Table of contents

A general fermion system interacting with a time-periodic external field is discussed in the second quantization formalism transposed in the Fock-Floquet space. The method simulates the evolution of the system with the help of an auxiliary parameter which is analog to the time and defines the vectors associated to the states of the system, such that the matrix elements in the Hilbert space have a physical correspondence. Assuming that only the principal quasi-energies have physical relevance, the ground state of the free system is constructed in the occupation-numbers representation and an analog of Wick's theorem is derived. The perturbation series of the Green's functions is subsequently obtained, and the linear response of a given observable is expressed in terms of the correlation functions. The results have formal similarities to those of the standard theory of the many-particle conservative systems.

Relations of different star-products are studied for the SU(2) group – the standard one and the tomographic one (which is introduced in employment of a tomographic map for spin states). A deformed star-product commutator ("quantum" k-Poisson bracket) is introduced for functions on compact SU(2) group using the deformed star-product.

A four-velocity model and diffuse-reflection type boundary conditions are used to solve the molecular transport problem within a confined slender microdomain. The preliminary results show that there is a preferred motion related to the non-trivial velocity-slip fields for a range of Knudsen numbers if there is a non-boundary-driven force along the streamwise direction. As the Knudsen number increases, the value of the orientation associated with the discrete velocity (or the direction of the discrete velocity) resulting in this preferred motion decreases.

Multiconfiguration Dirac–Hartree–Fock (MCDHF) calculations for the 2s^{2   1}S₀ - 2s2p ³P₁ intercombination transitions are revisited for the elements N⁺³ - Mg⁺⁸, and for Fe⁺²² where previous results produced transition rates that were too small when compared with similar multiconfiguration Hartree–Fock- Breit–Pauli values. By optimizing on both the first and second eigenvalue for J = 1, the wave functions for the 2s2p ³P₁ state produced transition rates that are within the uncertainty limits of recent Breit–Pauli calculations. The case of C⁺² is also discussed where previous theory and experiment are in excellent agreement.

We present new energy-level classifications for over 400 lines in the spectra of neutral and singly-ionized dysprosium. These lines were observed using Fourier transform spectrometry of high current hollow cathode lamps and cover the wavelength range 230 nm to 1.6 µm. They were classified by 43 new energy levels of Dy I and 24 new energy levels of Dy II. The standard uncertainty of the energy levels and the strongest lines is estimated at 0.005 cm^-1.

The spectrum of six times ionized krypton, (Kr VII) has been observed in the 300–2100 Å wavelength range. We propose 11 new energy level values for the 4p4d configuration and we adjusted the previously known energy level values for the 4s5p, 4s4f, 4s5s and 4s5d configurations. A total of 56 new lines in this spectra have been classified. The observed configurations were theoretically interpreted by means of Hartree–Fock relativistic, (HFR) calculations and least-squares fit of the energy parameters to the observed levels.

We study soliton solutions of the path-averaged propagation equation governing the transmission of dispersion-managed (DM) optical pulses in the (practical) limit when residual dispersion and nonlinearity only slightly affect the pulse dynamics over one compensation period. In the case of small dispersion map strengths, the averaged pulse dynamics is governed by a perturbed form of the nonlinear Schrödinger equation; applying a perturbation theory – elsewhere developed – based on inverse scattering theory, we derive an analytic expression for the envelope of the DM soliton. This expression correctly predicts the power enhancement arising from the dispersion management. Theoretical results are verified by direct numerical simulations.

The influence of the Alfvén wave on the electron distribution function is studied by numerical simulations. A quasi-linear operator models the electron Landau damping of any plasma eigenmodes: kinetic Alfvén, whistlers, and lower hybrid waves. Weak collisions are taken into account via 2D in the velocity space nonlinear Fokker-Planck kinetic equation. It is shown that due to the variation of phase velocity, as seen by the Alfvén wave in the course of propagation in the nonuniform magnetic field, the noninductive current induced by the Alfvén wave and the dissipated wave power may be several times larger in comparison with the case when the phase velocity is constant. The results might be applied in coronal regions, magnetosphere, tokamaks, stellarators.

Drawing on the predominant belief in colloidal science, it is frequently supposed that the interaction responsible for colloidal plasma crystals should be repulsive. This work presents a model which shows that this interaction can indeed be attractive, depending on system parameters. A long range attractive well associated with the electrostatic interaction results by accounting for both plasma grain correlations and finite value for the product of the Debye wave vector and grain radius, k_Da. These results have implications for the analogous problem in colloidal science.

The radial distribution function (RDF) of amorphous Ge and Si is calculated by assuming that the materials consist of elastically deformed nanocrystals of diameter about 3 nm. Good agreement with the experimental RDF is achieved, in particular for deformed hexagonal rather than cubic nanocrystals. This model provides a continuous connection from amorphous via nanocrystalline to coarse-grained crystalline materials.

The S = 1 and S = ½ alternating Heisenberg antiferromagnetic spin chain with single-ion anisotropy in the presence of an applied magnetic field is investigated on the basis of the Schwinger boson mean-field theory. The specific heat, the susceptibility and the magnetization as functions of temperature, the anisotropy as well as the applied field are discussed, respectively. The energy spectrum as a function of both the external field and the anisotropy is obtained. The results indicate that the single-ion anisotropy does not change so much the features of the specific heat, while the susceptibility, the magnetization and the energy gaps are remarkably affected by the external field and the anisotropy. It is observed that with varying the external field a magnetization plateau exists at very low temperature. The system appears to exhibit a ferrimagnetic longe-range order for both h ≠ 0 and D₁ ≠ 0 in the ground state. Our results are compared with those obtained by other methods.

This paper focuses on a single fluid, two-dimensional, axisymmetric, time-dependent, magnetohydrodynamic numerical simulation of the formation and evolution of a coronal streamer in a current sheet.

Two types of evolution are described: (a) the disruption of the streamer in a CME and (b) the dissolution of the streamer probably caused by the current sheet dissipation in the solar atmosphere. In the first case, the ejected plasmoid density reaches 21 × 10⁹ cm^-3 at 8 solar radii from the Sun; in the second case, the maximum density attained is about 5 × 10⁹ cm^-3. The temperature does not exceed 5 × 10⁶ K. These plasma parameters fit well the observations.