Electrohydrodynamic monodispersion of liquids

In electrostatic dispersion of a liquid from a meniscus at the end of a capillary through which the liquid is passed the emitted droplets are unstable with respect to their self-charge and break up, ejecting about 100 smaller (by two orders of magnitude) droplets. However, if the liquid is passed through the capillary under pressure, then, depending on the pressure, there exist ranges of values of voltages applied to the electrodes for which the emitted droplets are stable both with respect to their self-charge and with respect to the external electric field of the system of electrodes. In this paper, the sizes, charges, and specific charges of such droplets are calculated on the basis of the principle of least dissipation of the energy.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 32–40, March–April, 1991.     

Transition from pushed-to-pulled fronts in piecewise linear reaction–diffusion systems

The front dynamics in reaction–diffusion equations with a piecewise linear reaction term is studied. A transition from pushed-to-pulled fronts when they propagate into the unstable state is found using a variational principle. This transition occurs for a critical value of the discontinuity position in the reaction function. In particular, we study how the transition depends on the properties of the reaction term and on the delay time. Our results are in good agreement with the numerical solutions of the model.     

Characteristics of pulsed discharges in copper bromide and copperHyBrID lasers

Comparative measurements of discharge electrical waveforms have been carried out with a Ne-H₂-CuBr laser, a Ne-CuBr laser, and a Cu HyBrID laser, each of the same size and geometry, and under the same conditions of excitation. From the general similarity of the electrical characteristics of the HyBrID laser and the Ne-H₂-CuBr laser, together with a reappraisal of the role of hydrogen, it is concluded that the main characteristics of these lasers (high efficiency, high average output power, and special features of their excitation pulse waveforms) can all be qualitatively explained if we assume that HBr and not hydrogen (molecular, atomic, or ionic) is the responsible agent which acts via the process of dissociative attachment of electrons to HBr during the interpulse period and during the early stages of the discharge current pulse     

Dissipative structure in interplanetary plasma

Dissipative structures in hot interplanetary plasma are considered, which are formed due to a resonance interaction of long-wave longitudinal perturbations with nonlinear Alfven waves propagating along the magnetic field. The form of the structures is found by averaging known solutions of the derivative Schrodinger equation over the fast field phase. It is established that the dissipative structures are shaped as smooth parts of the envelope of the magnetic field, and that they are shock wave trains separated by rotational discontinuities. An equation is found which describes the structure of rotational discontinuities, and a simple step-like solution is found which fits well the obtained structures. These solutions agree with observations of rotational discontinuities in interplanetary plasma.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 104–108, August, 1991.     

On modulation instability of nonlinear Alfven waves

The modulation instability of nonlinear Alfven waves in high-temperature plasma with _{e i} = 1 with allowance for resonance particles is discussed. A dispersion equation is derived for longitudinal perturbations and instability increments in regions æ << æ ₀ ^* , æ >> æ ₀ ^* , and æ æ ₀ ^* . For short-wave perturbations æ >> æ ₀ ^* , the dispersion equation leads to the well-known formula for the Landau coefficient of nonlinear decay. As an example of application of the obtained formulas, the correlation and cross-correlation functions are calculated for perturbations of the transverse magnetic-field component of nonlinear Alfven waves propagated along the magnetic field.Chechno-Ingushskii State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 8, pp. 663–670, August, 1992.