The dynamics of decay processes in rare plasma
The results of the experimental and theoretical investigations of chaotic decay process of HF wave on two new − HF and LF wave in the cylindrical resonator filled with rare plasma are presented. The branches of oscillations which can participate in such process are specified. The possible mechanis...
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| Zitieren: | The dynamics of decay processes in rare plasma / A.N. Antonov, V.A.Buts, I.K. Koval’chuk, O.F. Kovpik, E.A.Kornilov, V.G. Svichensky, D.V. Tarasov // Вопросы атомной науки и техники. — 2009. — № 1. — С. 104-106. — Бібліогр.: 4 назв. — англ. |
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irk-123456789-883092015-11-12T03:02:40Z The dynamics of decay processes in rare plasma Antonov, A.N. Buts, V.A. Koval’chuk, I.K. Kovpik, O.F. Kornilov, E.A. Svichensky, V.G. Tarasov, D.V. Плазменная электроника The results of the experimental and theoretical investigations of chaotic decay process of HF wave on two new − HF and LF wave in the cylindrical resonator filled with rare plasma are presented. The branches of oscillations which can participate in such process are specified. The possible mechanisms of appearance of burst of radiation which follows after certain time delay after the main impulse obtained in the experiment are discussed. The qualitative agreement of the theoretical deductions with the experimental results is observed. Представлен результати експериментального та теоретичного дослідження процесу хаотичного розпаду ВЧ- хвилі на дві нові – ВЧ та НЧ в циліндричному резонаторі, що заповнений рідкою плазмою. Вказані гілки коливань, які можуть брати участь в такому процесі. Обговорюються можливі механізми появи виявленого в експерименті сплеску випромінювання, що з’являється з деякою часовою затримкою після першого імпульсу. Відзначено якісний збіг теоретичних висновків з експериментальними результатами. Представлены результаты экспериментального и теоретического исследования процесса хаотического распада ВЧ- волны на две новые – ВЧ и НЧ в цилиндрическом резонаторе, заполненном редкой плазмой. Указаны ветви колебаний, которые могут участвовать в таком процессе. Обсуждаются возможные механизмы появления обнаруженного в эксперименте всплеска излучения, следующего с некоторой временной задержкой после основного импульса. Отмечено качественное согласие теоретических выводов с экспериментальными результатами. 2009 Article The dynamics of decay processes in rare plasma / A.N. Antonov, V.A.Buts, I.K. Koval’chuk, O.F. Kovpik, E.A.Kornilov, V.G. Svichensky, D.V. Tarasov // Вопросы атомной науки и техники. — 2009. — № 1. — С. 104-106. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS:52.40. Mj http://dspace.nbuv.gov.ua/handle/123456789/88309 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
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Плазменная электроника Плазменная электроника |
| spellingShingle |
Плазменная электроника Плазменная электроника Antonov, A.N. Buts, V.A. Koval’chuk, I.K. Kovpik, O.F. Kornilov, E.A. Svichensky, V.G. Tarasov, D.V. The dynamics of decay processes in rare plasma Вопросы атомной науки и техники |
| description |
The results of the experimental and theoretical investigations of chaotic decay process of HF wave on two new − HF
and LF wave in the cylindrical resonator filled with rare plasma are presented. The branches of oscillations which can
participate in such process are specified. The possible mechanisms of appearance of burst of radiation which follows
after certain time delay after the main impulse obtained in the experiment are discussed. The qualitative agreement of
the theoretical deductions with the experimental results is observed. |
| format |
Article |
| author |
Antonov, A.N. Buts, V.A. Koval’chuk, I.K. Kovpik, O.F. Kornilov, E.A. Svichensky, V.G. Tarasov, D.V. |
| author_facet |
Antonov, A.N. Buts, V.A. Koval’chuk, I.K. Kovpik, O.F. Kornilov, E.A. Svichensky, V.G. Tarasov, D.V. |
| author_sort |
Antonov, A.N. |
| title |
The dynamics of decay processes in rare plasma |
| title_short |
The dynamics of decay processes in rare plasma |
| title_full |
The dynamics of decay processes in rare plasma |
| title_fullStr |
The dynamics of decay processes in rare plasma |
| title_full_unstemmed |
The dynamics of decay processes in rare plasma |
| title_sort |
dynamics of decay processes in rare plasma |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2009 |
| topic_facet |
Плазменная электроника |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/88309 |
| citation_txt |
The dynamics of decay processes in rare plasma / A.N. Antonov, V.A.Buts, I.K. Koval’chuk, O.F. Kovpik, E.A.Kornilov, V.G. Svichensky,
D.V. Tarasov // Вопросы атомной науки и техники. — 2009. — № 1. — С. 104-106. — Бібліогр.: 4 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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| fulltext |
THE DYNAMICS OF DECAY PROCESSES IN RARE PLASMA
A.N. Antonov, V.A.Buts, I.K. Koval’chuk, O.F. Kovpik, E.A.Kornilov, V.G. Svichensky,
D.V. Tarasov
NSC “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine,
E-mail: vbuts@kipt.kharkov.ua
The results of the experimental and theoretical investigations of chaotic decay process of HF wave on two new − HF
and LF wave in the cylindrical resonator filled with rare plasma are presented. The branches of oscillations which can
participate in such process are specified. The possible mechanisms of appearance of burst of radiation which follows
after certain time delay after the main impulse obtained in the experiment are discussed. The qualitative agreement of
the theoretical deductions with the experimental results is observed.
PACS:52.40. Mj
1. INTRODUCTION
The decay processes of the regular waves in nonlinear
mediums are studied very well. The processes of
nonlinear waves interaction were also investigated in
details for the cases when the waves are completely
irregular and interaction occurs through intensities [1,2].
The case when the regular dynamics becomes chaotic is
not enough investigated. Such processes can play an
important role in plasma, especially in the beam-plasma
systems [3].
The modified decay of one HF waves on new high-
frequency and low-frequency can be one of the examples.
In [3,4] it was obtained the criterion which can led to chaos
in such system which, can be presented in the following
form / 1l fVA ω > where V - the matrix element of
nonlinear interaction, A - the amplitude of decaying wave,
lfω - the frequency of the low-frequency wave
participating in the decay process. In the present report the
results of the experimental and theoretical investigations of
such process are given. The dispersion properties of the
cylindrical wave guide partially filled with magnetoactive
plasma are explored, the numerical investigations of decay
process of HF wave on new HF and LF of a wave were
carried out, the cascades of decays are reviewed. The
process of transition to chaos in conditions of decay
instability was investigated experimentally.
2. BRIEF RESULTS OF THEORETICAL
INVESTIGATIONS
For realization the condition of transition to chaos it is
necessary that the investigated system had enough low
natural frequencies, as it is seen from stochasticity
criterion expression which is given above. With reference
to experiment it is necessary to specify, which waves can
participate in the decay process. Moreover, it is desirable
to use the system with rich dispersion when the distance
between natural frequencies is small.
In the experimental setup which will be described in
more detail below, the round cylindrical resonator partially
filled with magnetoactive plasma is used. The frequency of a
pumping wave is close to the electron cyclotron frequency.
In order to define frequencies which can participate in the
decay process, the simplified model was investigated.
The dispersion properties of the round cylindrical
waveguide filled by cylindrical plasma are theoretically
investigated. The axes of plasma and a wave guide
coincide. All the system is placed into longitudinal constant
homogeneous magnetic field. For the chosen model the
dispersion equation describing fast symmetric waves
analytically was obtained. It was analytically and
numerically investigated in details near to the upper hybrid
frequency. Thus it was supposed, that plasma is rare (the
plasma frequency is much less then pumping wave which
is in its turn close to electronic cyclotron frequency). The
results of investigations of dispersion properties of the
wave guide partially filled by plasma are given in Fig. 1.
Fast wavesSlow waves
ω p
Infinite number of solutions
ω = k
z
c
ω
κ z
ω h
ω p
Infinite number of solutions
Waveguide filled with plasma
ω p/ω h<<1; ω h~ ω
Upper hybrid
Waveguide dispersion
Waveguide dispersion
ω 2
h-ω 2
p
ω 2
h+ω 2
p
ω 2
e+ω 2
p
Fig.1. The dispersion of the metal wave guide filled by
plasma
Is of interest the field of frequencies laying below
upper hybrid frequency which is shown in Fig. 1. Here
there is a large number of branches which are located
almost parallelly to horizontal axis. The parallelogram in
the figure corresponds to those modes which can
participate in the decay.
The process of decay was investigated numerically.
The model equations were obtained. The left-hand part of
each of these equations corresponded to the linear
oscillator, and the right part described the nonlinear
interaction of such oscillators. At the performance of
stochasticity criterion the dynamics of decay was
irregular. It is confirmed with spectrums and correlation
functions of the obtained realizations. The spectra were
wide and the correlation functions quickly fell down. At
disturbance of the criteria of stochasticity appearance,
with decreasing of the initial amplitude of pumping wave,
the spectrums became more and more narrow and time of
correlation was increased.
104 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2009. № 1.
Series: Plasma Physics (15), p. 104-106.
The opportunity of realization of cascade processes
was investigated analytically and numerically. In this case
the wave excited during one decay HF enters another
dacay process in which it represents as a pumping wave.
The equations for amplitudes of the waves participating in
such process are obtained, their analytical analysis and
numerical examination is done. The obtained spectrums
and correlation functions indicate that in such scheme the
realization of chaotic regimes is possible.
3. THE EXPERIMENTAL RESULTS
The experimental setup is multimode resonator which
is placed into the longitudinal magnetic field. The length
of the resonator is 65 cm, radius is 7.5 cm. The value of
the applied magnetic field is 950 Gs . Plasma in the
resonator is created with electron bunch with energy
600 eV and the current 90 mА. The density of plasma in
the resonator is 910pn : cm-3, and its radius is 2: cm.
For excitation of the pumping wave in the resonator on
frequency 2.77 GHz the magnetron generator is used.
During carrying out of these experiments it was revealed,
that the impulse of excited microwave oscillations on
duration ( 2≈ µs) is much greater, than the pulse length
of the magnetron. After some micro seconds after its
ending the bursts of the microwave oscillations appear in
the resonator. The duration of these bursts, the time of
their delay concerning the main impulse, and also the
number of these bursts depend on conditions of the
experiment. Their recurrence has quasiperiodic character.
The amplitude of each of the following burst decreases
through attenuation. The characteristic form of
microwaves impulses excited in the resonator, and the
bursts accompanying them obtained with numeral
oscillograph are presented in Fig. 2. As it seen, during the
time interval between the main impulse and the burst in
the resonator, the electromagnetic field does not
disappear.
Occurrence of the bursts had random character on time
and on amplitude. At decreasing of the value of the
magnetic field on half of the length of the resonator on
25 %, the regularity of occurrence of recurring impulses
of the microwave radiation increased. Recurring impulses
of the microwave radiation are accompanied by
occurrence of luminescence pulses of the plasma and
pulses of the X-rays, caused by inhibiting of accelerated
electrons from tens to several hundreds kiloelectronvolts
on neutral atoms of remanent gas.
Occurrence of low-frequency oscillations in the
resonator is observed experimentally. It points out that
there is a nonlinear decay of the microwave oscillations
excited by an external source (magnetron) on two new
modes: high-frequency and low-frequency as it was
discussed in the previous section. In the experiment
conditions the electronic cyclotron frequency is close to
frequency of excitation, and the plasma frequency is
essentially less each of them. Experimental investigations
have shown that with increasing of the power injected
into the resonator, process of decay becomes chaotic.
With its increasing the dynamics of a low-frequency
mode becomes irregular. With magnification of injected
power the spectrum of low-frequency oscillations
becomes wide. Deductions of analytical and numerical
examinations which are stated in section 2 are
qualitatively well agreed with this experimental result. It
allows to confirm, that in the resonator the process of
stochastic decay is realized.
Fig.2. The oscillogram of high-frequency oscillations in
the resonator
It is necessary to note, that the spectrum of oscillations
which can participate in the decay, actually can be mush
richer than the one which was explored in section 2. It is
related the fact with that in the investigated experimental
system, there are asymmetrical modes which were not
took into account above.
The mechanism of occurrence of the bursts is not
studied up to now. It is possible to suggest two
explanations of their occurrence. On the one hand,
occurrence of these impulses can be caused by electron
cyclotron instability which develops after the ending of
the main impulse. The other possible reason of occurrence
of the bursts can be the nonlinear interaction of the waves
which leads to periodic returns (Fermi-Pasta-Ulam
problem).
For checking out of the first hypothesis the estimation
of the increment of electronic cyclotron instability which
is proportional to derivatives of distribution function of
electrons of plasma on traversal and longitudinal
velocities has been made. Generally the increments of
cyclotron instability appeared large enough. In order to
explain occurrence of the bursts as a result of
development of this instability it is necessary to guess,
that in the experiment formed the distribution function
with the strongly pronounced plateau. Realization of such
function in experiment is represented improbable.
In the second case the model of nonlinear string
considering quadratic nonlinearity is used. In numerical
calculations returns are observed, particularly in the case
when at the initial moment of time the first space
105
harmonic is excited in a string. The qualitative analysis of
return processes shows, that it is necessary to excite
several hundreds of natural modes of the resonator in
order to realize return processes.
Now there are no experimental information concerning
the view of distribution function of particles of plasma.
There is also no information about quantity of modes
which are excited in the resonator. For this reason we
cannot make the unequivocal choice between these two
possible mechanisms of bursts occurrence.
4. CONCLUSIONS
Experimentally was demonstrated the opportunity of
realization of chaos dynamics of modified decay of one
HF modes in plasmafiiled electrodynamical structure on
new modes, one of which remains high-frequency, and
second is low-frequency (plasma). The results of
numerical and theoretical investigations qualitatively
agree with experimental results. The obtained results can
be used for development of broadband noise generators.
However, in experiment new circumstances was
obtained – the occurrence of bursts of radiation, which
explanation needs additional investigations.
REFERENCES
1.B.B. Kadomtsev. Kollektivniye yavleniya v plazme. M.:
“Nauka”,1988 (In Russian).
2.H. Wilhelmsson, J.Weiland. Coherentnoye nelineynoye
vzaimodeystviye voln v plazme. M.: “Energoatomizdat”.
1983 (Russian transl.).
3.V.A. Buts, I.K. Koval’chuk, E.A. Kornilov,
D.V. Tarasov. Stabilization beam instability as a result
of development of local instability at interaction of type
a wave-wave // Physics of plasma. 2006, v. 32, N 6,
p. 1–10.
4.V.A. Buts, O.V. Manuylenko, K.N. Stepanov,
A.P. Tolstoluzhsky. Chaoticheskaya dynamika
zaryazhennikh chastits pri vzaimodeystvii tipa volna-
chastitsa i chaoticheskaya dynamika voln pri
slabonelineynom vzaimodeystvii tipa volna-volna //
Phizika plazmy. 1994, v. 20, N 9, p.794–801 (In
Russian).
Article received 22.09.08
ДИНАМИКА РАСПАДНЫХ ПРОЦЕССОВ В РЕДКОЙ ПЛАЗМЕ
А.Н. Антонов, В.А. Буц, И.К. Ковальчук, О.Ф. Ковпик, Е.А. Корнилов, В.Г. Свиченський, Д.В. Тарасов
Представлены результаты экспериментального и теоретического исследования процесса хаотического
распада ВЧ- волны на две новые – ВЧ и НЧ в цилиндрическом резонаторе, заполненном редкой плазмой.
Указаны ветви колебаний, которые могут участвовать в таком процессе. Обсуждаются возможные механизмы
появления обнаруженного в эксперименте всплеска излучения, следующего с некоторой временной задержкой
после основного импульса. Отмечено качественное согласие теоретических выводов с экспериментальными
результатами.
ДИНАМІКА РОЗПАДНИХ ПРОЦЕСІВ В РІДКИЙ ПЛАЗМІ
О.Н. Антонов, В.О. Буц, І.К. Ковальчук, О.Ф. Ковпік, Є.О. Корнілов, В.Г. Свіченський, Д.В. Тарасов
Представлен результати експериментального та теоретичного дослідження процесу хаотичного розпаду
ВЧ- хвилі на дві нові – ВЧ та НЧ в циліндричному резонаторі, що заповнений рідкою плазмою. Вказані гілки
коливань, які можуть брати участь в такому процесі. Обговорюються можливі механізми появи виявленого в
експерименті сплеску випромінювання, що з’являється з деякою часовою затримкою після першого імпульсу.
Відзначено якісний збіг теоретичних висновків з експериментальними результатами.
106
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