Table of contents

The recent precise Cosmic Microwave Background Radiation (CMB) measurements by COBE and other facilities can provide interesting possibilities for the experimental checking of some basic physical parameters. In this context the inverse Compton scattering of highly monochromatic and parallel electron beams on laser photons is proposed for testing special relativity and related basic principles. For CEBAF and SLC parameters, for example, one can expect a precision for the isotropy of the speed of light dc(θ)/c ≈ 10⁻¹³ – 10⁻¹⁴ and an upper limit for the hypothetical fundamental length λ_f ≃ 10⁻²² – 10⁻²³ cm. In particular, of special interest can be the checking of the isotropy of the speed of light with respect the direction of the CMB dipole (a kind of Michelson-Morley experiment relative to the absolute "rest" coordinate system).

The integrals of motion are constructed for the Sutherland hyperbolic quantum systems of particles with internal degrees of freedom (SU(n) spins) interacting with an external field with the Morse potential of an arbitrary strength τ². These systems are confined if some constraint is imposed on τ, the strength λ of the pairwise interaction and the number of particles. The ground state is described by the wave function of the Jastrow form. The known results for the systems with inverse-square interaction within harmonic well are reproduced in the limit τ → ∞.

We extend our study of thermodynamics of a Kubo particle to temperatures smaller than the mean interlevel spacing. We obtain the distribution functions of spin susceptibility and heat capacity for Poisson and Wigner-Dyson level statistics. We evaluate the line shape of the Knight shift due to spin effects both in a single particle and for the ensemble average and compare it with orbital and spin-orbit contributions.

A mathematical model for the end section of a superconducting dipole magnet coil is presented. Magnetic field calculation methods concerning the evaluation of the flux density produced by the coil and the ferromagnetic yoke are discussed. The validity of the results is tested using finite element methods. The end section is optimized to have a peak flux density lower than 93% of that in the straight section. The integrated multipole analysis is in addition carried out.

On the basis of CBE calculations (Coulomb-Born approximation with exchange) of direct single ionization cross-sections, the fitting parameters were evaluated for the cross-sections σ and Maxwellian rate coefficients ⟨vσ⟩ of the target states 1s ⩽ nl ⩽ 6h and for the l-averaged values of σ and ⟨vσ⟩. The data made it possible to extrapolate the fitting parameters to arbitrary n-states with n ⩾ 7. The asymptotic behaviour of ionization cross-sections at high incident electron energies is considered as well. The results are compared with experimental data and other calculations.

Experimental values of pressure broadening and shift parameters of the 326.1 nm Cd line perturbed by Ar are measured and compared with those calculated from the impact theory for different interaction potentials.

Stark widths of three S III spectral lines belonging to 4p–5p transitions have been measured and calculated. Measurements have been performed in a low pressure linear pulsed arc at 2.1 × 10²³ m⁻³ electron density and 40 000 K electron temperature. Calculations for S III lines were performed by using the modified semiempirical approach. For S IV 4s ²S–4p ²P^o multiplet, calculations were performed within the semiclassical perturbation formalism. The obtained results were compared with other theoretical and experimental data.

Double electron capture by fast bare ions in helium is studied in the framework of the Four-Body Continuum Distorted Wave theory. It is shown that experimental data is well reproduced when the theoretical total cross-section include both contributions from the ground state and from the first singly excited states. In addition, cross-sections for the production of the first doubly excited states are also calculated. Present results call for additional experimental data at higher impact energies than presently available.

Lifetimes are reported for the twelve levels of the 4d⁹5p configuration in Pd-like In IV, measured using beam-foil excitation. Isoelectronic trends are studied through comparisons with earlier measurements for Cd III and Ag II.

The spectra of osmium and iridium were photographed in the 200-400 Å region on a 3 m normal incidence and 10.7 m grazing incidence spectrographs. The light sources used were triggered and sliding sparks. The 5d²-5d5f transitions in Os VII and Ir VIII were analysed. Eighteen of 20 levels of the 5d5f configuration in each spectrum have been established. Seventy-two lines of Os VII and 58 lines of Ir VIII have been classified. Least-squares fitted (LSF) and Hartree-Fock (HF) calculations were carried out to interpret the observed spectra.

Oxygen gas was bombarded by ions of H₃⁺ with an energy of 1 MeV, and the emission spectrum recorded in the wavelength range 320-950 nm. Numerous spectral features from excited states in O, O⁺ and O₂⁺ were observed. The emission lines from the atomic ions (but not from neutral atoms) were found to be Doppler broadened, indicating that these excited ions result from the energetic fragmentation of molecules. The light emission of principal spectral features has been studied as a function of gas pressure, and the observations elucidate the different contributions of projectile ions and electrons to the excitation process. Such pressure curves may also be useful for line classification.

Efficient continuous generation of UV radiation from a flow of neon plasma doped with copper vapor is demonstrated to be feasible.

It is well accepted that axisymmetric turbulent air-bubble plume in water can be described by any two of the three equations e.g. continuity equation, momentum equation and the kinetic energy equation. The approach in this paper, is based on the first two of these equations and the assumption that the width of the plume grows exponentially with the vertical distance measured from the exit lavel. Taking proper account of the slip velocity between the liquid and the gaseous phases, the centre-line velocities, the relative entrainment coefficient and the Froude number are computed numerically and discussed. The distribution of the centre-line velocity obtained with this model is found to be in good agreement with the widely accepted data of the experiment on turbulent air-bubble plume by H. E. Kobus (Proc. 11th Conf. Coastal Engineering, London, 1968, vol. 2, p. 1016.)

An experimentally simple scheme is proposed for obtaining complementary pairs of dark and bright pulses of adjustable width and contrast. The performance is based on a control-pulse disturbed total internal reflection of a probe beam at a nonlinear interface. The scheme seems attractive for generating of ultrashort dark/bright pulses in a broad range of wavelengths.

Wave propagation in a dusty magnetized plasma at frequencies below and of the order of the ion-cyclotron frequency, and with a non-zero electron temperature is considered. The general dispersion relation for waves propagating at an arbitrary angle with respect to the external magnetic field and for finite ion-cyclotron frequency is derived and discussed. Modification of the Alfvén resonance absorption mechanism due to the presence of a finite proportion of the negative charge of the plasma on stationary dust grains is investigated.

A dense jet of a plasma consisting of multiply charged ions was generated in the interaction of a laser plasma with a strong external axial magnetic field. It is shown that using the high-luminosity x-ray spectroheliograph technique allows to measure plasma emission spectra with 2-dimensional spatial resolution even in the cases when these spectra have small intensities. The x-ray spectroscopy and interferometry methods are used to measure plasma parameter distributions. The dependencies of N_e(z) and T_e(z) measured in this paper can be used to calculate the evolution of plasma ionization state during plasma expansion. The quasihomogeneous laser jet, which appears when a laser plasma interacts with an external magnetic field can be used not only to form an active medium of a short wavelength laser, but probably also to tackle the urgent problem of transport in a laser ion injector.

It was observed that an electron energy distribution function (EEDF) in a nitrogen afterglow plasma has two Maxwellian distribution in a thermal region and a vibrational excitation region with temperatures of T_e and T_v (equal to the vibrational temperature of molecules), and that the magnitude of T_v is greater than that of the stationary state of T_e. A new method is proposed for the determination of the molecules vibrational temperature by measuring the EEDF in the afterglow plasma. The magnitude T_e does not vary significantly and is determined by the heating and cooling balance between the thermal electrons and fast electrons. These fast electrons arise from superelastic collisions of the thermal electrons with vibrationally excited molecules. The measurements of the EEDF were made at 100 μs intervals during the relaxation period which lasted about 500 μs after the discharge.

Exact wave solutions are constructed for a cylindrical cold plasma bounded by a dielectric, taking into account possible particle sources. It is shown that the volume waves can either be amplified or damped because of their density dependence, while the surface waves are unaffected by the source.

Collisionless drift waves and associated particle fluxes are investigated in nonuniform plasmas in the presence of stationary high-Z impurities or charged dust particulates.

The processes and properties of an arc discharge plasma with admixture of cluster ions are analyzed. Parameters of a xenon arc plasma at atmospheric pressures with an admixture of tungsten cluster ions, tungsten atoms and atomic ions are calculated for regimes when this plasma is an effective light source.

The character of the growth of inert gas clusters which are supported by interaction between nearest neighbors is considered. The bases of optimal structures are truncated octahedra whose 6 faces are squares and 8 faces are regular or almost regular hexagons. The nonregular part in the total cluster energy is estimated as ~10D (D is the binding energy of two neighboring atoms) and does not depend on cluster size. Within the framework of the behavior of cluster energetic parameters, the typical temperature of transition from clusters to bulk particles due to fluctuations of the cluster energy as a result of vibrations of its atoms is estimated. Real inert gas clusters become bulk particles at numbers of atoms n > 10⁴.

A theory of low temperature capacitance measurements on thin film amorphous silicon structures, like p-i Schottky diodes or p-i-n solar cells, is presented. As the interface effects and the glow discharge deposition process dramatically affect the intimate structure of thin film materials, the material properties of thin films are extremely different from the material properties of thick layers. The theory takes into account the effect of the finite dimensions of the semiconductor layers in order to explain the experimental results. A small signal approximation leads to a simple analytical expression of the capacitance which can be easily used for measurement fitting. An extensive analysis of parameter sensitivity is presented together with some examples of how experimental results can be interpreted. To date, low temperature capacitance measurements appear to be the first characterization technique of thin doped layers included in a thin film structure.

The nonlinear dynamics of a coherent interacting polariton-biexciton system in optically excited semiconductors is investigated. We consider the case when two macroscopically coherent modes - a lower branch polariton and a biexciton existing simultaneously in a direct-gap semiconductor. The conditions for exhibiting optical bistability in stationary regime are obtained. Numerical simulation for the nonlinear dynamics equations of the system is also carried out.

The electrical switching behaviour of CdTe_xS_1-x doped borosilicate glass was studied by determining the D.C. current-voltage characteristics using a current source.

The I-V characteristic is non-linear for high current density leading to deviation from Ohm's law. The experiment data have been analysed under the assumption that the increase of the glass conductivity is dominated by the Joule effect. The used theoretical model is in good agreement with the experimental results.

In this work we measure the spectra and the time decay of photoluminescence in the conjugated polymer PPV and PPP thin films on the quartz substrate. Also, we compare the photoluminescence of PPP films deposited onto quartz, ITO and Si substrate at the same conditions.

The equilibrium of a self-gravitating incompressible fluid with a magnetic field and large electrical conductivity is studied. The magnetic fields and fluid motions are assumed to have a symmetry about an axis. The basic magnetic field is assumed to consist of two parts, namely, poloidal and toroidal while the fluid motion is assumed to be purely rotational. An exact solution of the MHD equations for the above configuration is presented. This study presents a more general form for the poloidal magnetic field than that studied by Gokhale and Hiremath for their modelling of the steady part of the Sun's internal magnetic field.