The multifrequency low-voltage plasma-beam generator
The authors have submitted the experimental results concerning the excitation of multi-frequency oscillations in the beam-plasma generator based on the helical slow-wave structure. It is demonstrated that oscillations can be excited under the beam current up to 4 A, the accelerating voltage being up...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Zitieren: | The multifrequency low-voltage plasma-beam generator / V.S. Antipov, A.V. Arhipov, I.A. Bez’yazychny, I.V. Berezhnaya, E.A. Kornilov // Вопросы атомной науки и техники. — 2007. — № 1. — С. 116-118. — Бібліогр.: 6 назв. — англ. |
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irk-123456789-1105292017-01-05T03:04:15Z The multifrequency low-voltage plasma-beam generator Antipov, V.S. Arhipov, A.V. Bez’yazychny, I.A. Berezhnaya, I.V. Kornilov, E.A. Plasma electronics The authors have submitted the experimental results concerning the excitation of multi-frequency oscillations in the beam-plasma generator based on the helical slow-wave structure. It is demonstrated that oscillations can be excited under the beam current up to 4 A, the accelerating voltage being up to 4 kV at several frequencies within the range 0.6‑1.2 GHz in the quasi-continuous and continuous regimes. Представлено експериментальні результати по збудженню багаточастотних коливань у пучково-плазмовому генераторі на основі спіральної уповільнюючої структури. Продемонстровано можливість збудження коливань при струмі пучка до 4 А, прискорюючій напрузі до 4 кВ на декількох частотах у діапазоні 0,4-1,2 ГГц у квазінеперервному та неперервному режимах. Представлены экспериментальные результаты по возбуждению многочастотных колебаний в пучково-плазменном генераторе на основе спиральной замедляющей структуры. Продемонстрирована возможность возбуждения колебаний при токе пучка до 4 А, ускоряющем напряжении до 4 кВ на нескольких частотах в диапазоне 0,4-1,2 ГГц в квазинепрерывном и непрерывном режимах. 2007 Article The multifrequency low-voltage plasma-beam generator / V.S. Antipov, A.V. Arhipov, I.A. Bez’yazychny, I.V. Berezhnaya, E.A. Kornilov // Вопросы атомной науки и техники. — 2007. — № 1. — С. 116-118. — Бібліогр.: 6 назв. — англ. 1562-6016 PACS: 52 40 Mj http://dspace.nbuv.gov.ua/handle/123456789/110529 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Plasma electronics Plasma electronics |
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Plasma electronics Plasma electronics Antipov, V.S. Arhipov, A.V. Bez’yazychny, I.A. Berezhnaya, I.V. Kornilov, E.A. The multifrequency low-voltage plasma-beam generator Вопросы атомной науки и техники |
| description |
The authors have submitted the experimental results concerning the excitation of multi-frequency oscillations in the beam-plasma generator based on the helical slow-wave structure. It is demonstrated that oscillations can be excited under the beam current up to 4 A, the accelerating voltage being up to 4 kV at several frequencies within the range 0.6‑1.2 GHz in the quasi-continuous and continuous regimes. |
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Article |
| author |
Antipov, V.S. Arhipov, A.V. Bez’yazychny, I.A. Berezhnaya, I.V. Kornilov, E.A. |
| author_facet |
Antipov, V.S. Arhipov, A.V. Bez’yazychny, I.A. Berezhnaya, I.V. Kornilov, E.A. |
| author_sort |
Antipov, V.S. |
| title |
The multifrequency low-voltage plasma-beam generator |
| title_short |
The multifrequency low-voltage plasma-beam generator |
| title_full |
The multifrequency low-voltage plasma-beam generator |
| title_fullStr |
The multifrequency low-voltage plasma-beam generator |
| title_full_unstemmed |
The multifrequency low-voltage plasma-beam generator |
| title_sort |
multifrequency low-voltage plasma-beam generator |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2007 |
| topic_facet |
Plasma electronics |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/110529 |
| citation_txt |
The multifrequency low-voltage plasma-beam generator / V.S. Antipov, A.V. Arhipov, I.A. Bez’yazychny, I.V. Berezhnaya, E.A. Kornilov // Вопросы атомной науки и техники. — 2007. — № 1. — С. 116-118. — Бібліогр.: 6 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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116 Problems of Atomic Science and Technology. 2007, 1. Series: Plasma Physics (13), p. 116-118
THE MULTIFREQUENCY LOW-VOLTAGE PLASMA-BEAM
GENERATOR
V.S. Antipov, A.V. Arhipov, I.A. Bez’yazychny, I.V. Berezhnaya, E.A. Kornilov
NSC “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
The authors have submitted the experimental results concerning the excitation of multi-frequency oscillations in the
beam-plasma generator based on the helical slow-wave structure. It is demonstrated that oscillations can be excited
under the beam current up to 4 A, the accelerating voltage being up to 4 kV at several frequencies within the range
0.6-1.2 GHz in the quasi-continuous and continuous regimes.
PACS: 52 40 Mj
1. INTRODUCTION
The microwave devices, capable of working
simultaneously in a broad frequency range [1] are of the
great interest for systems of the ground-control and
satellite communication. Other technical applications of
such devices are possible as well. For the first time the
multi-frequency excitation of the slow wave structure has
been theoretically examined in [2,3]. It has been
demonstrated the following. If the electron beam current
increases, the generation stationary regime becomes
replaced by the regime of auto modulation and
stochasticity. In [4], the analytical results are proved to be
true experimentally. The use has been made of a
backward-wave tube (the corrugated waveguide) of the
power level up to 100 kW. The accelerating voltage
makes 70 kV, the beam current is up to 35 A. The pulse
duration made 10 sµ and the frequency - 8 GHz. In [5],
the analogous experiments were carried out also with a
slow-wave structure of the interdigitally-loaded system
(the accelerating voltage was up to 250 V, and the beam
current was up to 100 mA).
A hybrid slow-wave structure is one of those where
the excitation of intensive oscillations in a broad
frequency band is possible.
The aim of the given work is the experimental
attempts at finding the possibility of the multi-frequency
oscillation excitation. For this purpose, it is chosen a
model of a broadband and low-voltage beam-plasma
generator, based on a helical slowing-down system.
2. DESCRIPTION OF THE INSTALLATION
AND TECHNIQUES OF MEASUREMENTS
The block diagram of the installation, where the
excitation of multi-frequency oscillations was carried out,
is given in Fig.1. This scheme contains the following
elements: an electron gun of the magnetron type (1), a
slowing-down system of the helical type (6, 9), a collector
(21), a solenoid (16) and a system that controls the
working gas pressure.
An annular electron beam of the external diameter 28
mm and the thickness 4 mm is formed with the gun.
Acceleration of electrons is realized by supplying to the
cathode assembly either of the constant or the pulse
negative voltage 2-4 kV (of the duration up to 0.4 ms).
The beam maximum current makes 4 A.
The beam transportation is carried out in the
longitudinal magnetic field. The solenoid consists of the
two sections. It has permitted us to generate optimal
magnitudes of the magnetic field strength (up to 0.08 T)
along the generator longitudinal axis and in the area of the
electron gun. In the vicinity to the electron gun, the
magnetic field strength is prescribed by the accelerating
voltage. Besides, it is necessary to form the annular
electron beam of the dimensions stipulated. The current
precipitating on the slow-wave structure must be minimal.
Fig.1. The installation block diagram
The typical pulses of voltage and current are depicted
in Fig.2.
0.0 0.2 0.4 0.6 0.8
-4.0
-3.0
-2.0
-1.0
0.0
1
2
3
U(kV),I(A),P(r.,u.)
t, ms
Fig.2. The voltage pulse (1); the beam current pulse (2);
the microwave oscillation envelope (3)
The generator consists of two slow-wave sections of
the helical type. They are connected with the area of the
117
beam-plasma interaction. To the first section input, a short
(3) is connected. It provides the oscillation reflection in a
broad band of frequencies. The first section output is
connected with the second section input via the phasor.
The second section output is loaded with the matched
load via a coaxial tuners (10).
The measuring equipment is connected into the track
via the directed microwave couplers. From the coupler
(11), the signal is transmitted to the detector (8). This is
intended for measuring the microwave oscillation
envelope with the oscillograph (7) or the analogous-
digital transformer (4). Simultaneously the signal is also
transmitted to the wavemeter (18) as well as to the
integrator-amplifier (15) and the plotter (19). Oscillations
in various sections of the microwave pulse envelope are
registered with the fast-response oscillograph (13).
3. THE EXPERIMENT
The authors have experimentally investigated regimes
of multi-frequency oscillation excitation. The oscillation
spectra and their power have been measured under
various conditions – i.e., the values of accelerating
voltages, beam currents, the plasma densities (the
working gas pressure) and the magnetic field voltage. The
frequency spectrum and the fact of the simultaneous
excitation of several frequencies have been indicated by
Fourier analysis given to microwave oscillation
realization.
If the gas pressure is low in the system, the beam-
plasma discharge is not developing. The number of the
wave-types excited is prescribed by the quality of the
concordance between helixes, feeders and loadings. The
electron beam current can exceed the starting current for
each type of the waves and the beam energy when the
electron velocity is close to the wave phase velocity in the
decelerating structure. In this case, the oscillations are
excited under the condition of the beam-wave distributed
interaction.
Under the gas pressure 2⋅10-6 mm Hg, the starting
current values I have been determined. Under these
values arise single-frequency oscillations (see Fig. 3 a).
The amplitude of these oscillations increases with the
current increase.
1 S(f)
0
0.4 0.8 f, GHz
1 S(f)
0
b 0.4 0.8 f, GHz
Fig.3. Oscillograms and microwave spectra of the output
signal under the low pressure without plasma:
a) the stationary regime; b) the auto modulation regime
Under the accelerating voltages about 2-4 kV, the
starting current is within 0.4-0.6 A. Heightening of the
beam current up to 2.5-3 A results in the substitution of
the automodulation regime for the single-frequency
generation regime (see Fig. 3 b). Besides the basic
frequency 1.08 GHz, the spectrum contains the lateral
components 1.0 and 1.16 GHz. When I/I ≈ 5, the level of
components makes -15 dB. These results are in the rather
good agreement with the data in [5]. The beam current
heightening up to 4 A (it is the limiting current for the gun
used) has not caused changes in the auto modulation
nature. Besides, no substantial increase in the lateral
components is fixed. According to [3], this regime is
realizable when the beam current 10-15 times exceeds the
threshold current. The oscillation power at the output
makes about 300-400 Wt.
Heightening of the working gas pressure causes the
generation of plasma and the formation of the helical-
plasma waveguide. The device can operate in the plasmic
regime if the following ratio was realized:
ω ω ω ωb e eh
2 2 2 2<< < < .
Here ωb implies the beam electron frequency; ω is the
working frequency; ω is the electron plasma frequency;
ωeh is the electron cyclotron frequency. Our installation
operates in this regime under the gas pressure
5⋅10-5- 5⋅10-4 mm Hg.
Under the same accelerating voltages, the starting
current diminishes 2-3 times. With the beam current like
this, the oscillations are single-frequency. The higher the
beam current is, for the more amount of wave types there
arise conditions for the current exceeding of the starting
current value for the given wave type. As the result, in the
system a spectrum is excited, which consists of several
frequencies. Experimentally it was observed the
microwave excitation within the range of 0.4 - 1.5 GHz.
The works was fulfilled with different parameters of the
beam, plasma and the magnetic field strength. As the
examples, in Fig.4 a, b one can see oscillograms and
spectra of the two- and three frequency oscillations.
1 S(f)
0
0.4 0.8 f, GHz
1 S(f)
0
b 0.4 0.8 f, GHz
1 S(f)
0
c 0.4 0.8 f, GHz
Fig.4. Oscillograms and microwave spectra of the output
signal in the beam-plasma regime
118
It is necessary to mark, that in the presence of plasma
the power spectral density can be made rather uniform for
different frequencies. If the beam currents make 3 - 4 A,
the oscillation power at the output makes 500 - 1000 W.
The further heightening of the beam current is
accompanied by the transformation of the oscillations into
those of the stochastic type (see Fig. 4 c). These problems
are in detail investigated in [6].
In Fig.5, it is demonstrated the oscillation spectrum in
the pulse regime, when the prolongation of the
accelerating voltage rising edge and the trailing edge of
the pulse substantially exceed the duration of the linear
stage in the oscillation establishment.
1 S(f)
0
0.4 0.8 1.2 f, GHz
Fig.5. The output signal microwave spectrum in the pulse
mode of operation
As this graph demonstrates, in the pulse mode of
operation one can obtain the oscillation integral spectrum
within the band 0.4-1.5 GHz.
CONCLUSIONS
The experimental excitation of the multi-frequency
oscillations in a vacuum helical slow-wave structure does
confirms the theory. It is demonstrated that the filling of a
transit channel with the plasma causes the starting current
decrease. In addition, the multi-frequency oscillation
spectrum is broadened and the signal amplitudes at
different frequencies are leveled.
REFERENCES
1. A.I. Grekov, V.V. Krutchkov, G.V. Ruvinskiy, V.S.
Tishina. Design and investigation of high-power helix
TWT for systems of distant and space communication //
Elektronika i radiofizika SVSh, St-Petersburg, 24-28 May,
1999, p.45-48. (In Russian).
2. N.S. Ginzburg, S.P. Kuznetsov, T.N. Fedoseeva The
theory of transient processes in relativistic BWO //Izv.
Vuzov. Radiofizika. 1978. v.21, 7, p. 1037-1052. (In
Russian).
3. B.P. Bezruchko, S.P. Kuznetsov, D.I. Trubetckov //
Nelinejnye volny. Stohastishnost’ i turbulentnost’. Gorkiy:
IPF AN SSSR, 1980, p. 29-33. (In Russian).
4. N.S. Ginzburg, N.I. Zaitcev, E.V. Iliakov, I.S. Kulagin.
Observation of auto drive conditions of oscillation in
powerful BWO // Pisma v ZhTF. 1998, v.24, 20.
p.66-71. (In Russian).
5. B.P. Bezrutshko, S.P. Kuznetsov. Experimental
investigation of nonlinear nonstationary processes in
BWO //Izv. Vuzov. Radiofizika. 1978. v.21. 7, p. 1053-
1059. (In Russian).
6. A.K. Berezin, Ya. Fainberg, A.M. Artamoshkin,
I.A. Beziazuchny, V.I. Kurilko, Y.M. Lyapkalo, V.S. Us
Plasma-beam generator of stochastic oscillations of a
decimeter wave band // Fizika plazmy. 1994. v.20, 9,
p. 782-789. (In Russian).
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