Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves

The dynamics of nonreciprocally coupled oscillators and coupled waves is studied. Such coupling can lead to converting the energy of low-frequency (LF) oscillations to the energy of high-frequency (HF) oscillations. The influence of the resonant properties of the coupling elements on the condition...

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spelling Buts, V.A.
Vavriv, D.M.
2019-02-14T18:40:59Z
2019-02-14T18:40:59Z
2018
Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves / V.A. Buts, D.M. Vavriv // Вопросы атомной науки и техники. — 2018. — № 4. — С. 213-216. — Бібліогр.: 5 назв. — англ.
1562-6016
PACS: 04.30.Nk; 52.35.Mw; 52.35.Mw; 78.70.Gq
https://nasplib.isofts.kiev.ua/handle/123456789/147438
The dynamics of nonreciprocally coupled oscillators and coupled waves is studied. Such coupling can lead to converting the energy of low-frequency (LF) oscillations to the energy of high-frequency (HF) oscillations. The influence of the resonant properties of the coupling elements on the conditions of the energy conversion is carried out. It is shown that this conversion can be realized when either the amplitude or the phase of the coupling coefficient is modulated at a low-frequency. By the example of waves in a rare magnetoactive plasma, it is shown for the first time that the discussed energy conversion takes also place in a system of interacting waves. Results of analytical and numerical studies illustrating the conditions for the excitation of high-frequency oscillations due to the energy conversion are presented.
Досліджено динаміку зв'язаних осциляторів і хвиль при наявності невзаємного зв'язку між ними, який призводить до можливості перетворення енергії низькочастотних коливань в енергію високочастотних коливань. Проведено аналіз впливу резонансних властивостей елементів зв'язку на умови перетворення енергії. Показано, що перетворення енергії можна реалізувати як при низькочастотній амплітудній, так і при низькочастотній фазовій модуляції коефіцієнта зв'язку. На прикладі аналізу поширення хвиль у рідкій магнітоактивній плазмі вперше показана можливість перетворення енергії і при взаємодії хвиль. Наведено результати аналітичного і чисельного дослідження, що ілюструють умови збудження високочастотних коливань і їх властивості.
Исследована динамика связанных осцилляторов и волн при наличии невзаимной связи между ними, которая приводит к возможности преобразования энергии низкочастотных колебаний в энергию высокочастотных колебаний. Проведен анализ влияния резонансных свойств элементов связи на условия преобразования энергии. Показано, что преобразование энергии можно реализовать как при низкочастотной амплитудной, так и при низкочастотной фазовой модуляции коэффициента связи. На примере анализа распространения волн в редкой магнитоактивной плазме впервые показана возможность преобразования энергии и при взаимодействии волн. Приведены результаты аналитического и численного исследований, иллюстрирующие условия возбуждения высокочастотных колебаний и их свойства.
en
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
Вопросы атомной науки и техники
Нелинейные процессы
Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves
Роль невзаємності в теорії пов'язаних коливань і пов'язаних хвиль
Роль невзаимности в теории связанных колебаний и связанных волн
Article
published earlier
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
title Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves
spellingShingle Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves
Buts, V.A.
Vavriv, D.M.
Нелинейные процессы
title_short Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves
title_full Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves
title_fullStr Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves
title_full_unstemmed Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves
title_sort тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves
author Buts, V.A.
Vavriv, D.M.
author_facet Buts, V.A.
Vavriv, D.M.
topic Нелинейные процессы
topic_facet Нелинейные процессы
publishDate 2018
language English
container_title Вопросы атомной науки и техники
publisher Національний науковий центр «Харківський фізико-технічний інститут» НАН України
format Article
title_alt Роль невзаємності в теорії пов'язаних коливань і пов'язаних хвиль
Роль невзаимности в теории связанных колебаний и связанных волн
description The dynamics of nonreciprocally coupled oscillators and coupled waves is studied. Such coupling can lead to converting the energy of low-frequency (LF) oscillations to the energy of high-frequency (HF) oscillations. The influence of the resonant properties of the coupling elements on the conditions of the energy conversion is carried out. It is shown that this conversion can be realized when either the amplitude or the phase of the coupling coefficient is modulated at a low-frequency. By the example of waves in a rare magnetoactive plasma, it is shown for the first time that the discussed energy conversion takes also place in a system of interacting waves. Results of analytical and numerical studies illustrating the conditions for the excitation of high-frequency oscillations due to the energy conversion are presented. Досліджено динаміку зв'язаних осциляторів і хвиль при наявності невзаємного зв'язку між ними, який призводить до можливості перетворення енергії низькочастотних коливань в енергію високочастотних коливань. Проведено аналіз впливу резонансних властивостей елементів зв'язку на умови перетворення енергії. Показано, що перетворення енергії можна реалізувати як при низькочастотній амплітудній, так і при низькочастотній фазовій модуляції коефіцієнта зв'язку. На прикладі аналізу поширення хвиль у рідкій магнітоактивній плазмі вперше показана можливість перетворення енергії і при взаємодії хвиль. Наведено результати аналітичного і чисельного дослідження, що ілюструють умови збудження високочастотних коливань і їх властивості. Исследована динамика связанных осцилляторов и волн при наличии невзаимной связи между ними, которая приводит к возможности преобразования энергии низкочастотных колебаний в энергию высокочастотных колебаний. Проведен анализ влияния резонансных свойств элементов связи на условия преобразования энергии. Показано, что преобразование энергии можно реализовать как при низкочастотной амплитудной, так и при низкочастотной фазовой модуляции коэффициента связи. На примере анализа распространения волн в редкой магнитоактивной плазме впервые показана возможность преобразования энергии и при взаимодействии волн. Приведены результаты аналитического и численного исследований, иллюстрирующие условия возбуждения высокочастотных колебаний и их свойства.
issn 1562-6016
url https://nasplib.isofts.kiev.ua/handle/123456789/147438
citation_txt Тhe effect of nonreciprocity on the dynamics of coupled oscillators and coupled waves / V.A. Buts, D.M. Vavriv // Вопросы атомной науки и техники. — 2018. — № 4. — С. 213-216. — Бібліогр.: 5 назв. — англ.
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fulltext ISSN 1562-6016. ВАНТ. 2018. №4(116) 213 THE EFFECT OF NONRECIPROCITY ON THE DYNAMICS OF COUPLED OSCILLATORS AND COUPLED WAVES V.A. Buts1,2, D.M. Vavriv3 1National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine; 2V.N. Karazin Kharkov National University, Kharkov, Ukraine; 3Institute of Radio Astronomy of NAS of Ukraine, Kharkov, Ukraine E-mail: vbuts@kipt.kharkov.ua; vavriv@rian.kharkov.ua The dynamics of nonreciprocally coupled oscillators and coupled waves is studied. Such coupling can lead to converting the energy of low-frequency (LF) oscillations to the energy of high-frequency (HF) oscillations. The influence of the resonant properties of the coupling elements on the conditions of the energy conversion is carried out. It is shown that this conversion can be realized when either the amplitude or the phase of the coupling coeffi- cient is modulated at a low-frequency. By the example of waves in a rare magnetoactive plasma, it is shown for the first time that the discussed energy conversion takes also place in a system of interacting waves. Results of analyti- cal and numerical studies illustrating the conditions for the excitation of high-frequency oscillations due to the ener- gy conversion are presented. PACS: 04.30.Nk; 52.35.Mw; 52.35.Mw; 78.70.Gq INTRODUCTION In the papers [1, 2], it was described that the intro- duction of a non-reciprocal coupling between oscillating systems opens a possibility of the energy converting from low-frequency (LF) oscillations to high-frequency (HF) oscillations. It was also noted that the most inter- esting direction of using the discovered mechanism of the energy conversion is related with the development of novel types of sources of electromagnetic radiation, including sources of terahertz radiation. It should be noted that in this frequency range, the coupling ele- ments themselves have usually resonant properties. However, in [1, 2] these elements were considered as frequency-independent elements. Therefore, it seems important to investigate the influence of resonant prop- erties of the coupling elements on the dynamics of cou- pled oscillators. The corresponding analysis is presented in the next section, where each of the coupling elements is also considered as a separate oscillator coupled with other oscillators. So far, the case was considered [1, 2] when the non- reciprocity of the coupling and the LF modulation of the coupling coefficient were provided by introducing an amplitude modulation of the coupling coefficients. It should be borne in mind that the amplitude modulation is not always practical, therefore, we also consider in this paper a possibility of applying a LF phase modula- tion to realize the conversion of LF oscillations into HF ones. The results of this study are presented in the third section of the paper. In our previous works [1, 2], we considered systems where HF oscillations are excited as a result of three- frequency interaction under the following resonance conditions 1 2 ,n nω ω ω− = ± where 1nω and 2nω are normal frequencies of a system of two coupled oscillators, ω is the frequency of LF modulation, which is much smaller than 1nω , 2nω . The case was mainly considered when the partial frequen- cies 1pω , 2pω of the oscillators are equal. In the fourth section of this paper it is shown that, with an appropri- ate choice of the coupling between the oscillators, the excitation of HF oscillations is possible even if the following condition is satisfied 1 2p pω ω ω− = ± that is, with unequal partial frequencies of the interact- ing oscillators. In the fifth section, it is shown that the mechanism of the energy conversion found in a system of interact- ing oscillators can be also realized when waves interact. This result is demonstrated by analyzing the propaga- tion of two high-frequency transverse electromagnetic waves in a rare magnetoactive plasma. The last section summarizes the results presented in the paper. 1. INFLUENCE OF RESONANT PROPERTIES OF COUPLING ELEMENTS As mentioned above, at high frequencies coupling elements can have resonant properties and should also be regarded as oscillatory systems. In this case, the simplest model of coupled oscillators can be represent- ed as a ring of four oscillators, as shown in Fig. 1. Fig. 1. Scheme of the oscillatory system. Arrows indicate the direction of connection Numbers 1 and 3 show high-frequency oscillation systems (resonators). The natural frequencies of these resonators are equal to 0ω . Numbers 2 and 4 denote nonreciprocal coupling elements. The eigenfrequencies of these elements coincide and are equal to 1ω . Arrows indicate the direction of the wave propagation in this ring. A set of equations that describes the dynamics of such a system can be represented in the form: mailto:vbuts@kipt.kharkov.ua ISSN 1562-6016. ВАНТ. 2018. №4(116) 214 2 1 0 1 4x x xω µ+ = ; 2 2 1 2 1x x xω µ+ = ; (1) 2 3 0 3 2x x xω µ+ = ; 2 4 1 4 3x x xω µ+ = . It is easy to determine that this oscillatory system has the following normal frequencies: ( )2 2 2 0 0 1 0/ 2N ω µ ω ω ωΩ = ± − . Assuming that the coupling coefficients are small ( 2 0,1µ ω<< ), from (1), one can find the following aver- aged equations for determining the complex amplitudes of the coupled oscillators: 1 4 02 a a i µ ω = ; 2 1 12 a a i µ ω = ; (2) 3 2 02 a a i µ ω = ; 4 3 1 . 2 a a i µ ω = Note that this set of equations is not changed if some coupling coefficients are slow varying functions of time. Let, for example, the coupling coefficients in the third and fourth equations of (2) are such functions of time 1( )tµ µ= . Then from (2), we find the following equation describing the dynamics of the amplitudes of the first and third oscillators (resonators): [ ] [ ] 2 2 1 3 1 32 0d a a a a dt + +Ω + = , (3) where ( )22 1 0 1(t) / 4µ ω ωΩ = . Let us assume that the function ( )21(t)µ has the fol- lowing form ( ) ( )( )2 4 1 2(t) 1 cos 2µ ω ε t= + , where 2 2 0 1/ 2tt ω ω ω= ⋅ and 2 2 0 1ω ω ω<< . Then (3) can be reduced to Mathieu equation: [ ] ( )[ ] 2 1 3 1 32 1 cos2 0d a a a a d ε t t + + + + = . (4) From this equation, it follows that the presence of the resonant properties of the coupling elements does not prevent the energy transformation from LF oscilla- tions into the energy of HF oscillations. One should only take into account that the eigenfrequencies of the coupling elements are essential parameters of the entire oscillatory system, and their parameters should be ap- propriately selected for the realization of the considered energy transformation. 2. MODULATION OF THE PHASE OF THE COUPLING COEFFICIENTS In the papers [1, 2], an amplitude modulation of the coupling coefficients was considered. For a number of practical applications, it is more convenient to use a phase modulation of the coupling coefficient. To de- scribe the dynamics of a system of two coupled identi- cal oscillators, in which the phase of the coupling ele- ments is a function of time, we use the following system of equations: [ ]1 1 2( ) exp( ( )x x t i t xµ ϕ+ = ; 2 2 0 1x x xµ+ = . (5) Here ( ) ( )t and tµ ϕ are real slow varying func- tions of time. We look for a solution of (5) in the fol- lowing form: ( ) ( )1 1 2exp expx A it A it= ⋅ + ⋅ −   ( ) ( )2 1 2exp expx B it B it= ⋅ + ⋅ −   . (6) Here the amplitudes kA and kB (k=1, 2) are slow varying functions of time. Applying the averaging tech- nique to (6), we obtain to the following set of equations: [ ]1 1( ) exp( ( )iA t i t Bµ ϕ= , 1 0 1iB Aµ= , (7) [ ]2 2( ) exp( ( )iA t i t Bµ ϕ− = , 2 0 2.iB Aµ− = Here the amplitudes kA and kB are complex func- tions: k k kA A iA′ ′′= + ; k k kB B iB′ ′′= + . To find the real and imaginary components, we come to the following sys- tem of equations: [ ] [ ]1 0 1 0 1( )cos ( )sinB t B t Bµ µ ϕ µ µ ϕ′ ′ ′′+ = , [ ] [ ]1 0 1 0 1( )cos ( )sinB t B t Bµ µ ϕ µ µ ϕ′′ ′′ ′+ = − . (8) An analogous system can also be obtained for the function k k kA A iA′ ′′= + . The sets of equations (5) and (8) were solved numerically. In Fig. 2 typical build-up of the amplitude of high-frequency oscillations is shown. This example illustrate that the energy conver- sion can be also realized when the phase of the coupling coefficient is modulated at a low-frequency. Fig. 2. The characteristic dependence of the amplitudes of the oscillators on time ( )0nT tµ µ≡ ⋅ at sinϕ t= ; 1(0) 1x = 3. EXCITATION OF HF OSCILLATIONS WHEN THE PARTIAL FREQUENCIES DO NOT COINCIDE In the works [1, 2], the partial frequencies of the in- teracting oscillators were considered to be equal. Under this condition, a three-frequency interaction and the excitation of HF oscillations were realized when the difference of the normal frequencies was approximately equal to the frequency of the LF modulation. In this section, we show that with a certain method of oscillators coupling, HF oscillations are excited also when the partial frequencies do not coincide. This case is realized in the absence of constant in time coupling between the oscillators. However, a nonreciprocity of the coupling, as in the previous case, is needed. A set of equations that describes such a coupled oscillatory sys- tem can be represented as: ISSN 1562-6016. ВАНТ. 2018. №4(116) 215 ( )2 1 1 1 2 cosq q q tω µ ω+ ⋅ = ⋅ ( )2 2 2 2 1 cosq q q tω µ ω+ ⋅ = − ⋅ . (9) Here 2 1ω ω ω= − is the low frequency modulation of the coupling between the high-frequency oscillators. We look for the solution of (9) in the form: ( ) exp( ) ( ) exp( ).k k k k kq A t i t B t i tω ω= + − To find equations for slowly varying amplitudes, we at first come from (9) to the following system of equa- tions: [ ] 1 1 1 1 2 2 2 2 1 ( )exp( ) ( )exp( ) exp( ) exp( ) cos( ) 2 A t i t B t i t A i t B i t t i ω ω µ ω ω ω ω  − − =  = + −   [ ] 2 2 2 2 1 1 1 1 2 ( ) exp( ) ( ) exp( ) exp( ) exp( ) cos( ). 2 A t i t B t i t A i t B i t t i ω ω µ ω ω ω ω  − − =  = − + −   (10) From this equations, it is easy to determine the fol- lowing relations between the complex amplitudes 1 2 14 A A i µ ω = ; 2 1 24 A A i µ ω = − ; (11) 2 1 1 1 2 0 16 A Aµ ω ω − = . From (11), it immediately follows that the excitation of high-frequency oscillations can also occur in such a system as illustrated in Fig. 3. This figure shows the solution of the system of equations (9) at such parame- ters: 0.2µ = ; 0.01ω = ; 1 1ω = ; 2 1.01ω = ; 1(0) 0.1q = . Fig. 3. The excitation of oscillations of two coupled, different high-frequency oscillators (see system (9)). nT t≡ Fig. 4. Dispersion diagram of the waves participating in the interaction 4. THE ROLE OF NONRECIPROCITY IN THE DYNAMICS OF COUPLED WAVES In the above sections, we discussed the existence in coupled oscillators of LF- to HF energy transfer channel. It can be expected that a similar channel can exist in systems with interacting waves. Below, considering an example of coupling of transverse high-frequency waves to plasma waves, it is shown that such a channel does exist. However, as before, it exists only in the presence of a non-reciprocal coupling between interacting waves. We consider the following problem. Suppose that there are two high-frequency transverse electromagnetic waves that propagate through rare magnetoactive plas- ma ( ( )22 2~p Hω ω ω<< ). The frequencies of these waves are large, and the difference of these frequencies is close to the plasma frequency ( 2 1 pω ω ω− ≈ ). For sim- plicity, we consider a one-dimensional motion, i.e. all waves propagate and interact with each other only along the axis z and in time. A diagram of a possible interac- tion of the waves is shown in Fig. 4. It can be seen from diagram 4 that a three-wave interaction occurs. In this interaction, two transverse high-frequency waves and a plasma wave are involved. The structure of these waves and their dispersion characteristics are well known (see, for example, [4, 5]). The plasma wave is longitudinal with a large amplitude. We assume that this wave is given. In this case, the plasma frequency can be repre- sented only by its wave characteristic: ( )24 / . .p pe n m exp i z i t k cω p k ω = − +  (12) The equation for the electrical component of the field of the transverse electromagnetic waves can be obtained from the Maxwell equations: 2 2 2 1 (D) 0E c t ∂ D − = ∂   . (13) Here, ˆD Eε=   and ε̂ is the plasma permittivity tensor. We look for the components of the electric field of transverse waves in the form , 2,1 2,1 2,1( , ) ( ) . .x yE z t A t exp ik z i t k cω = − +  (14) Then it is convenient to represent equation (13) in the form of the following set of equations with respect to the amplitudes 1,2A : 2 2 22 2 2 1 12 A A i A t ω ε ω+ ∂ + = − ∂ ; 2 2 21 1 1 2 22 A A i A t ω ε ω− ∂ + = ∂ . (14) Here ( )2 2 2/H p Hε ω ω ω ω ω± ± ±= − are off-diagonal components of the permittivity tensor; 2 2 2 2 2 2 2 2 1 1/ , / .k c k cω ω= = The upper sign in these expressions corresponds to a wave propagating along the magnetic field 2ω ω+ = ; the lower sign belongs to a wave propagating in the oppo- site direction 1ω ω− = . When obtaining (14), the condi- tion of spatial synchronism 2 1k kk = + has been used. We note that the first wave 1 1, kω propagates in the direction opposite to the direction of the external mag- netic field. ISSN 1562-6016. ВАНТ. 2018. №4(116) 216 For an effective interaction of the waves, it is neces- sary that together with the spatial synchronism condition, the time synchronism should be satisfied: 2 1 0pω ω ω− − = . We look for a solution of (14) in the form 2,1 1,2 2,1( ) . .A a exp i t k cω= − + (15) Substituting (15) into (14), we obtain the following equations with respect to the slowly varying amplitudes 2,1a : 2 2,1 1 2 2,12 0 4 a a t ε ε ω ω+ −∂ − = ∂ . (16) It can be seen from this equation that the amplitudes of the transverse waves increase exponentially with the increment: ( )2 2 2/ 2H p Hω ω ω ωΓ ≈ − . (17) In this expression, it is taken into account that the frequencies of the HF waves are close to each other 2 1 1pω ω ω ω− = << . High-frequency transverse elec- tromagnetic waves receive energy from the LF Lang- muir waves excited in the plasma. CONCLUSIONS We note the most important results presented in the paper. There are two basic scientific results. The first is that the conversion of the energy of LF oscillations to the energy of HF frequency oscillations is a rather "strong" effect, in the sense that it can be realized in very different ways (see Sections 3 and 4), and also in the presence of significant perturbations, like, for ex- ample, additional resonances in the system (section 2). The second result is that the availability of nonreci- procity can create a channel for converting the energy of LF oscillations to HF oscillations not only in systems with coupled oscillators, but also in systems with cou- pled waves (see Section 5). In latter case, the presence of a nonreciprocity leads to a qualitatively new dynam- ics of the three-wave interaction. Indeed, it is well known (see, for example, [4 - 5]) that if at the initial instant of time the low-frequency wave has the largest amplitude in a system with a three-wave interaction, then practically no dynamics with energy exchange can occur in such system. In the case considered above, the presence of a nonreciprocity leads to the excitation of HF waves, in spite of the fact that at the initial moment only a low-frequency Langmuir wave exists. In our paper, there are also several results of practi- cal importance. At first, it is shown that when consider- ing the excitation of high-frequency oscillations (for example, in terahertz frequency range), it is necessary to take into account the oscillatory properties of the cou- pling elements (see Section 1). Secondly, it is proved that a phase modulation of the coupling coefficient can be used as well as an amplitude modulation to realize the energy transfer. At third, it is shown that oscillatory systems with different partial frequencies can be used for the conversion of LF- to HF oscillations. The only requirement in this case is that the modulation frequen- cy of the coupling coefficients of these systems should be approximately equal to the difference between the partial frequencies. REFERENCES 1. V.A. Buts, D.M. Vavriv, O.G. Nechayev, D.V. Tarasov. A Simple Method for Generating Electromagnetic Oscillations // IEEE Transactions on circuits and systems II. Express Briefs. 2015, v. 62, № 1, p. 36-40. 2. V.A. Buts, D.M. Vavriv. Role of Non-Reciprocity in the Theory of Oscillations // Radio Physics and Ra- dio Astronomy. 2018, v. 23, № 1, p. 60-71. 3. A.I. Akhiezer, I.A. Akhiezer, et al. Plasma Electro- dynamics. M.: “Nauka”. 1974, 719 p. (in Russian). 4. B.B. Kadomtsev. Collective Phenomena in Plasma. M.: “Nauka”. 1976, 238 p. (in Russian). 5. H.A. Wilhelmsson, J. Weiland. Coherent Non- Linear Interaction of Waves in Plasmas. M.: “Ener- goizdat”, 1981, 224 p. (in Russian). Article received 29.05.2018 РОЛЬ НЕВЗАИМНОСТИ В ТЕОРИИ СВЯЗАННЫХ КОЛЕБАНИЙ И СВЯЗАННЫХ ВОЛН В.А. Буц, Д.М. Ваврив Исследована динамика связанных осцилляторов и волн при наличии невзаимной связи между ними, ко- торая приводит к возможности преобразования энергии низкочастотных колебаний в энергию высокоча- стотных колебаний. Проведен анализ влияния резонансных свойств элементов связи на условия преобразо- вания энергии. Показано, что преобразование энергии можно реализовать как при низкочастотной ампли- тудной, так и при низкочастотной фазовой модуляции коэффициента связи. На примере анализа распро- странения волн в редкой магнитоактивной плазме впервые показана возможность преобразования энергии и при взаимодействии волн. Приведены результаты аналитического и численного исследований, иллюстри- рующие условия возбуждения высокочастотных колебаний и их свойства. РОЛЬ НЕВЗАЄМНОСТІ В ТЕОРІЇ ПОВ'ЯЗАНИХ КОЛИВАНЬ І ПОВ'ЯЗАНИХ ХВИЛЬ В.О. Буц, Д.М. Ваврів Досліджено динаміку зв'язаних осциляторів і хвиль при наявності невзаємного зв'язку між ними, який призводить до можливості перетворення енергії низькочастотних коливань в енергію високочастотних ко- ливань. Проведено аналіз впливу резонансних властивостей елементів зв'язку на умови перетворення енер- гії. Показано, що перетворення енергії можна реалізувати як при низькочастотній амплітудній, так і при низькочастотній фазовій модуляції коефіцієнта зв'язку. На прикладі аналізу поширення хвиль у рідкій маг- нітоактивній плазмі вперше показана можливість перетворення енергії і при взаємодії хвиль. Наведено ре- зультати аналітичного і чисельного дослідження, що ілюструють умови збудження високочастотних коли- вань і їх властивості. http://radar.kharkov.com/index.php?s=4&authorID=234 http://radar.kharkov.com/index.php?s=4&authorID=1 http://radar.kharkov.com/index.php?s=4&id=567 http://radar.kharkov.com/index.php?s=4&id=567