cooling. Such a
behavior is obviously due to nonlinear dependency of
discharge current on magnetic field under the circum-
stances of anode layer instability development [6].
600 700 800 900 1000
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
5,5
6,0
6,5
7,0
7,5
MH w/c cathode
MH w/c cathode
MH-cathode
U d =
5
.0
k
V
n*
10
9 c
m
-3
H, Oe
U d =
3
.5
k
V
MH-cathode
Fig. 4. Plasma density on the axis of PIG
with different cathodes depending on magnetic field
intensity, P = 5·10-6 Torr
3,0 3,5 4,0 4,5 5,0 5,5 6,0
0
2
4
6
8
10
12
5
4
3
2
n*
10
9 , c
m
-3
Ud , kV
1
Fig. 5. Plasma density on the axis of PIG with different
cathodes depending on discharge voltage,
P = 3·10-5 Torr, H = 1 kOe.
1 and 2 – by the MH-cathode and by the opposite side
correspondingly; 3 – by the MH water-cooled cathode;
4 – by the cathode with balloon H2 supply;
5 – check experiment
In Fig. 5 the summary pattern of plasma density de-
pendence on discharge voltage is presented for different
ways of hydrogen supply. Here again hydrogen supply
was carried out by the side of a cathode but there was
also general hydrogen supply into the vacuum chamber.
The behavior of curves 1, 2 and 3 is the same as pre-
sented above in Fig. 3 and explained the same reasons
ISSN 1562-6016. ВАНТ. 2013. №4(86) 344
then for experiments on residual pressure. Curve 4 cor-
responds to desorption simulation experiment by the
way of hydrogen supply through the cathode of special
design. The experimental set up and problem statement
are described in detail in [4]. Curve 5 corresponds to
check experiments with two copper cathodes.
One can see that independently on the way of hy-
drogen supply the highest values of the plasma density
are achieved at MH-cathode applying. Also it could be
concluded that MH-cathode applying increases the effi-
ciency of plasma forming due to mutual influence of
discharge current on hydrogen desorption in non equi-
librium state. So, MH-cathode is not only the local gas
generator, but also increases working efficiency of the
plasma device in general.
The electron temperature was about 25 eV and au-
thors did not observe any sufficient differences in elec-
tron temperature behavior under different ways of hy-
drogen supply. The same could be said about plasma
and floating potential, which were investigated in [3].
CONCLUSIONS
Thus, at discharge working on hydrogen desorbed
from MH-cathode the plasma density sufficiently in-
creases. The highest values of the density n ≈ 1010 cm-3
are achieved by the MH-cathode without simultaneous
cooling dependingless on initial gas environmental.
From the opposite side by the cathode-reflector the
plasma density is some lower so the gradient towards
from the MH-cathode to cathode-reflector occurs. The
additional MH-cathode cooling decreases hydrogen
desorption velocity, and the plasma density takes the
lower values then in above case and the density gradient
along the axis practically disappears. At working on
balloon hydrogen dependingless on the way of its sup-
ply there is no third regime with axial electron emission
and plasma density sufficiently lower.
REFERENCES
1. Yu.F. Shmal’ko, Ye.V. Klochko, N.V. Lototsky.
Influence of isotopic effect on the shift of the ioniza-
tion potential of hydrogen desorbed from metal hy-
dride surface // Int. J. Hydrogen energy. 1996, v. 21,
p. 1057-1059.
2. I.A. Afanas’eva, V.N. Borisko, Ye.V. Klochko,
A.F. Tseluyko. Current compensation of hydrogen
ion beam extracted from PIG with metal-hydride
cathode // Problems of Atomic Science and Technol-
ogy. Series «Plasma Physics». 2007, № 1, p. 191.
3. Ye.V. Klochko, D.L. Ryabchikov, I.N. Sereda,
A.F. Tseluyko. Influence of metal-hydride cathode
on electron yield from PIG // Problems of Atomic
Science and Technology. Series «Plasma Electronics
and New Acceleration Methods». 2010, № 4, p. 226.
4. I.V. Borgun, D.L. Ryabchikov, I.N. Sereda,
A.F. Tseluyko. Experimental simulation of metal-
hydride cathode working in Penning discharge //
Problems of Atomic Science and Technology. Series
«Plasma Physics». 2013, № 1, p. 228-230.
5. A.V. Agarkov, D.L. Ryabchikov, I.N. Sereda,
A.F. Tseluyko. PIG with metal-hydride cathode un-
der ion-stimulated desorbtion of hydrogen // Prob-
lems of Atomic Science and Technology. Series
«Plasma Electronics and New Acceleration
Methods». 2013, № 4, p. 301-303.
6. W. Khauer. Diocotron Instability in Plasmas and
Gas Discharges // J. Appl. Phys. 1966, v. 37, № 2,
p. 602.
Article received 14.04.2015
ПАРАМЕТРЫ ПЛАЗМЫ В РАЗРЯДЕ ПЕННИНГА С МЕТАЛЛОГИДРИДНЫМ КАТОДОМ
ПРИ РАЗНЫХ СПОСОБАХ НАПУСКА ВОДОРОДА
И.Н. Середа, А.Ф. Целуйко, Д.Л. Рябчиков, Е.В. Бабенко, Я.О. Гречко, В.А. Гетман
Экспериментально исследована динамика плотности плазмы на оси разряда Пеннинга с металлогидрид-
ным катодом в режиме эмиссии аксиального потока электронов. Изучено влияние ион-стимулированной
десорбции водорода на эмиссионные характеристики источника. Установлено значительное увеличение
плотности плазмы n ≈ 1010 см-3 на оси разряда с металлогидридным катодом. Проведен сравнительный ана-
лиз динамики плотности плазмы при различных способах напуска водорода в ячейку.
ПАРАМЕТРИ ПЛАЗМИ В РОЗРЯДІ ПЕННІНГA З МЕТАЛОГІДРИДНИМ КАТОДОМ
ПРИ РІЗНИХ СПОСОБАХ НАПУСКУ ВОДНЮ
І.М. Середа, О.Ф. Целуйко, Д.Л. Рябчиков, Є.В. Бабенко, Я.О. Гречко, В.А. Гетьман
Експериментально досліджена динаміка густини плазми на осі розряду Пеннінгa з металогідридним ка-
тодом у режимі емісії аксіального потоку електронів. Вивчено вплив іон-стимульованої десорбції водню на
емісійні характеристики джерела. Встановлено значне збільшення щільності плазми n ≈ 1010 см-3 на осі роз-
ряду з металогідридним катодом. Проведено порівняльний аналіз динаміки щільності плазми при різних
способах напуску водню в розрядний проміжок.
1. EXPERIMENTAL SETUP
2. RESULTS AND DISCUSSION
CONCLUSIONS
|