Table of contents

We consider a nonlinear bi-inductance electrical transmission line which simulates a diatomic chain with non-linear cubic interactions. The linear spectrum of this model exhibits a gap which is proportional to the linear inductance difference. We analyse theoretically and numerically the coupled nonlinear excitations of such a bi-inductance line, which have a similar origin as the well-known gap solitons (GS) appearing in nonlinear systems with a spatial periodicity. Otherwise, these nonlinear modes are found in terms of asymmetric GS (kinks type) and are long-lived non-linear excitations.

We study anisotropic quantum spin chains in an aperiodic magnetic field h_n = λ cos(2πσn^v); for 0 < v < 1. For v equal to unity and σ equal to the golden mean, the system is quasiperiodic. In the isotropic limit, the incommensurate behaviour is described by the Harper equation exhibiting the metal-insulator transition whereas in the anisotropic case a new fat critical phase is observed between the extended and localized phases. For v different from unity, the global extended phase of the quasiperiodic anisotropic model is replaced by the metal-insulator transition with mobility edges. The mobility edge corresponding to the isotropic model exhibits a novel intermittency. In addition, a new mobility edge with no analog in the isotropic model appears at energy corresponding to the spin space anisotropy g. Instead of the fat critical phase of the quasiperiodic model we now observe a phase which is localized everywhere except at the energy equal to g. There is no localization-delocalization transition in this case. Various high precision numerical tools suggest the existence of critical states at the onset of metal-insulator transition, along the line where the energy is equal to g as well as at the conformally invariant point. We conjecture that the existence of critical states at a conformal point is a universal phenomenon for all aperiodic potentials.

The coupled map lattice by Olami et al (1992 Phys. Rev. Lett.68 1244) is "doped" by letting just one site have a threshold, T_max^*, bigger than the others. On an L × L lattice with periodic boundary conditions this leads to a transition from avalanche sizes of about one to exactly L², and after each avalanche stresses distributes among only five distinct values, τ_k, related to the parameters α and T_max^* by τ_k = kαT_max^* where k = 0, 1, 2, 3, 4. This result is independent of lattice size. The transient times are inversely proportional to the amount of doping and increase linearly with L.

The absolute transition probabilities for 28 Si II spectral lines have been determined by measurement of emission line intensities from laser-produced plasmas of Si in Ar and Kr atmospheres. The studied plasma has a temperature of about 2 × 10⁴ K and 10¹⁷ cm⁻³ electron density. The local thermodynamic equilibrium conditions and plasma homogeneity have been checked. The results are compared with the available experimental and theoretical data and with present Hartree-Fock calculations in LS coupling.

The spectra of antimony and tellurium were photographed in the 100–200 Å region on grazing incidence spectrographs at Moscow, Russia and NIST, USA laboratories. The 4d⁹ −[4d⁸6p + 4p⁵4d¹⁰] transition array of Sb VII was analyzed. 31 levels in Sb VII were established. 41 new lines in Sb VII belonging to the 4d⁹ −(4p⁵ 4d¹⁰ + 4d⁸6p) transition array have been classified. Seven lines each in Sb VII and Te VIII belonging to the 4d⁹ −4d⁸4f transition array have been classified. Parametric least-squares-fitted calculations involving configuration interaction have been carried out to interpret the spectrum satisfactorily.

Expressions for the average energy, variance and skewness of Auger spectra are presented. These characteristics have been calculated for the M_{4, 5}N_{4, 5}N_{4, 5} spectra of free atoms with open 5p^N shell and for the N_{4, 5}N_{6, 7}N_{6, 7} spectra of lanthanide atoms; a comparison with the global characteristics of the registered spectra is given. The transition zones of the Auger spectrum are introduced. These zones characterise the participation of the initial and final configurations in Auger transitions. It is shown, that the effect of narrowing takes place in Auger spectra as it does in characteristic emission spectra.

On the basis of experimental data on multiple-ionization cross sections σ_n of neutral atoms by electron impact a semiempirical formula for σ_n, n ⩾ 3, has been deduced where n is the number of ejected electrons. It has been shown that the cross section σ_n depends on three atomic parameters: the minimal ionization energy required to remove n electrons from the target, the total number of target electrons and the number of ejected electrons. The electron-impact energy dependence of the cross sections σ_n with different n is described by one universal function. As the number of ejected electrons n increases the cross section σ_n falls off approximately as σ_n ~ n⁻⁶.

A comparison of σ_n calculated by the proposed semiempirical formula with available experimental data for the atomic targets from Ne to U and the number of the ejected electrons from n = 3 to n = 13 has been performed.

For the first time, the formula suggested can be used for estimation of multiple-ionization cross sections σ_n, n ⩾ 3, from threshold up to high electron energies E ≈ 10⁵ eV for an arbitrary atomic target.

The energies and wave functions of the 1s²2p^{2 1}S, ³P and ¹D states are calculated with a full-core plus correlation method (FCPC) for ions from B II to Ne VII, Mg IX and Si XI. A restricted variational method is used to extrapolate a better nonrelativistic energy. The relativistic correction and fine structures are calculated with first-order perturbation theory. Higher order effects are estimated. The oscillator strengths for 1s²2snp (n = 2, 3) ¹P^o–1s²2p^{2 1}S, ¹D and for 1s²2snp (n = 2, 3) ³P^o–1s²2p^{2 3}P are calculated. The results are compared with available theoretical and experimental data in the literature. The excitation energies predicted in this work are slightly higher than the precision experiment. For example, for ¹D, it is higher by 8.5 cm⁻¹ for Z = 4 and the discrepancy increases to 149 cm⁻¹ for Z = 14. The dipole-length, -velocity and -acceleration oscillator strengths calculated in this work agree well with each other. However, some discrepancies still exist between the predicted oscillator strengths and experiment.

An illustrative analysis of the magnetic shielding factor offered by a circular cylindrical anisotropic shell reveals the expedience of undertaking in-depth theoretical and experimental research efforts in the field of diverse electromagnetic shields based on anisotropic materials. Such efforts may promote the development of new technologies for producing materials with an adequate degree of anisotropy and thereby provide dramatically improved shielding performance.

The results associated with the nonlinear theory of surface magnetoplasma waves (SW) propagating across an external magnetic field at a solid-state plasma-metal interface are presented. In a weak nonlinearity approximationg using a formalism of third-order nonlinear susceptibilities the nonlinear frequency shift of the SW is calculated. The possible nonlinear mechanisms which influence the SW propagation are discussed. In several cases the comparison of the obtained results with previous papers gives a possibility to estimate the third order nonlinear susceptibility of the nonlinear medium bounded by a metal.

A powerful numerical algorithm is described for calculating the micromaser spectrum. The method can be extended as a tool for computing the dynamics of the field density matrix which describes the photon field inside the micromaser cavity. An expression for the micromaser spectrum is also discussed, from which the role played by the initial state in the build-up of the spectrum becomes clearly distinguished from the micromaser dynamics.

Light induced hydrodynamic flows of strongly absorbing particles suspended in a transparent liquid was experimentally realized. The formation of traps for particles resulting from contrary flow collisions was firstly revealed.

A system for high-magnification transformation of optical information recorded on a liquid crystal matrix by computer was experimentally realised. It was shown that the highest contrast can be reached in the conjugated resonator scheme using reflecting negative component. A multi-channel system was considered that allows one to obtain a large vision field or high resolution. The ways to perfect the system were indicated.

The effect of the presence of self-generated magnetic fields on the growth rate of the Raman backscattering instability in a homogeneous plasma is investigated. A general expression for the growth rate of Raman backscattering has been derived analytically. This expression shows that there is a reduction in the growth rate of the instability due to the existence of the self-generated magnetic fields.

A new form of nonlinear Schrödinger equation in three-spatial dimensions is deduced for a plasma consisting of both positive and negative ions placed in a uniform magnetic field. Such an equation essentially describes the space evolution of a nonlinear drift wave. We have used it to ascertain the extent of self focusing of a drift wave in such a plasma. The zones of transversal stability are obtained numerically and their variation with respect to various plasma parameters are studied.

Generic fetures of nonlinear wave interaction in continuous plasma-like media are studied. Relationship between conservation laws, symmetries and directions of turbulent mode cascades in anisotropic media, such as inhomogeneous magnetized plasmas, is established. Momentum conservation in nonlinear interaction between collective modes results in a universal form of preferential inverse (or direct) energy cascade with respect to wavelengths. When the total wave energy is invariant in nonlinear interaction, double cascade of energy and momentum with respect to inverse phase velocities or wavelengths occurs. Cascade directions are determined by energy spectra of quasiparticles-waves. Excitation of zonal flows in nonlinear wave interaction appears to be a general consequence of energy-spectrum anisotropy. Possibility of wave condensation and subsequent turbulent instability in the sea of weakly nonlinear waves is suggested.

Generic constraints on energy transfer in inhomogeneous magnetized plasmas and on plasma stability are derived within the context of the quasiparticle description. Their relation to the problem of turbulent fluctuations driven by temperature gradients is discussed in regard to temperature gradient thresholds and sufficient conditions for stability.

Using a two fluid plasma description we study simultaneous effects of the magnetic field shear, and variation of curvature-related terms along the field lines, on drift waves. This variation leads to a linear coupling of different modes which can change the stability of the system by complete elimination of the shear effects.

This analysis shows that a short-range interaction potential approximates parameters of inert gas crystals better than the Lennard-Jones one. A method is developed for calculation of the atom binding energy of clusters of the face-centered cubic (fcc) and hexagonal structure. It uses the short-range character of interaction of atoms that leads to interaction between nearest neighbors of the cluster only. Symmetric figures of these clusters with magic numbers of atoms are considered. Energies of clusters of fcc, hexagonal and icosahedral structures are compared for a short-range interaction between atoms.

Fluorescence time evolution on picosecond time scale and fluorescence quenching by electric field have been studied in two organic photo-conductor - perylene tetracarboxylic acid diimide pigments. The fastest components of complex fluorescence decay were measured to be as short as 5.5 ps and 15 ps for the two samples investigated. The electric field induced fluorescence quenching was observed to be of "rate" type where the initial fluorescence amplitude remains constant but the lifetime decreases.

We calculate the coefficients of electric conductivity and the electronic component of the heat conductivity of disordered transition metals, possessing relatively low electric resistance. Amorphous, liquid and also simple and nonmagnetic transition metals are considered from a unified point of view. For the conduction electrons the approximation of almost free electrons was used. As the main mechanisms causing the conduction electron scattering were chosen: the electron-ion interaction, the s-d hybridization potential of the conduction electrons and the electron-phonon interaction. Within the framework of the previously elaborated method by V T Shvets, the inverse relaxation times for various kinetic processes were evaluated in the second order of perturbation theory taking into account the first two of scattering mechanisms mentioned above and in the infinite order in electron-phonon interaction. We also introduced and evaluated a new structure function of the metals under consideration. The temperature dependence of the kinetic coefficients was examined over a wide range of temperatures.

In this paper, some unusual atmospheric lights observed in Norway have been explained as the results of nonlinear wave-particle interactions based on turbulent plasma theory and wave-vortex interaction as well as laboratory experiments on rocks. The paper also points out that the atmospheric lights have provided evidence for the vortex structure of fireballs and for the physical mechanism of wave-particle interaction for the formation of plasma ball lightning and solitons.