595 research outputs found
Complex plasmas: Interaction potentials and non-Hamiltonian dynamics
No full textThis thesis is a cumulative dissertation that consists of three papers.
The first paper addresses the issue of screening of a charged dust particle suspended in the plasma-wall transition layer of a plasma discharge. This problem is one of the fundamental issues in the physics of complex (dusty) plasmas, because the screening of charged dust particles determines the interaction forces between them and thus governs their dynamics. The kinetic model proposed in this paper considers a point charge embedded in a weakly-ionized plasma with ion drift. The latter is considered to be due to an external electric field and assumed to be mobility-limited. Here, "mobility-limited" means that the acceleration of ions in the external field is balanced by collisions of ions with neutrals and that this balance determines the drift velocity. The embedded point charge (i.e., a charged dust particle) perturbs the ion drift, and the resulting potential distribution around the dust particle is calculated. The results are proven to be in agreement with existing measurements performed in the plasma-wall transition layer of a rf plasma discharge. One of the important applications of this work is related to the possibility of tuning the pair interaction potential between dust particles by applying an external oscillating electric field. In particular, such a tuning allows studying electrorheological properties of strongly coupled systems on all relevant time scales. First experiments of this kind have already been performed onboard the International Space Station.
The second paper deals with the dust-lattice waves - oscillations of charged dust particles forming a crystalline structure in a plasma. The role of anisotropic screening of dust particles and variations of their charges is investigated. It is well known that the mentioned effects lead to non-Hamiltonian dynamics of dust particles and, as a result, can trigger an instability of the dust-lattice waves. This instability has been already observed in experiments. The new result is that the mutual influence of particles on their charges, not considered in the analysis of the dust-lattice waves before, is shown to be capable of making a significant contribution to this instability.
The third paper examines whether a similar instability can be observed in a cluster formed by two or three charged dust particles. It is found that an instability due to the non-Hamiltonian dynamics is only possible when the interparticle separation in the cluster is such that certain cluster eigenfrequencies are sufficiently close to each other.Настоящая диссертация является кумулятивной диссертацией и состоит из трех работ.
Первая работа посвящена экранированию заряженной пылевой частицы, левитируемой в приэлектродном слое плазменного разряда. Эта задача является одной из фундаментальных проблем физики пылевой плазмы, так как экранирование заряженных пылевых частиц определяет силы взаимодействия между ними и поэтому определяет их динамику. В статье предложена кинетическая модель, в которой рассматривается точечный заряд, помещенный в слабоионизированную плазму с ионным дрейфом. Предполагается, что ионный дрейф вызван внешним электрическим полем и соответствует мобильности ионов. Последнее означает, что подразумевается баланс между ускорением ионов во внешнем электрическом поле и столкновениями ионов с нейтралами, который и определяет скорость дрейфа. Внесенный точечный заряд (т.е., заряженная пылевая частица) возмущает дрейф ионов, и образующееся распределение потенциала вокруг пылевой частицы вычислено в настоящей работе. Результаты находятся в согласии с ранее опубликованными результатами измерений, выполненными в приэлектродном слое радиочастотного плазменного разряда. Одно из важных приложений этой работы связано с возможностью регулирования потенциала парного взаимодействия пылевых частиц посредством приложения внешнего осциллирующего электрического поля. В частности, такое регулирование позволяет изучать электрореологические свойства систем, в которых потенциальная энергия парного взаимодействия частиц превышает их кинетическую энергию. Первые эксперименты такого типа уже были проведены на борту Международной Космической Станции.
Предметом исследования второй работы являются так называемые пылекристаллические волны - колебания заряженных пылевых частиц, образующих кристаллическую структуру в плазме. Исследована роль как анизотропии экранирования пылевых частиц, так и вариаций их зарядов. Как известно, эти эффекты приводят к негамильтоновой динамике пылевых частиц и поэтому могут вызвать неустойчивость пылекристаллических волн, которая уже была обнаружена в экспериментах. Новый результат заключается в том, что взаимное влияние пылевых частиц на их заряды, которое ранее не учитывалось при анализе пылекристаллических волн, может обеспечить значительный вклад в эту неустойчивость.
В третьей работе исследовано, может ли подобная неустойчивость наблюдаться в кластере, состоящем из двух или трех пылевых частиц. Получено, что подобная неустойчивость из-за негамильтоновой динамики может возникнуть только тогда, когда расстояние между пылевыми частицами близко к резонансному значению, при котором определенные собственные частоты кластера совпадают.Diese Dissertation ist eine kumulative Dissertation und besteht aus drei Arbeiten.
Die erste Arbeit beschäftigt sich mit der Abschirmung des in einer Plasmarandschicht zur Schwebe gebrachten geladenen Staubteilchens. Dieses Problem ist von fundamentaler Bedeutung für die Physik der komplexen (staubigen) Plasmen, weil die Abschirmung die Form der Wechselwirkungen und somit die Dynamik der geladenen Staubteilchen bestimmt. In der Arbeit wird ein kinetisches Modell vorgeschlagen, in welchem ein Staubteilchen als eine Punktladung betrachtet wird, die sich in einem schwach ionisierten Plasma mit einer Ionendrift befindet. Es wird angenommen, dass die Ionendrift durch ein externes elektrisches Feld verursacht wird und dass diese Ionendrift der Mobilität der Ionen entspricht. Dies bedeutet, dass die Beschleunigung der Ionen im externen elektrischen Feld durch Ionen-Neutralteilchen-Stöße ausgeglichen wird und dass diese Kompensation die Geschwindigkeit der Ionendrift bestimmt. Die Punktladung (d.h. das Staubteilchen) stört diese Ionendrift, und in der vorliegenden Arbeit wird die resultierende Potentialverteilung des Staubteilchens im Plasma berechnet. Zudem wird festgestellt, dass die Resultate mit den früher in RF-Entladungen durchgeführten Experimenten konsistent sind. Die übergreifende Bedeutung dieser Untersuchung liegt in der Möglichkeit, damit durch ein externes elektrisches Wechselfeld das binäre Wechselwirkungspotential der Staubteilchen von außen zu steuern und somit z.B. elektrorheologische Eigenschaften von stark wechselwirkenden Systemen von Partikeln sichtbar zu machen und dynamisch auf allen relevanten Zeitskalen zu untersuchen. Erste Messungen dieser Art sind in Experimenten auf der Internationalen Raumstation bereits erfolgreich durchgeführt worden.
Die zweite Arbeit beschäftigt sich mit den sogenannten Staub-Gitter-Wellen (dust-lattice waves). Das sind Wellen, die durch Schwankungen der geladenen Staubteilchen, die eine Kristallstruktur im Plasma bilden, entstehen. In der vorliegenden Arbeit wird die Rolle sowohl der Anisotropie der Abschirmung der Staubteilchen als auch der Variation ihrer Ladungen untersucht. Wie bekannt führen diese Effekte zu nicht-Hamiltonischer Dynamik der Staubteilchen und können daher eine Instabilität der Staub-Gitter-Wellen auslösen. Solche Effekte sind in Experimenten bereits beobachtet worden. Das neue Ergebnis besteht darin, dass der gegenseitige Einfluss der Staubteilchen auf ihre Ladungen, ein Effekt, welcher bisher bei der Analyse der Staub-Gitter-Wellen noch nicht berücksichtigt wurde, einen wichtigen Beitrag zu dieser Instabilität leisten kann.
In der dritten Arbeit wird untersucht, ob eine ähnliche Instabilität in Partikelclustern, welche nur aus zwei oder drei Staubteilchen bestehen, beobachtet werden kann. Es wurde festgestellt, dass eine ähnliche Instabilität, die durch nicht-Hamiltonische Dynamik verursacht ist, nur dann möglich ist, wenn der Teilchenabstand so gewählt wird, dass bestimmte Eigenfrequenzen des Clusters gut miteinander übereinstimmen
«Elements of physiological hvdrobiology» by V. S. Ivlev is twenty five
No full textThe fundamental work by Ivlev V. S. written shortly before his death is considered in the aspect of its significance for development of modern hydrobiology and ecological physiology of hydrobionts. In this work V. S. Ivlev stands for the importance of physiological approaches in hydrobiology, study of mechanisms and peculiarities of adaptations of water animals to habitat conditions, production studies of populations. V. S. Ivlev's work, being a peculiar „physiological manifesto" in hydrobiology, has played a significant role in development of up-to-date methodology of hydrobiologjcal, studies in the country on the whole and at the Institute of Biology of Southern Seas of the Ukr. SSR Academy of Sciences in particular.Рассматривается значение фундаментальной работы В. С. Ивлева, написанной
незадолго до его смерти, для развития современной гидробиологии и экологической физиологии гидробионтов. В. С. Ивлев в указанной работе пропагандирует важность физиологических подходов в гидробиологии, изучения механизмов и особенностей адаптации водных животных к условиям обитания, продукционных исследований популяций. Работа В. С. Ивлева, представляющая собой своеобразный «физиологический манифест» в гидробиологии, сыграла значительную роль в становлении современной методологии гидробиологических исследований в стране в целом, в том числе и в Институте биологии южных морей АН Украины
Professor Dyuis D. Ivlev. Dedication to 85th Birtday
No full textDyuis D. Ivlev (1930-2013) is an outstanding scientist in the fields of Continuum Mechanics (theory of Perfect Plasticity and Fracture) and AppliedMathematics. He has much contributed to the mathematical theory of plasticity, especially to study of hyperbolic three-dimensional problems of theperfect plasticity. Dyuis D. Ivlev was born in Chuvashia Republick, Russia, on September 6, 1930. In 1948 he left Chuvashia and after passing examinations entered Moscow State University. He is a Mechanical Engineering graduate(1953) of Moscow State University. In 1953 he continued his research workas a post graduate student of the same university. In 1956 he received PhDin Solid Mechanics from Moscow State University. The title of his PhD dissertation work is Approximate Solution of Elasti-Plastic Problems by thesmall parameter method. Three years later he was awarded DSc (Phys. &Math.) Degree from Moscow State University for his dissertation study Three-Dimensional Problem of the Theory of Perfect Plasticity. Since 1959he has been working as head of the Department of Elasticity and Plasticityof Voronezh State University, then (1966-1970) as Prof. of Bauman StateTechnical University and (1971-1982) as head of the Department of Higher Mathematics of Russian Polytechnical University. In 1982 he returned toChuvashia working in Chuvash State University (until 1993) and ChuvashState Pedagogical University (1993-2013) as head of Department of Mathematical Analysis. Prof. Dyuis D. Ivlev has been a member of National Committee on Theoretical and Applied Mechanics, Scientific Council on Problems of SolidMechanics, Mathematics and Mechanics Expert Council of the Higher Attestation Committee. He is the author of several books on theory of perfectplasticity and its applications and nearly 250 papers on the subject
Doklady Physics V. 48, I. 08
No full textDoklady Physics -- August 2003
Volume 48, Issue 8, pp. 389-461
PHYSICS
Systematic Distortions of Signal Propagation Times in Random Inhomogeneous Media
O. A. Godin
pp. 389-393 Full Text: PDF (62 kB)
Atomistic Simulation of the Properties and Phase Transformations of FeO Wustite under High Pressures
I. Yu. Kantor and V. S. Urusov
pp. 394-397 Full Text: PDF (57 kB)
Possibility of Intensifying Chain Reactions in Combustible Mixtures by Laser Radiation Exciting Electronic States of O2 Molecules
A. M. Starik and N. S. Titova
pp. 398-404 Full Text: PDF (113 kB)
On the Phenomenological Description of Crystallization in Melts
S. O. Gladkov
pp. 405-408 Full Text: PDF (58 kB)
Landau–Lifshitz Equations for Magnetic Systems with Constant and Variable Memory
Ya. L. Kobelev, L. Ya. Kobelev, and E. P. Romanov
pp. 409-413 Full Text: PDF (57 kB)
Guided Modes in Photonic Crystal Fibers
V. I. Krivenkov
pp. 414-417 Full Text: PDF (50 kB)
Effect of the High Rate of Avalanche Ionization behind a Shock Wave in a Monatomic Gas
V. M. Fomin, B. V. Postnikov, and V. I. Yakovlev
pp. 418-421 Full Text: PDF (60 kB)
On the Diffraction of Waves by an Apodized Periodic Structure
V. F. Kravchenko and V. I. Pustovoit
pp. 422-426 Full Text: PDF (105 kB)
TECHNICAL PHYSICS
Universal Asymptotic Behavior of the Power Spectrum of (1/(f)) Noise
A. G. Budarin
pp. 427-431 Full Text: PDF (69 kB)
Suppression of the Residual Radiation of Ultrashort-Pulse Antennas in Packet Mode
L. D. Bakhrakh and M. Ya. Izrailovich
pp. 432-436 Full Text: PDF (55 kB)
MECHANICS
On Statically Definable Relationships in Ideal-Plasticity Theory
D. D. Ivlev
pp. 437-440 Full Text: PDF (50 kB)
Three-Wave Resonant Interaction Involving Unstable Wave Packets
S. Yu. Annenkov and N. N. Romanova
pp. 441-446 Full Text: PDF (79 kB)
Statically Definable Relationships in Ideal-Plasticity Theory
D. D. Ivlev and M. V. Mikhailova
pp. 447-450 Full Text: PDF (50 kB)
Mass Transfer in a Stress Field Associated with Bending of a Bar
N. M. Vlasov and I. I. Fedik
pp. 451-454 Full Text: PDF (50 kB)
Inclusion of the Moment Interaction in the Calculation of the Flexural Rigidity of Nanostructures
E. A. Ivanova, A. M. Krivtsov, N. F. Morozov, and A. D. Firsova
pp. 455-458 Full Text: PDF (66 kB)
On Linearized Equations of Statically Definable Relationships in Ideal-Plasticity Theory
D. D. Ivlev and M. V. Mikhailova
pp. 459-461 Full Text: PDF (41 kB)Archived web conten
Particle Pairing In Complex Plasmas
No full textPairing of particles is a ubiquitous phenomenon in complex plasmas. The latter are suspensions of charged micron-size solid particles in a plasma, often in the (pre)sheath area above the lower electrode in a gas discharge [1]. Particle pairing was observed in various settings from isolated pairs and larger strings to pairs in 2D crystals and particle bilayers. An important role in the formation of particle pairs belongs to the plasma wakes that appear behind charged particles in the flow of ions. Fundamental questions are what determines the spatial extent of pairs and their stability. These questions recently received attention, but to the best of our knowledge no systematic study was done.
In this work, we systematically study the dependence of particle pair size on experimental parameters. We used an experimental setup based on a modified Gaseous Electronics Conference (GEC) radio-frequency (rf) reference cell [2]. Plasma was sustained by a capacitively coupled rf discharge in argon at the pressure of 2 Pa. Melamine-formaldehyde (MF) microspheres with a diameter of 9.19±0.09 μm were suspended in the (pre)sheath area above the lower rf electrode. The particle suspension was imaged from the top and side with two video cameras.
A specially designed "pair state" of complex plasma was prepared where particles formed multiple pairs that were vertically oriented, had a well-defined size, and levitated at the same height but were weakly coupled with each other and did not form any regular structure. As the discharge voltage was decreased, the pairs shifted downward and extended vertically. The vertical size of pairs was measured as a function of experimental parameters. We offer an interpretation of our observations based on a recent theory [3] that takes plasma non-uniformity into account.
[1] A. Ivlev, H. Löwen, G. Morfill, C. P. Royall, Complex Plasmas and Colloidal Dispersions: Particle-resolved Studies of Classical Liquids and Solids, Series in Soft Condensed Matter Vol. 5 (World Scientific, Singapore, 2012).
[2] V. Nosenko, A. V. Ivlev, and G. E. Morfill, Phys. Rev. E 87, 043115 (2013).
[3] R. Kompaneets, A. V. Ivlev, V. Nosenko, and G. E. Morfill, Phys. Rev. E, accepted (2014)
Shear-induced ordering in a liquid complex plasma
No full textA complex, or dusty plasma is a suspension of small solid particles in an ionized gas. Particles get charged by collecting electrons and ions from the ambient plasma and interact with each other via a screened Coulomb (Yukawa) pair potential. Complex plasmas are often strongly coupled and can exist in liquid and even crystallized forms.
In our experiment [1], polymer microspheres with a diameter of 9.19 μm were suspended in the plasma sheath above the lower electrode in a radio-frequency discharge in argon. The particle suspension self-organized in a highly ordered single-layer triangular lattice. Shear stress was applied to this plasma crystal by pushing a stripe of particles by the radiation pressure force of a rastered laser beam. We applied increasing levels of shear stress to the crystal. At low stress, the crystal deformed elastically. At higher stress, the following stages were observed: defect generation while in a solid state, onset of plastic flow, and fully developed shear flow.
We observed shear-induced reordering in a flowing liquid complex plasma. We made two related observations. First, a flowing liquid complex plasma is not completely isotropic. Rather, on top of an isotropic particle distribution appears a weak triangular order with Θ=0° (where Θ is the angle between the laser beam and the closely packed rows of particles) even in the cases when the original triangular lattice was oriented at 30°. Similar anisotropy in a liquid complex plasma was observed in [2], where the initial triangular order with Θ=0° was not completely destroyed in a shear melted state. Second, after the laser was switched off, the liquid complex plasma re-crystallized in a triangular lattice with Θ=0°, even though the lattice was oriented at Θ=30° before melting.
A flowing liquid complex plasmas, therefore, favors particle ordering where "closely packed lines" are oriented along the flow. The observed particle ordering is similar to the formation of particle strings aligned in the flow direction in sheared 2D colloidal dispersions [3] and simulated liquid of soft disks [4]. Here, we observed it for the first time in a sheared complex plasma.
[1] V. Nosenko, A. V. Ivlev, and G. E. Morfill, Phys. Rev. E 87, 043115 (2013).
[2] V. Nosenko, A. V. Ivlev, and G. E. Morfill, Phys. Rev. Lett. 108, 135005 (2012).
[3] E. J. Stancik, A. L. Hawkinson, J. Vermant, G. G. Fuller, J. Rheol. 48, 159 (2004).
[4] S. Butler and P. Harrowell, Phys. Rev. E 54, 457 (1996)
Role of effective potential barriers in the non linear screening regime:Grain charging and ion drag force.
No full text(INFN Sezione di Napoli
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