Inhomogeneity of a harmonically confined Yukawa system
A crystalline system of strongly screened Yukawa particles in a harmonic trap is under consideration. We show that structural and dynamic properties of confined Yukawa crystals are fundamentally nonuniform. The average interparticle distance, thermal oscillation amplitude, and Lindemann and inverse coupling parameters are found to increase with the radial distance from the center of a structure. We verify the inhomogeneity of these parameters by molecular dynamics simulations and the analytical approach. Analytical formulas are in good agreement with a dusty plasma experiment. The obtained results might be important for the theory of crystal formation and phase transitions in dusty plasmas, colloidal suspensions, and Coulomb crystals.
Average distance between particles of dust in dusty plasma crystals is sensitive to the temperature of neutral atoms in a glow discharge plasma. In some experiments a significant decrease of average inter-particle distance after cooling to low temperatures is observed: the distance at 100 K is up to 4 times less than at 300 K. In this work dusty plasma system is studied by the method of numerical solving of Newton equations which is similar to the method of molecular dynamics. It is shown that the model of dusty plasma interaction including only the Debye potential and electrostatic parabolic trap may be not enough to explain this effect. Adding ion shadowing potential to this model increases the difference between the values of inter-particle distance at 100 and 300 K by 2–3 times. Comparison of theoretical results with experiments of other groups shows that some of the experimental points may be well approximated by this model.
Linear and nonlinear waves in the near-surface plasma at Phobos and Deimos are considered. It is shown that the motion of the solar wind relative to photoelectrons and charged dust grains violates the isotropy of the electron distribution function in the near-surface plasma at the Martian satellites, which leads to the development of instability and excitation of high-frequency waves with frequencies in the range of Langmuir and electromagnetic waves. Moreover, the propagation of dust acoustic waves, which can be excited, e.g., in the terminator regions of the Martian satellites, is possible. Solutions corresponding to the parameters of the plasma-dust systems over the illuminated parts of the Phobos and Deimos surfaces are found in the form of dust acoustic solitons. The ranges of possible Mach numbers and soliton amplitudes are determined.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.