Magnetic re-entrance in intermediate valence compounds

We explore the possibility of magnetic re-entrance in intermediate valence compounds. Using a simplified Anderson-Lattice model we obtain the pressure-temperature magnetic phase diagram. This diagram shows that for some value of the microscopic parameters the temperature induced two transitions (non-magnetic to magnetically ordered to paramagnetic).We calculate the magnetization and the average occupation number of the localized state. Estimations of the observability of the effect in systems like CeAl₂ are made.     

On the motion of a particle with anisotropic mass

On the basis of the hypothesis that particle mass is anisotropic rather than isotropic, we investigate the relativistic motion of a particle within the framework of flat space-time. Assuming that the mass anisotropy is associated with the photon cloud of the particle, we argue that the self-energy of a particle is of the order of magnitude |δ m/M ₀|?0.0005, for which conventional quantum electrodynamics, however, gives an infinite value.     

On the feasibility of the coulomb explosion of a metal

The mechanism of the Coulomb explosion of a metal in an external pulsed electric field is discussed. In the case of a low-frequency field, when its frequency is lower than the frequency of electron collisions, it is impossible to reach the conditions of the Coulomb explosion of a metal if the field pulse duration is shorter than the time of electron energy relaxation upon elastic collisions, and the electron temperature is well above the Fermi energy and the work function. In the case of a high-frequency field, e.g., in a powerful pulse of ultraviolet laser radiation, the Coulomb explosion can occur if the field strength is well above the intraatomic field strength (i.e., when the laser power density is ≥10¹⁹ W/cm²).     

On the feasibility of observing electron antibunching in a field-emission beam

In contrast to the belief that low degeneracy and short coherence time prevent the direct observation of fermion anticorrelation in a free particle beam, it is shown that the antibunching of electrons in a field-emission electron beam should, in principle, be observable with current technology. This opens a gateway to fundamentally new tests of quantum mechanics.     

On the feasibility of normal wave selection in a shallow-water waveguide

Long-range propagation of low-frequency narrowband sound signals in the near-bottom acoustic channel with random inhomogeneities caused by internal waves and a rough bottom is investigated in the framework of numerical and field experiments. The feasibility of selecting the signal components corresponding to different normal waves is analyzed. The problem of selecting such components is considered for signals of long duration exceeding the characteristic time of the stationary state of the channel.     

On the anisotropic Heisenberg chain

High-temperature expansions are derived for the specific heat and the _χzz element of the susceptibility tensor for a linear chain of spins $\text{1}\text{2}$ with anisotropic nearest-neighbour interactions. (The coupling constants J₁, J₂ and J₃ are chosen to be different.) Use is made of exact results of the XY model, a first-order perturbation calculation in J₃, a high-temperature expansion for the transverse susceptibility _χxx of the anisotropic XY model and the high-temperature expansion for the isotropic Heisenberg chain. Some characteristic features of deviations from the case of axial symmetry in the coupling constants are discussed.     

On the feasibility of a parametric generator of hyperbolic chaos

A chaos generator consisting of two subsystems is considered. Each subsystem is a pair of parametrically coupled oscillators whose free-running frequencies differ by a factor of two. The subsystems are alternately driven by the third harmonic of a basic frequency, and energy is transferred between them through signal squarers. Based on a qualitative analysis and numerical results, a hypothesis is put forward that the system implements a hyperbolic strange attractor.     

On the line-width in critical anisotropic antiferromagnets

We present a calculation of the longitudinal scaling function for the line-width of critical uniaxial antiferromagnets. The agreement with experimental results for MnF₂ is satisfactory.     

On the relaxation of anisotropic plasmas

The relaxation of anisotropic plasmas due to collisions between two kinds of particles is discussed on the basis of the Fokker-Planck equation, i.e. collective interactions are not taken into account. An initially elliptic distribution is assumed to remain elliptic during the relaxation process. This is the only approximation made, i.e. the usual restriction to small anisotropy is avoided.     

On the feasibility of a plasma-chemical reactor for hydrogen production

It is proposed that a high-frequency discharge in humid air be used as a model of a plasma-chemical reactor for hydrogen production.     

On the feasibility of a fiber-based inertial fusion laser driver

One critical issue for the realization of Inertial Fusion Energy (IFE) power plants is the driver efficiency. High driver efficiency will greatly relax the driver energy requested to produce a fusion gain, resulting in more compact and less costly facilities. Among lasers, systems based on guided wave such as diode pumped Yb:glass fiber-amplifiers with a demonstrated overall efficiency close to 70% as opposed to few percents for systems based on free propagation, offer some intriguing opportunities. Guided optics provides the enormous advantage to directly benefit from the telecommunication industry where components are made cheap, rugged, well tested, environmentally stable, with lifetimes measured in tens of years and compatible with massive manufacturing.In this paper, we are studying the possibility to design a laser driver solely based on guided wave optics. We call this concept FAN for Fiber Amplification Network. It represents a profound departure from already proposed laser drivers all based on free propagation optics. The system will use a large number of identical fibers to combines long (ns) and short (ps) pulses that are needed for the fast ignition scheme. Technical details are discussed relative to fiber type, pump, phasing, pulse shaping and timing as well as fiber distribution around the chamber. The proposed fiber driver provides maximum and independent control on the wavefront, pulse duration, pulse shape, timing, making possible reaching the highest gain. The massive manufacturing will be amenable to a cheaper facility with an easy upkeep.     

Temperature dependence of spin-hamiltonian parameters for chromium doped rutile

The temperature dependence of the spin-Hamiltonian parameters for substitutional Cr³⁺-ions in single crystal rutile (TiO₂) has been studied. The measurements were performed at about 9·2 GHz and 35 GHz on a fine powder of single crystalline Cr-TiO₂ for three temperatures, 95, 200, and 295°K. It was found that the spin-Hamiltonian parameter D diminishes with decreasing temperature in the temperature interval studied. The behaviour of g and E is more complex. A tentative extrapolation of the data towards 0°K has been made.     

On the feasibility of charged wormholes

While wormhole spacetimes are predictions of the general theory of relativity, specific solutions may not be compatible with quantum field theory. This paper modifies the charged wormhole model of Kim and Lee with the aim of satisfying an extended version of a quantum inequality due to Ford and Roman. The modified metric may be viewed as a solution of the Einstein fields equations representing a charged wormhole that is compatible with quantum field theory.     

On stationary topological solitons in a two-dimensional anisotropic Heisenberg model

We study stationary two-dimensional solitons in an easy-axis Heisenberg magnet with the Hamiltonian density wherei=1, 2,a=1, 2, 3, and (x _i ) is the angle between unit vector s(x _i ) and the easy axis, 0<p<. Stable solitons with a topological chargeQ=1 and localized distributionss ^a (x _i ) withQ=2 are found. The existence of the bound states of two solitons withQ=1 is shown numerically for 0<p<.     

On the initial singularity in the scalar-tensor anisotropic cosmology

In connection with the problem of the initial singularity in the scalar-tensor anisotropic cosmology of Jordan-Brans-Dicke, the dynamics of homogeneous models of Bianchi type I is examined on the basis of the general analytic solutions in vacuo and in the presence of gravitating matter with state equations P=n? (0 ? n ? 1). It is shown that the scalar homogeneous ?-field, as an effective source of the V₄geometry, has to influence essentially the dynamics of the early anisotropic stage of the Universe's expansion, and significantly modifies the character of the initial singularity. At negative ω (ω < ?6), the sourceless scalar ?-field may remove the singularity and provide regular ‘bouncing’ in the models with matter (P ? ?/3) if it prevails over the tensor anisotropic mode of the vacuum gravitational field.     

On the feasibility of an EMP laser

Intrinsic semiconductor samples in crossed electric and magnetic fields emit under certain conditions recombination radiation (EMP effect). Conditions are formulated under which this effect can be utilized for a laser. Semiconductors with high mobilities, high intrinsic concentration, high volume lifetime, and small effective masses are required. An EMP laser made of InSb appears to be feasible.