A theory of ion-guided and metastable-guided varieties of ionization waves (striations)

The well-known two varieties p and r of ionization waves (striations) in neon are explained as ion-guided and metastable-guided ionization waves with essentially identical propagation mechanism. To obtain both waves as a solution, in the basic system of equations the time-derivatives in the continuity equations for both the ions as well as the metastables are taken into account. At low discharge currents, the rate of change of the metastables is slower than the rate of change of ion density, and both wave varieties develop separately and can exist simultaneously.The hydrodynamic equations are used for the formulation of the theory and the electron energy distribution is characterised by the mean energy. The Druyvesteyn distribution for electrons (instead of the usually used Maxwellian distribution) is used for calculation of the transport coefficients of the electron gas at the low currents, while the dependence of ionization and excitation rates on the mean electron energy is chosen by trial only and fitted to experimental characteristics of the waves. With non-maxwellian transport coefficients, an instability of the ion-guided wave occurs without any influence of stepwise ionization.The authors are deeply indebted to V. Krejí and O. tirand for their valuable remarks, and also T. Rika for providing his recent results and for enlightening discussion.     

Existence and nonexistence of traveling waves and reaction-diffusion front propagation in periodic media

We review the existence results of traveling wave solutions to the reaction-diffusion equations with periodic diffusion (convection) coefficients and combustion (bistable) nonlinearities. We prove that whenever traveling waves exist, the solutions of the initial value problem with either frontlike or pulselike data propagate with the constant effective speeds of traveling waves in all suitable directions. In the case of bistable nonlinearity and one space dimension, we give an example of nonexistence of traveling waves which causes quenching (localization) of wavefront propagation. Quenching (localization) only occurs when the variations of the media from their constant mean values are large enough. Our related numerical results also provide evidence for this phenomenon in the parameter regimes not covered by the analytical example. Finally, we comment on the role of the effective wave speeds in determining the effective wavefront equation (Hamilton-Jacobi equation) of the reactiondiffusion equations under the small-diffusion, fast-reaction limit with a formal geometric optics expansion.     

Plasma instability in a strong,circularly polarized electromagnetic wave

Conclusions In summary, we have studied the parametric instability of a cold electron plasma in a strong, circularly polarized electromagnetic wave, taking into account the relativistic nature of the electron motion. We have shown that an instability of longitudinal waves occurs at frequencies _p/ and _p/, while an instability of transverse waves occurs at frequencies ₀±₀ and ₀±_p/. The results of a numerical solution of the dispersion relation for large pump amplitudes, in which case the approximation of a weak coupling between waves is not applicable, show that the growth rates and the bands of the instabilities increase with increasing pump amplitude. We have found that in the case of the excitation of electromagnetic plasma waves, even at low pump amplitudes, the relativistic nature of the electron motion can be of decisive importance for the effect.T. G. Shevchenko Kiev State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 19, No. 10, pp. 1481–1488, October, 1976.     

Resonance Selective Excitation of Terahertz Plasma Waves in a Semiconductor Quantum Well Using Two-Color Laser Radiation

A new method of coherent resonance excitation of plasma instability in a 2D quantum well driven by twocolor laser radiation due to photoinduced generation of electron–hole pairs is proposed. It is shown that under the resonance condition, where the frequency and wavenumber of the beat wave obey the 2D plasmon dispersion relation, a spacecharge wave is excited efficiently. A selfconsistent treatment of the problem is presented and the smallsignal response of the 2D system in the THz frequency region is found. This new method provides the selective resonance excitation of plasmons, tuning of their frequency, and efficient control of plasma wave parameters crucial for THz semiconductor technology.     

The role of the initial suppression of beam-plasma interaction for short experimental devices

Conditions for excitation of the h.f. beam-instability in a relatively short (L _b/) beam-plasma system have been studied. The beginning of the effective energy transfer from the beam electrons to the excited wave measured from the instant of their entrance into the system is delayed by a certain timet _crit that reaches its maximum valuet _crit3/2 for a monoenergetic beam. If waves with the group velocity comparable to that of the beam grow up to a measurable value only provided that the waves are effectively reflected on both ends of the system, the efficiency of the interaction is further lowered. The systematical change of the phase velocity of the excited wave leads to the interruption of the instability after a few such reflections. The theoretical results have been confirmed by the experimental measurements on the ELMAN II machine.It is a pleasure to acknowledge the permission to publish experimental results obtained by Dr. V. Piffl and Dr. J. Ullschmied.     

Response functions of free mass gravitational wave antennas

Rainer Weiss and collaborators have from first principles derived the response of a free mass interferometer (or 2-arm gravitational wave antenna) to plane polarized gravitational waves [1]. We here obtain equivalent formulas (generalized slightly to allow for arbitrary elliptical polarization) by a simple differencing of the 3-pulse Doppler response functions of two 1-arm antennas [2]. A 4-pulse response function is found, with quite complicated angular dependences for arbitrary incident polarization. The differencing method can as readily be used to write exact response functions (3n+1 pulse!) for antennas having multiple passes, or having more arms.The research described in this paper was carried out at the Jet Propulsion Laboratory, under contract with the National Aeronautics and Space Administration.     

On the strength of Einstein's unified field equations

Einstein's concept of the strength of a system of field equations, which has been related in a simple way to the amount of initial data required for the system, is examined for his last unified field theory. The apparently surprising weakness of this system is traced to the high order of the associated electromagnetic field equations. These equations allow the existence of purely electric longitudinal waves, in spite of the absence of any photon mass.     

Neutron diffraction studies of the premartensitic transformation B2 → B19′ in Ti49Ni51 single crystals

We have studied structural changes in the high-temperature B2-phase in a large single crystal at temperatures near the premartensitic transformation B2 B19. We are the first to observe an extra 1/2 (110) reflection in neutron diffraction patterns taken along the [110]_B2 direction as the sample is cooled below 420 K, but still far from the martensite start temperature (M_s=180 K). This extra reflection heralds the formation of long-range order in atomic displacements with wave vectorq=(1/2±)[110]2/a. Premartensitic diffraction effects (caused by the development and correlation of lattice waves of atomic displacements with wave vectorsq ₁2/a[1/3, 1/3, 0] andq ₁2/1[1/3, 1/3] that were clearly visible in this same single crystal before the martensitic transformation B2 R, appeared at even lower temperatures with substantially lower intensities.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 56–61, January, 1995.     

On “surface currents” of a tubular beam having helical electron trajectories in the field of a fast wave

The causes of the noncoincides of the results of the hydrodynamic and corpuscular methods of analyzing the interaction of a rotating electron beam in a fast wave, which have been presented in published papers, are investigated. Consideration of the pulsations of the beam boundaries in the hydrodynamic analysis by introducing equivalent surface currents leads to the relativistic dispersion equation derived by Gaponov [1] in the case of a small thickness of the beam walls.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 15, No. 1, pp. 136–143, January, 1972.     

Pressed waves: Surface-bulk electromagnetic eigenmodes of metal surface

We discovered that in the infrared in conditions of surface electromagnetic waves (SEW) excitiation on finite grating coupler a wave packet consisted of evanescent and bulk waves is generated. This wave packet is conventionally called pressed wave by us. The wave packet is demonstrated to satisfy Maxwell equations and boundary conditions on smooth part of a surface outside the grating coupler. Thus the wave packet is a new type of surface-bulk electro-magnetic eigenmodes of metal surface.     

Progressing waves on spherical spacetimes

A family of spherically symmetrical spacetimes that are transparent to minimally coupled scalar multipole waves is investigated. The concept of transparency is reformulated in terms of the established concept of progressing waves. The set of spherically symmetric spacetimes and the family of wave equations for which the transparency condition can be shown to hold is generalized.     

Static and Vibrational Properties of Transition Metals

A model pseudopotential depending on an effective core radius but otherwise parameter free is proposed to study the equation of state by incorporating the s-d hybridization effects. Very recently proposed screening function due to Sarkar et al has been used to obtain the screened form factor. The equations of state for Cu, Ta, Mo, W and Pt have been studied up to the pressure of 1000 GPa. The vibrational properties such as phonon dispersion curves (in q and r space), phonon density of states, mode Grüneisen parameters, maximum frequency _max, mean frequency , ^21/2 = (/ ^-1)^1/2 and fundamental frequency ² and static properties such as dynamical elastic constants of rhodium and iridium are also calculated. The theoretical results are compared with experimental findings wherever possible. A good agreement between theoretical investigations and experimental findings has confirmed our formulation.     

Interaction between the nucleon and muon currents in elastic neutrino-nucleon interactions

The spin relations of neutrino-nucleon interaction with the formation of a muonv(V) N N are investigated within the framework of the two-component and four-component theories of two neutrinos under the assumption of a point neutrino. The difference between the predictions of the two theories is identified. It is shown that the four-component theory of two neutrinos, unlike the two-component theory, accommodates the V + A variant of interaction between the muon current (v) and the barion current.The authors are grateful to Prof. A. A. Sokolov and to R. Sh. Yakh'yaev for evaluating the results.     

Nonstationary quantum mechanics. I. Time-irreversible noninstantaneous self-reduction to a stationary state of some quantal wave packets

It is shown that the formalism of quantum theory needs modification in the case of potential fields swiftly varying with time. The necessity of a time-irreversible master equation for such cases is discussed.The underlying idea is that any (sub)system will undergo a spontaneous transition to a state of definiteenergy in the process of separating spatially from the rest of the universe, assuming the universe is isolated and has a definite energy. This requires what might be termed a pragmatic interpretation of the wave function: If a composite, separated system is represented by a linear superposition of product states, we may say that the actual state of the composite system is represented by some particular component of the superpositionfor the purposes of statistical inferences relevant to each subsystem alone, but the entire superposition—and not the corresponding mixture of the product components—must be used to compute the statistics of correlations. The considerations are illustrated with thought experiments which are real enough to make the application of the usual quantum mechanical formalism possible. Cases of disagreement between conventional theory and experiment in the field of interest are indicated.     

Instead of particles and fields: A micro realistic quantum “smearon” theory

A fully micro realistic, propensity version of quantum theory is proposed, according to which fundamental physical entities—neither particles nor fields—have physical characteristics which determine probabilistically how they interact with one another (rather than with measuring instruments). The version of quantum smearon theory proposed here does not modify the equations of orthodox quantum theory: rather it gives a radically new interpretation to these equations. It is argued that (i) there are strong general reasons for preferrring quantum smearon theory to orthodox quantum theory; (ii) the proposed change in physical interpretation leads quantum smearon theory to make experimental predictions subtly different from those of orthodox quantum theory. Some possible crucial experiments are considered.     

РЕАКЦИЯ (γ, р) НА КОБАЛЬ ТЕ

- , Li(, ) ( =17,6. 14,8 MeV). , u . , gQ=0,74+-0,16 MeV ⁵⁸Fe E ^* : 6,76; 6,44; 5,90; 5,47; 4,98; 4,35; 3,50; 3,20 MeV. , .     

Geometry of dislocated de Broglie waves

The geometrical structures implicit in the de Broglie waves associated with a relativistic charged scalar quantum mechanical particle in an external field are analyzed by employing the ray concept of the causal interpretation. It is shown how an osculating Finslerian metric tensor, a torsion tensor, and a tetrad field define respectively the strain, the dislocation density, and the Burgers vector in the natural state of the wave, which is a non-Riemannian space of distant parallelism. A quantum torque determined by the quantum potential is introduced and the example of a screw dislocated wave is discussed.     

Segregation of Components as a Result of High‐Power Laser Irradiation of Heterogeneous Condensed Media

The effects of periodic segregation of components in metastable (supercooled or supersaturated) binary alloys in the course of kinetic phase transformations as a result of laser irradiation of heterogeneous systems were studied analytically. Nonlinear processes of temporal and spatial selforganization of concentrationrelated structures were simulated using (i) a selfconsistent system of timedependent twodimensional equations for the distribution function for the sizes and spatial coordinates of the newphase particles and (ii) balance equations for the temperature and concentration of dissolved components; the latter equations account for nonlinearity of the particlesource function, sinks, for dependences of the phasetransition temperature on the surface curvature of particles and on the concentration of components, and for diffusive motion of particles in space. The domain of existence for the instabilities under consideration and the characteristics of the formed crystallizationrelated periodic structures are determined. It is established that nanoclusters formed during supersaturation of crystallizing material may play an important role in generation of selfoscillatory crystallization modes. Hydrodynamic aspects of liquidphase concentrationrelated stratification in heterogeneous systems based on immiscible components are considered.     

Singularity and unanimity

Examples are adduced which lead one to ask if the following rule of unanimity makes sense: Given, a classical dynamical problem. Given, that all solutions of the equations of motion (a) run into a singularity [or (b) are free of singularity], except a set of measure zero. Then (rule of unanimity), all solutions of the corresponding quantum mechanical problem are (a) singular [or (b) free of singularity]. If valid, this rule would imply that quantization of Einstein's standard general relativity model for a closed universe gives no escape from the singularity of gravitational collapse.Dedicated to Achille Papapetrou on the occasion of his retirement.     

Interacting spinor and scalar fields: Exact self-consistent solutions in Bianci I space

Exact self-consistent solutions of the equations that describe a system of interacting spinor and massless scalar fields with the interaction Lagrangian L_int=_,^,(S), where (S) is an arbitrary function of the invariant S=, are obtained in Bianci I space. The possibility of excluding the initial singularity is studied for the case of a power-law function (S), and isotropic expansion of the space as t is established.Russian University of International Amity. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 53–58, July, 1995.