Table of contents

The quantum and classical equations are found which govern the motion of toroidal moments in an external magnetic field. The concrete realization of toroidal moments of higher multipolarities is given, and it is shown how the toroidal moments interact with each other. We recover the 3-dimensional analogue of the Aharonov-Casher effect. It turns out that the toroidal moments should exhibit quantum scattering on the Coulomb centre.

In this paper the evolution of a quantum system driven by a non-Hermitian Hamiltonian depending on slowly-changing parameters is studied by building an universal high-order adiabatic approximation (HOAA) method with Berry's phase, which is valid for either the Hermitian or the non-Hermitian cases. This method can be regarded as a non-trivial generalization of the HOAA method for closed quantum system presented by this author before. In a general situation, the probabilities of adiabatic decay and non-adiabatic transitions are explicitly obtained for the evolution of the non-Hermitian quantum system. It is also shown that the non-Hermitian analog of the Berry's phase factor for the non-Hermitian case just enjoys the holonomy structure of the dual linear bundle over the parameter manifold. The non-Hermitian evolution of the generalized force harmonic oscillator is discussed as an illustrative example.

The mass of ²⁸Si has been determined to be m(²⁸Si) = 27.976 926 57(30) u by comparing the cyclotron frequencies of the singly charged ions ¹²C⁺, ¹²C⁺₃ and ²⁸Si⁺ in a Penning trap mass spectrometer. The experimental technique and the setup are described. The obtained accuracy as well as possible improvements are discussed. Our measurements are related to current efforts to base the kilogram on atomic properties by using an almost perfect single crystal of silicon.

The design of the CRYRING electron cooler, including magnets, electron gun and collector, and the vacuum system, is described. Light and heavy atomic ions and molecular ions have been cooled at ion energies between 0.29 and 10.9 MeV per nucleon. Experiments in atomic and molecular physics have been performed using the cooler both for beam cooling and as an electron target. Measurements of longitudinal drag forces and resulting estimates of transverse and longitudinal electron temperature are presented.

The spectrum of seven times ionized sulfur, S VIII, has been observed in the wavelength range 50-1200 Å. Both beam-foil and laser-produced plasma light sources have been used. 71 new lines representing the transitions 2p⁵-2p⁴3d, 2p⁴3s-3p, 3p-3d, 3d-4f, 4f-5g and 5g-6h have been identified and 100 energy levels, of which 46 are new, are now accurately established. The spectral analysis is supported by isoelectronic comparisons along the F I-sequence and by parametric least-squares fits of Slater integrals to the observed levels. The ionization potential in S VIII is determined to 2 651 899 ± 60 cm⁻¹ and estimated ionization energies are derived for the isoelectronic elements between F I and Ar X.

The transition arrays 3p³, 3s3p3d-3p²3d, 3s3d² have been identified in the spectra of aluminium-like K VII-Ni XVI ions, excited in a laser-produced plasma. On the basis of this identification the energies of the essential part of the levels of the 3p²3d and 3s3d² configurations and the 3s3p3d⁴F term have been determined for the first time in these ions. The identifications are supported by the multiconfiguration Hartree-Fock calculations.

State selective total and differential cross sections for charge exchange collisions between N³⁺ ions and atomic H have been calculated for incident ion energies ranging from 10 to 1000eV/amu. Over the whole energy range capture to the 3s level of N²⁺ dominates. The influence of translation effects on both the total and differential cross sections is analysed in detail. Only when translation effects are accounted for, is it possible to reproduce the experimental total cross sections for energies above 100eV/amu. On the other hand, the position of the maxima and minima in the differential cross sections depend only weakly on translation effects.

The optical excitation functions of 15 lines and the polarization degree of 6 lines of Ba⁺ ions were measured using crossed beams of electrons and neutral barium atoms. The electron impact energy was varied from the threshold up to 300eV. The atomic density was less than 5 × 10¹⁰ cm⁻³. Nine excitation functions were measured for the first time. The excitation cross-sections of the ionic lines were obtained relative to that of the atomic resonance line 6 ¹S-6 ¹P (5535 Å), normalized to the Bethe theory in the high-energy limit. Measured cross-sections for the 6 ²S_1/2-6 ²P_3/2 and 6 ²P_3/2-7 ²S_1/2 transitions are compared with other experimental results. The total uncertainties vary from 10% for the 6 ²S-6 ²P up to 46% for the 6 ²P_3/2-7 ²D_3/2 and 6 ²P_3/2-8 ²S_1/2 cross-sections. The polarization degree of 5 ionic lines were measured for the first time. The polarization function of each line exhibits oscillatory structure in the threshold region.

Systematic variational calculations using the multi-configuration Hartree-Fock method for Li are reported. For 1s²2s²S of Li, an nl-expansion is attempted in configuration space, similar to a partial wave expansion for helium-like systems. The total energy, ionization energy, specific mass shift, and hyperfine contact term are calculated with respect to increasing size of the configuration set. A comparison is made with n-expansion in configuration space, which is found to be the more efficient method. The total energy obtained from our variational procedure is lower than that of a previously reported partial wave study on ground state of Li. Similar n-expansion studies are performed for 1s²2p²P. For the latter, the 2s-2p transition integrals are reported, showing convergence of the transition energy as well as the length and velocity form of the f-value.

The instability of the plane interface separating two superposed gravitating homogeneous streaming rotating fluids is studied here. The fluids are assumed assigned to be permeated by a uniform horizontal magnetic field. The longitudinal mode of wave propagation when the fluids are rotating about the axis of the magnetic field is discussed. The streaming motion is taken in the direction of the magnetic field.

The dispersion relation has been derived. The critical wave number for the instability when two fluids of the same homogeneous density stream past each other in opposite directions with the same velocity is obtained. It is found that the critical wave number is independent of the effects of rotation and magnetic field and depends upon the streaming velocity only. The streaming velocity has a destabilizing influence on the stability of the system as the critical wave number, below which the system is unstable, increases with increasing streaming velocity.

This paper deals with the correlation of substantive acceleration fluctuations in a stationary homogeneous turbulence which is invariant under translations and rotations but lacks reflectional symmetry. Appropriate invariant forms are considered for some second and third order correlation tensors, formed from the fluctuating components of velocity, acceleration, components of external force and pressures. For closure of the problems, quasi-normality hypothesis which relates fourth order correlation to second order correlation as in a normal distribution, is employed. Explicit analytical expressions are found for the scalar functions defining the correlation of substantive acceleration fluctuations.

A possibility for amplification of image brightness in a strontium vapor has been pointed out for the first time. A regime for image intensification in the violet spectral region has been realized experimentally. An increase in image sharpness was investigated theoretically for a multipass self-conjugate optical system with an active medium.

On the basis of the equations of hydrodynamics the radial temperature distribution of charged particles in surface wave produced plasmas is investigated, taking into account the nonlocal heating effect caused by the enhanced radial component of the electric field in the presence of a plasma resonance region. It is shown that because of the latter effect the maintenance of the discharge may be mostly due to the enhanced radial component of the surface wave. The temperature of electrons and ions are shown to have maximum values near the wall of the discharge tube.

The influence of associative ionization and autoionization on the electron velocity distribution function (EVDF) in natural conditions of low temperature high frequency (HF) gas discharges is investigated. The jump of the EVDF derivative with respect to electron velocity due to these ionization processes is calculated as a function of HF gas discharge parameters. The effect of the associative ionization on the nonstationary EVDF at the beginning of gas breakdown is described. Conditions of an experimental visualization of the EVDF derivative jump are established.

The influence of dielectronic recombination (DR) on the charge state and energy loss of fast heavy ions flowing through a target plasma of ICF interest is shown to be strongly modulated by the projectile deceleration. The inclusion of stopping effects prevents the appearance of an equilibrium charge, so that DR plays a far smaller role than recently advocated.

The characteristics of a self-sustaining magnetically confined electron cloud under different electromagnetic fields and pressures are studied by means of the rf method and the charge collection method. The electron cloud has been obtained at lower background pressures by a cold-cathode Penning discharge. The electron density of the cloud increases with the applied voltage, and with the magnetic field as well, if the electron cloud is in the unsaturated state. The density of a saturated cloud is independent of the magnetic field. When the pressure exceeds a critical value the electron cloud will be transformed into a neutral plasma.

The modulation instability of dust acoustic wave is investigated for the cold dust and hot ion and electron background. It is found that the Dust Acoustic Wave is modulationally unstable for λ_dek_c ⩾ 2.203. The stability depends critically on δ = n_io/n_eo for different values of η = T_e/T_i. The charge number Z does not effect the stability threshold lines.

The Kolmogorov spectra of low-frequency short-wave potential and magnetic fluctuations are obtained in a plasma with finite ion and electron pressures, β_i ∼ β_e ∼ 1. Magnetic nonlinearities are found to make the dominant contribution to the renormalized width of the convective spectrum and result in its essential broadening, that gives rise to a reduced anomalous electron heat conductivity.

The mechanism of the phase transition solid-liquid is analyzed for condensed rare gases that are modeled as a system of bounded atoms with short-range interaction. A widespread mechanism of the process according to interaction of vacancies is not acceptable in this case, and the phase transition is determined by interaction of vibrations of atoms through transition between cubic face-centered and icosahedral structures of clusters inside the system.

The dynamics of evaporation and spreading of solid islands and droplets of very viscous volatile fluids on a two-dimensional substrate are studied with Monte-Carlo simulations. A solid-on-solid model is used, where inclusion of an anisotropic interaction between the first and the second molecular layers enables simulations of surface evaporation and spreading of different thin film systems. The simulations are done under non-equilibrium conditions for which the final stage is a completely dry surface. Starting from complete layers, or solid Stranski-Krastanov islands and droplets of a volatile viscous fluid we have calculated local and global roughness of the solid substrate. Snapshot pictures for visualization of the kinetics will also be shown. Our results give qualitative criteria for layer-by-layer evaporation of these systems. In addition, we demonstrate the changes in the morphology of Stranski-Krastanov islands at different stages of evaporation and spreading, in analogy with corresponding profile formation under reverse growth conditions. We also discuss qualitatively the effects of temperature and diffusion to evaporation processes.

We investigate the existence of surface polaritons as a function of filling fraction f for a semi-infinite metal/insulator and a metal/metal superlattice respectively. A particular feature found is the existence of a special so-called stop mode having a limited existence region in momentum space. It is limited below by the light line and has an upper cut-off depending on the filling fraction f. The superlattice thus offers a unique possibility to systematically control this range by the proper choice of material parameters.

We investigate here the effect of non-magnetic impurities on the SDW state of the two-dimensional electron gas at half filling. The dependence on the impurity concentration (n_i) of the relevant SDW quantities is obtained within an Abrikosov–Gorkov-type approach. To account appropriately for the actual Fermi surface topology we introduce a classification of the electron-impurity scattering processes. Analytic results are obtained for a general type scattering in the limit of low- and high n_i-values. In addition, the presently introduced classification allows us to find a (rather general) class of scattering processes for which analytic results can be derived for arbitrary n_i values. The logarithmic singularity in the density of electronic states turns out to have a notable (qualitative and quantitative) influence on the SDW properties in the presence of impurities. The limitations of the presently employed approximations are also discussed.

Assuming that the zero point angular momentum is conserved the phenomenon of zero point spin reduction (ZPSR) has been explained pictorially using the mechanism of spin motion. Field independence and the gradual suppression of ZPSR corresponding to the external magnetic field applied parallel and perpendicular to the antiferromagnetic axis respectively, are also discussed.

We report results from simultaneous observations of geomagnetic activity and ionospheric absorption of cosmic noise performed at the antarctic stations Belgrano and San Martin. Common and deviant features in the two types of events are revealed by cross-correlation analysis and spectral analysis. Dynamical spectra, computed by sliding the analysis interval every 15 min, provide a good spectral characterization of geomagnetic and absorption events. Three distinct spectral bands have been found in most of the computed spectra, which reveal a different level of absorbed or released power over definite intervals of frequency. Cross-correlation analysis shows also regular variations of the best correlation, which drifts in the course of the events. Persistence of these features over prolonged periods suggest that they may be a manifestation of some permanent characteristic of the medium, which is not well understood.