Investigation of high-current plasma opening switch at low gas pressure
The high-current plasma opening switch (POS), combined with the inductive energy storage, can be applied in the power electron accelerator of nano- and microsecond operation. The POS discharge characteristics should be stabilized and controlled. In the present work the POCS behaviour in dependence o...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2000
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| Cite this: | Investigation of high-current plasma opening switch at low gas pressure / V.B. Yuferov, E.I. Skibenko, I.N. Onishchenko, V.G. Artyuch, O.S. Druy // Вопросы атомной науки и техники. — 2000. — № 2. — С. 100-102. — Бібліогр.: 2 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860200744107376640 |
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| author | Yuferov, V.B. Skibenko, E.I. Onishchenko, I.N. Artyuch, V.G. Druy, O.S. |
| author_facet | Yuferov, V.B. Skibenko, E.I. Onishchenko, I.N. Artyuch, V.G. Druy, O.S. |
| citation_txt | Investigation of high-current plasma opening switch at low gas pressure / V.B. Yuferov, E.I. Skibenko, I.N. Onishchenko, V.G. Artyuch, O.S. Druy // Вопросы атомной науки и техники. — 2000. — № 2. — С. 100-102. — Бібліогр.: 2 назв. — англ. |
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| container_title | Вопросы атомной науки и техники |
| description | The high-current plasma opening switch (POS), combined with the inductive energy storage, can be applied in the power electron accelerator of nano- and microsecond operation. The POS discharge characteristics should be stabilized and controlled. In the present work the POCS behaviour in dependence on gas pressure, kind of gas, time input of plasma density, its spatial distribution, extent of plasma ionization, its averaged charge has been investigated to attain the commuted current enhancement.
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| first_indexed | 2025-12-07T18:10:59Z |
| format | Article |
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INVESTIGATION OF HIGH-CURRENT PLASMA OPENING SWITCH
AT LOW GAS PRESSURE
V.B. Yuferov, E.I. Skibenko, I.N. Onishchenko, V.G. Artyuch, O.S. Druy
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
The high-current plasma opening switch (POS), combined with the inductive energy storage, can be applied in
the power electron accelerator of nano- and microsecond operation. The POS discharge characteristics should be
stabilized and controlled. In the present work the POCS behaviour in dependence on gas pressure, kind of gas, time
input of plasma density, its spatial distribution, extent of plasma ionization, its averaged charge has been investigated
to attain the commuted current enhancement.
PACS: 52.75.Kq, 52.75.Pv
I. INTRODUCTION
The obvious advances in deriving and researching
heavy-current pulses of electron current and in clearing
up the physical operation principles of electron
accelerators of a direct action with the plasma opening
switch are reached. However, it is expedient and
necessary to research the physical and engineering
peculiarities in creation and operation of similar devices
in order to realize calculated modes of their operation.
In the present work the experimental results of research
on some features of the electron accelerator DI
operation with the plasma opening switch (POS), in
particular, filling the discharge gap with plasma at low
gas pressure, are given and the switch efficiency is
determined.
II. EXPERIMENTAL SETUP AND
METHODS
The schematic diagram of the small-sized
accelerating installation DI [1] with a plasma current
switch is represented in Fig. 1. It comprises: vacuum
chamber having ∅200 mm and 350 mm height with a
set of electrodes, plasma guns and magnetic coils,
generator of pulsed current (GPC), power sources of
plasma guns and magnetic field, units of start-up and
synchronization, noise protection tools, diagnostic
infrastructure, pumping post. The compactness of the
accelerator DI is illustrated by the weights of following
components: vacuum chamber –15 kg, GPC - 200 kg
(140 kg), feed of plasma guns - 46 kg (2 kg), feed of
magnetic field - 12 kg (3 kg), units of start-up and
synchronization - 5 kg, noise-protection and diagnostic
tools - 7 kg, pumping post - 30 kg, measuring equipment
- 28 kg, assembly frame - 17 kg. The total weight is
360 kg that makes the accelerator DI a convenient
device to transport. The transition to pulsed converters
of voltage allows to reduce essentially the mass of
feeding devices (see the figures in brackets) and the
final mass of the accelerating installation up to 200−
230 kg. Its overall dimensions are 180×120×60 cm.
Basic electric parameters of the accelerator DI by
primary circuits are the following: voltage at the central
electrode (cathode) up to 50 kV, capacity of the
accumu lating capacitor 3 µF, its inductance 40 nH,
inductance
Fig. 1. A schematic diagram of the accelerator DI:
1 - vacuum chamber; 2 - cathode; 3 - insulator; 4 -
anode; 5 - slit-like slots; 6 - diaphragm; 7 - central
electrode of a plasma gun; 8 - insulator of a plasma
gun; 9 - pumping branch pipe; 10 - pressure
transducers; 11 - packing ring.
of plasma current switch 122 nH, inductance of load
(diode) 5 nH, power supply voltage of plasma guns up
to 15 kV. The filling of discharge gap with plasma was
carried out using 12 plasma guns of planar types [2]
disposed uniformly in the equatorial plane of the
vacuum chamber. The installation of DI is provided with
the following tools of diagnostics: belts of Rogovsky for
measurement of switch current and load current of
accelerating diode, capacity divider for measurement of
voltage on the cathode, X-ray transmitters of integrated
and scintillation types, microwave interferometers at a
frequency of 35 GHz for measurement of plasma density
injected into the discharge gap with the help of plasma
100 ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2000, № 2.
Серия: Ядерно-физические исследования (36), с. 100-102.
guns and its spatial distribution, sensors for pulse
measurement of pressure in a phase of current
commutation and after that. In Fig. 2 the geometry and
the scheme of microwave investigation of plasma
injected outside in the area near the cathode, for
measuring its transversal sizes by microwaves reflection
are presented. As the plasma guns are located at the
vacuum chamber wall and the filling of a discharge gap
with plasma is performed from periphery to center, so
transversal size measuring is made from the reflecting
wall to the center (see the coordinate axis R in Fig. 2).
R.W..
Pl.
H.A. At.. P
D P.I.
0 R ∼ G
Fig. 2. Scheme of a microwave investigation of
plasma. G. - generator, P. - piston, D - detector, H.A. -
horn antenna, Pl. - plasma, R.W. - reflecting wall, At. -
attenuator, P.I. - phase inverter
III. EXPERIMENTAL RESULTS
Measurement of injected plasma parameters, e.g.
change of density and linear sizes as a function of time
at n ≥ nc, can play an important role in determining the
moment of GIC switching relatively to the plasma gun
pulse, as well as in evaluating the total plasma amount in
the discharge gap and, consequently, the value of
commuted current.
In Fig. 3а the transversal size (radius) formation
(front) with the critical density nc ≥ 1.8⋅1013 cm-3 as a
function of time is shown.
0 5 10 15 20 25
0
10
20
30
40
50
60
R
, m
m
t, µ s
Fig. 3a. The time dependence of the critical plasma
front.
The data obtained allow evaluating the driving
velocity of plasma front with a critical density (i.e.
reflecting layer) in the discharge gap. At the initial stage
of plasma injection the velocity of reflecting layer
propagation is maximum and equal to 7.2⋅105 cm./s. As
the reflecting layer extends (displacement of the plasma
front) its temperature and, respectively, the driving
velocity drops up to a value of 3.4⋅105 cm./s. Proceeding
from an average value of a velocity of plasma front
propagation ~ 5⋅105 cm./s, we obtain the time of
discharge gap filling with plasma of nc ≥ 1.8⋅1013 cm-3
being equal to ~ 15 µs, that approximately corresponds
to the magnitude of in-time delay switching between
GIC and plasma guns defined experimentally. This
conclusion is confirmed also by the radial distribution of
plasma density (Fig.3b) in the discharge gap in an
instant t = 2-4 µs after switching the plasma guns pulse
(curve 1), t= 12 µs (curve 2) and t = 20 µs (curve 3).
0 10 20 30 40 50 60
4
6
8
10
12
14
16
18 n1
n2
n3
n
х
10
-1
2 , c
m
-3
R, mm
Fig. 3b. Plasma and critical density by three time
moments.
Apart from this the dependence of the lifetime of
plasma with a critical density of nc ≥ 1.8⋅1013 см-3 on the
plasma gun voltage is established. This time consists of
~ 25 µs under operation of 4 guns, and ~ 50 µs for 12
guns. Besides, the dependence of n = f (R) indicates
precisely that the plasma bunch injected by a gun,
consists of two parts: fast one of a low-density n ~ 5⋅
1012 cm-3 and slow one of a density n ≥ 1.8⋅1013 cm-3.
The fast low-dense plasma fills the discharge gap during
several µs after the plasma gun firing; the dense plasma
fills it 10-15 µs later. Apparently, just the fast part of the
bunch ionizes the neutral gas filling the discharge gap
and the chamber of the POS.
Fig.4 shows the distribution of n -number of pulses
by k- multiplicity of voltage multiplication in a series of
55 pulses for various number of operating plasma guns
(4 or 12). As is seen, the increase of a number of plasma
guns from 4 up to 12 results in appreciable increase of
the average factor of voltage multiplication, and also in
reduction of its scattering from pulse to pulse. The
maximum value of voltage in the given pulse series was
378 kV at GIT voltage up to 37 kV.
The maximum value of the load (diode) power was
4.92⋅1010 W. In this case Umax=360 kV, Imax=136.7 kA,
t=30 ns. In Fig. 5 a part α of the GIC maximum current,
commuted into the load, i.e. into the electron diode, is
101
represented as a function of the energy capacity of
plasma guns. In the given series of pulses the maximum
value of GIC current was 129 kA. It is seen, that
increasing the number of plasma guns from 4 (curve 1)
to 12 (curve 2) leads to noticeable (above 25-30%)
growth of the commuted current value, that, apparently,
is connected with increasing the amount and density of
plasma in the discharge gap, as well as with changing its
spatial distribution along the clearance to more uniform
case. Even the more significant (by 50%) increasing of
the commuted current was observed under the POS
chamber filling with argon at pressure 1.5⋅10-3 Torr
(curve 3). The argon presence results in increasing the
density and the life time of plasma due to the higher
values of ionization cross-section in the energy range
20-30 eV, i.e. near to ionization potentials and, as a
consequence, leads to growth of the commuted current
value. Besides, the availability of argon, probably,
reduces the recombination velocity of primary plasma
injected from the outside, and, as a consequence the
lifetime of plasma in the discharge gap increases. Thus,
more effective means for increasing the commuted
current value in comparison with increasing the number
of plasma guns is the argon filling to low pressure. In
the greater extent this influences on the uniformity of the
discharge gap filling with plasma due to argon
ionization by electrons of primary plasma. The similar
effect was observed also for the presence of carbon
containing atmosphere (СО2, CO, СН4, С2Н2) in the
POS chamber.
0 2 4 6 8 10
0,0
0,1
0,2
0,3
0,4
0,5
1
2
n
k
Fig. 4. Distribution of voltage multiplication on a
number of plasma guns: 1 - 4 guns, 2 - 12 guns.
In Fig. 6 the experimental results of a research on
influence of a density of residual gases in the pos
chamber on the commuted current value (in terms of α)
are represented. It is seen, that the dependence α = f (n0)
has a threshold character. The switching of a current
begins at n0 ≥ 3.5⋅1012 cm-3, and at n0 ≥ 1⋅1013 cm-3 the
magnitude αi.e. The part of a maximum current of gic
commuted into the load, grows insignificantly (in limits
of 10 %).
IV. SUMMARY
From dependencies shown in Figs. 5 and 6 the only
conclusion follows that for increasing the commuted
current value of a decisive importance is the creation
and maintenance of conditions for uniform plasma
density distribution in the discharge gap. It can be
0 50 100 150 200 250
0,2
0,4
0,6
0,8
1,0
A1
A2
A3
α
W, J
Fig. 5. The load current vs the energy capacity of
injected plasma for various number of guns and Ar
presence.
0 2 4 6 8 10
0,3
0,4
0,5
0,6
0,7
0,8
α
n х 10-13, cm-3
Fig. 6. The load current vs the gas density
achieved by increasing the number of plasma guns (4 to
12), i.e. increasing the amount of plasma injected from
the outside (curve 1 and 2 in Fig. 4), filling argon into
the POS chamber (curves 3 and 2, 3 and 1 Fig. 5) or
increasing the residual gas density in the discharge gap
(Fig. 6).
102
REFERENCES
1.V.G. Artyukh, Е.I. Skibenko, Yu.V. Tkach,
V.B. Yuferov. Research on a heavy-current plasma
switch, Preprint KIPT 89 - 28, Kharkov, 1989, 12 p.
2.V.G. Artyukh, Е.I. Skibenko, Yu.V. Tkach,
V.B. Yuferov. Plasma - vacuum performances of
the fast current switch. Preprint KIPT 94 - 12,
Kharkov, 1994, 8 p.
103
Investigation of High-Current Plasma Opening SwiTch
at Low Gas Pressure
I. Introduction
II. Experimental setup and methods
III. Experimental results
In Fig. 6 the experimental results of a research on influence of a density of residual gases in the pos chamber on the commuted current value (in terms of ) are represented. It is seen, that the dependence = f (n0) has a threshold character. The switching of a current begins at n0 3.51012 cm-3, and at n0 11013 cm-3 the magnitude i.e. The part of a maximum current of gic commuted into the load, grows insignificantly (in limits of 10 %).
IV. Summary
References
|
| id | nasplib_isofts_kiev_ua-123456789-82273 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T18:10:59Z |
| publishDate | 2000 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Yuferov, V.B. Skibenko, E.I. Onishchenko, I.N. Artyuch, V.G. Druy, O.S. 2015-05-27T12:38:13Z 2015-05-27T12:38:13Z 2000 Investigation of high-current plasma opening switch at low gas pressure / V.B. Yuferov, E.I. Skibenko, I.N. Onishchenko, V.G. Artyuch, O.S. Druy // Вопросы атомной науки и техники. — 2000. — № 2. — С. 100-102. — Бібліогр.: 2 назв. — англ. 1562-6016 PACS: 52.75.Kq, 52.75.Pv https://nasplib.isofts.kiev.ua/handle/123456789/82273 The high-current plasma opening switch (POS), combined with the inductive energy storage, can be applied in the power electron accelerator of nano- and microsecond operation. The POS discharge characteristics should be stabilized and controlled. In the present work the POCS behaviour in dependence on gas pressure, kind of gas, time input of plasma density, its spatial distribution, extent of plasma ionization, its averaged charge has been investigated to attain the commuted current enhancement. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Тheory and technics of particle acceleration Investigation of high-current plasma opening switch at low gas pressure Исследование сильноточного плазменного открывающего ключа при низких давлениях газа Article published earlier |
| spellingShingle | Investigation of high-current plasma opening switch at low gas pressure Yuferov, V.B. Skibenko, E.I. Onishchenko, I.N. Artyuch, V.G. Druy, O.S. Тheory and technics of particle acceleration |
| title | Investigation of high-current plasma opening switch at low gas pressure |
| title_alt | Исследование сильноточного плазменного открывающего ключа при низких давлениях газа |
| title_full | Investigation of high-current plasma opening switch at low gas pressure |
| title_fullStr | Investigation of high-current plasma opening switch at low gas pressure |
| title_full_unstemmed | Investigation of high-current plasma opening switch at low gas pressure |
| title_short | Investigation of high-current plasma opening switch at low gas pressure |
| title_sort | investigation of high-current plasma opening switch at low gas pressure |
| topic | Тheory and technics of particle acceleration |
| topic_facet | Тheory and technics of particle acceleration |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/82273 |
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