Kinetic theory of dusty plasmas and effective grain interactions

The basic points of the consistent kinetic theory of dusty plasmas is discussed. The equations for microscopic phase densities of plasma particles and grains are formulated. Using such equations it is possible to derive the kinetic equations, taking into account both elastic and inelastic particle collisions. Obtained equations are used for kinetic description of effective grain-grain potentials.Обговорюються основні положення послідовної кінетичної теорії запорошеної плазми. Наведено рівняння для мікроскопічних фазових густин для плазмових частинок і порошинок. Показано, що, використовуючи такі рівняння, можна сформулювати кінетичні рівняння для запорошеної плазми з урахуванням пружних і непружних зіткнень частинок та поглинання електронів та іонів порошинками. Розглянуто кінетичний опис ефективних потенціалів взаємодії порошинок у плазмі.Обсуждаются основные положения последовательной кинетической теории пылевой плазмы. Приведены уравнения для микроскопических фазовых плотностей для плазменных частиц и пылинок. Показано, что, используя такие уравнения, можно сформулировать кинетические уравнения для пылевой плазмы, учитывающие упругие и неупругие столкновения частиц и поглощение электронов и ионов пылинками. Выполнены кинетические расчеты эффективных потенциалов взаимодействия пылинок в плазме

Effect of plasma on the radio-technical characteristics of the Uragan-2M torsatron matching RF systems

There were carried out qualitative studies of the effect of plasma parameters during the RF disharge wall conditioning in a helium atmosphere on the quality factor of the antenna oscillating circuit at Uragan-2M torsatron. The quality factor is determined from the ratio of the electric current in the circuit to the feed current. The dependence of the quality factor of the toroidal steady magnetic field as well as on the helical field is analyzed. The dependence on the helical field is much stronger; with its increase the quality factor increases that is accompanied with reduction of the antenna load. Also, the ratio of idling current in the antenna (when the plasma even less) to the current in the antenna is measured during the discharge. The dependence of this parameter on the toroidal magnetic field and the neutral gas pressure is studied.Проведены качественные исследования влияния плазмы в режиме ВЧ-чистки в атмосфере гелия на добротность антенного колебательного контура в торсатроне Ураган-2М. Добротность определялась из отношенния тока в контуре к току подводящего фидера Q=Ik/If. Проанализирована зависимость добротности как от тороидального поля, так и от винтового. Зависимость от винтового поля значительно сильнее, с его ростом добротность увеличивается, что соответствует снижению нагрузки антенны. Также измерялся параметр Iaxx/IaL, т.е. отношение тока в антенне в момент холостого хода генератора (когда плазмы еще нет) к току в антенне в момент разряда. Приведены зависимости этого параметра от тороидального поля и от давления.Проведені якісні дослідження впливу плазми в режимі ВЧ-чистки в атмосфері гелію на добротність антенного коливального контуру в торсатроні Ураган-2М. Добротність визначалась з відношення струму в контурі до струму підвідного фідера Q=Ik / If. Показана залежність добротності як від тороїдального, так і від гвинтового полів. Залежність від гвинтового поля значно сильніше, з ростом поля добротність збільшується, що відповідає зниженню навантаження антени. Вимірювався також параметр Iaxx / IaL, тобто відношення струму в антені в момент холостого ходу генератора (коли плазми ще немає) до струму в антені в момент розряду. Виявлено також залежності цього параметру від тороїдального поля та від тиску

Effect of pressure on the magnetic properties of CrB₂

Magnetic susceptibility c of the itinerant antiferromagnet CrB₂ with TN ≃ 87K was studied as a function of the hydrostatic pressure up to 2 kbar at fixed temperatures 78 and 300 K. The pressure effect on c is found to be negative in sign and weakly dependent on the magnetic state of the compound. In addition, the measured pressure dependence of the Néel temperature, dTN / dP = (0.1 ± 0.1) K/kbar, is roughly two orders of magnitude smaller than the corresponding value for the pure chromium. The main contributions to c and their volume dependence are calculated ab initio within the local spin density approximation, and appeared to be in close agreement with the experimental data

Thermodynamics and kinetics of boundary friction

A deterministic theory describing the behavior of an ultrathin lubricant film between two atomically-smooth solid surfaces is proposed. For the description of lubricant state the parameter of excess volume arising due to chaotization of solid medium structure in the course of melting is introduced. Thermodynamic and shear melting is described consistently. Dependences of friction force on temperature of lubricant, shear velocity of rubbing surfaces, and pressure upon surfaces are analyzed. Within the framework of a simple tribological model the stick-slip mode of friction, when the lubricant periodically melts and solidifies, is described. The obtained results are qualitatively compared with the experimental data.Comment: 14 pages, 6 figures, 33 reference

Pressure effects on electronic structure and magnetic properties of anisotropic metallic compounds

Pressure effects on electronic structure and magnetic properties of anisotropic metallic materials (CrB₂, FeGe₂, LaFeAsO) are investigated. Magnetic susceptibilities of CrB₂ and FeGe₂ compounds were studied under hydrostatic pressure at fixed temperatures, 77 and 300 K. In order to analyze the experimental magnetovolume effects, the electronic structures were calculated ab initio in external magnetic field as a function of atomic volume by employing a full-potential LMTO method. The calculated field-induced magnetic moments and their volume derivatives compare favorably with the experimental pressure effects in magnetic properties of CrB₂ and FeGe₂. The main role of pressure in high-Tc superconductivity of LaFeAsO is found to reduce density of states at the Fermi level and to suppress ferromagnetic spin fluctuations

Sequence specificity for uridylylation of the viral peptide linked to the genome (VPg) of enteroviruses

Bio-organic Synthesi

Study of KS KL Coupled Decays and KL -Be Interactions with the CMD-2 Detector at VEPP-2M Collider

The integrated luminosity about 4000 inverse nanobarn of around phi meson mass ( 5 millions of phi mesons) has been collected with the CMD-2 detector at the VEPP-2M collider. A latest analysis of the KS KL coupled decays based on 30 % of available data is presented in this paper. The KS KL pairs from phi meson decays were reconstructed in the drift chamber when both kaons decayed into two charged particles. From a sample of 1423 coupled decays a selection of candidates to the CP violating KL into pi+ pi- decay was performed. CP violating decays were not identified because of the domination of events with a KL regenerating at the Be beam pipe into KS and a background from KL semileptonic decays. The regeneration cross section of 110 MeV/c KL mesons was found to be 53 +- 17 mb in agreement with theoretical expectations. The angular distribution of KS mesons after regeneration and the total cross section of KL for Be have been measured.Comment: 14 pages, 8 figure

Conformational dynamics and internal friction in homopolymer globules: equilibrium vs. non-equilibrium simulations

We study the conformational dynamics within homopolymer globules by solvent-implicit Brownian dynamics simulations. A strong dependence of the internal chain dynamics on the Lennard-Jones cohesion strength ε and the globule size N [subscript G] is observed. We find two distinct dynamical regimes: a liquid-like regime (for ε ε[subscript s] with slow internal dynamics. The cohesion strength ε[subscript s] of this freezing transition depends on N G . Equilibrium simulations, where we investigate the diffusional chain dynamics within the globule, are compared with non-equilibrium simulations, where we unfold the globule by pulling the chain ends with prescribed velocity (encompassing low enough velocities so that the linear-response, viscous regime is reached). From both simulation protocols we derive the internal viscosity within the globule. In the liquid-like regime the internal friction increases continuously with ε and scales extensive in N [subscript G] . This suggests an internal friction scenario where the entire chain (or an extensive fraction thereof) takes part in conformational reorganization of the globular structure.American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi