Combined weak-current discharge in a copper-vapor laser

We have considered the application of a new method of pumping of active media on metal vapors by a combined weak-current discharge. A distinguishing feature of a weak-current discharge compared to the method for the traditional pumping of self-contained lasers is the regime of lower energy input to the discharge. Using this regime, it is possible to realize a pulsed-periodic form of the discharge with laser pulses of various shapes and durations at low current amplitudes (several amperes). Additional pulsed-periodic discharge is used to heat the active zone.     

Spectra and color centers of strontium titanate crystals

The results of studying the spectral properties of strontium titanate single crystals (grown under different conditions), both pure and activated by iron-group or lanthanide ions, are presented. The data on the main color centers and the formation of systems of ordered crystallites from 10⁻⁷ to 10⁻⁹ m in size on the sample surface after treatment in plasma are obtained by optical and X-ray spectroscopy, cathodoluminescence, electron microscopy, and atomic-force microscopy.     

Polariton spectrum of a bounded antiferromagnet with a center of antisymmetry in an external electric field oriented normally to the surface

The features of transmission of TE and TM polaritons through an interface between magnetic and nonmagnetic media and their localization at the interface in an external dc electric field have been studied. This field is directed along the hard magnetization axis. The magnetic medium is an easy-plane tetragonal antiferromagnet; it is odd with respect to inversion. A magnetic plate and a 1D magnetic photonic crystal in an external dc electric field, oriented normally to the interface, are considered.     

Experimental and theoretical study of the supporting power of longitudinally compressed slightly conical shells made of composite materials

Mechanics of Composite Materials -     

Nonlinear dynamics of a backward-wave tube under the condition of competition of two modes

We study the nonlinear dynamics of backward-wave tubes in the regime of interaction of an electron flux with two transverse modes. In the region where the threshold values of parameters are slightly exceeded, one can observe a stationary single-mode oscillation when the other mode is suppressed, which is in good agreement with experimental observations of the competition of two modes in the relativistic backward-wave tube. It is shown that nonlinear competition can lead to the establishment of a single-mode stochastic regime of oscillation in the wide range of parameters in which the conditions of stochastic self-modulation are fulfilled for each mode individually. This work was presented at the Summer Workshop “Dynamic Days” (Nizhny Novgorod, June 30–July 2, 1998). Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 12, pp. 1565–1571, December, 1998.     

Determination of Selenium(IV) by Stripping Voltammetry at a Mercury-Film Electrode

A procedure was proposed for the determination of selenium(IV) by stripping voltammetry on a mercury-film electrode at an electrolysis potential of +0.4 V versus the saturated silver–silver chloride reference electrode in a 1 M H₂SO₄ solution. The current of the cathodic peak is a linear function of the selenium(IV) concentration in the range from 5 × 10^–3 to 3 × 10^–1 mg/L (6.3 × 10^–8 to 3.8 × 10^–6 M) at a time of electrolysis of 30 s (t _el). The detection limit for selenium is 1 × 10^–4 mg/L (1.3 × 10^–9 M) at t _el = 300 s. It was shown that selenium(IV) can be determined in the presence of 10 mg/L Zn(II), 1 mg/L Cd(II), 0.5 mg/L Pb(II), and 0.2 mg/L Cu(II). A procedure for the determination of selenium in natural, mineral, and potable water was proposed.     

Dynamics of topological solitons in models with nonlocal interactions

A nondissipative generalization of the sine-Gordon equation to cases with nonlocal interactions is analyzed. A model of this sort is shown to describe signal propagation in a Josephson transmission line with a nonlocal inductive coupling. The incorporation of nonlocal interactions changes the properties of the model in a qualitative way, leading in particular to the appearance of some new soliton entities: 2kpi kinks, where k greater, similar 1. These entities do not arise in a local model. They are evolutionary, they interact with each other in a quasielastic fashion, and they can be generated in a corresponding transmission line.     

Surface dynamics of a nongyrotropic multiferroic with quadratic magnetoelectric interaction

The effect of quadratic magnetoelectric interaction on the conditions of propagation and localization of one-partial polariton and elastic surface waves has been studied by the example of a bounded centrosymmetric easy-axis ferroelectric antiferromagnet.     

Pulsed high-order volume mode gyroklystron

We present the results of studies of a gyroklystron with the TE₅₃ output mode. A 30-dB gain is obtained at a frequency of 30 GHz for an output power of 5 MW, efficiency 25%, pulse duration 0.4 ms, and amplification bandwidth 40 MHz.