[en] The measurements of a resistance and capacitance of the capacitor between plates of which plasma of a positive column of a discharge in argon is placed has been made in the KHz range. It has been found that the dependence of the plasma capacitor parameters on frequency is well explained if to represent a wall sheath in the form of the capacitance Csub(sh) shunted by the resistance Rsub(sh) which depend on the electron density on the sheath-plasma boundary and the electron temperature. Thus, the measuring of the impedance of the plasma capacitor gives a diagnostic means to determine the mentioned wall plasma parameters. (Auth.)

[en] Dust particles, immersed in a plasma, acquire charge due to which they may be electrostatically trapped in a plasma. The energy of the interaction of the dust particles may be enough to transfer the dust component to nonideal and even crystalline state. This phenomenon is observed in various plasmas. In the present work a review of the investigations of strongly nonideal dusty plasma of the dc glow discharge striations is given. The formation of plasma crystals, liquids and plasma liquid crystals is considered. Typical phenomenon a for the dc discharge dusty plasma, such as coexistence of different phases in a single structure, convective motions, dust acoustic instability, are underlined. Results of the experiments on different external influences on dusty plasma structures are stated. It is shown that external influences may be used for measuring of the particle charge and field of forces acting on a dust grain levitating in a plasma. (author)

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[en] Complete text of publication follows. Within researching processes of an appearance of ordered structures and phase transitions in nonideal dusty plasma the behavior of dust structures under the action of nanosecond electric pulses in the DC glow discharge has been studied. The search of resonance effects, stabilization, precipitation and destruction of dust structures is carried out. We performed experiments to study the action of nanosecond electric pulses with pulse repetition frequencies from 4 to 300 Hz. The analysis of a particle fluctuation amplitude has revealed the resonant frequency of 7.1 Hz (Fig. 1). The investigation of a mechanism of particle fluctuations was of great interest. It was revealed that nanosecond pulses change the background plasma near the particle and do not get an impact on the displacement of particles. In the previous experiments with the RF discharge a stabilization of particles was observed at the pulse repetition frequency of 16 Hz [1]. The similar experiment has been made in the DC glow discharge. The stabilization effect of self-excited fluctuations and waves was observed at a pulse repetition frequency of 200 Hz. Such behavior of particles is due to that an application of the capacitor nanosecond discharge forms an additional local ionization of plasma and artificial striation in which the dust cloud is stabilized. The further increase of nanosecond pulses frequency caused the effect of the dusty crystal melting and subsequently a precipitation of particles. We found experimentally that when a dusty cloud contains particles of two sizes it is possible to separate a heavier fraction by the partial trap destruction.

[en] A spontaneous excitation of a grain density wave in a dusty cloud of monodisperse particles suspended at the diffuse edge of an rf inductive gas discharge has been discovered. The main physical parameters of this wave (phase velocity, wavelength, and growth rate) and of the background plasma (distributions of the electron density, electron temperature, and space potential) were measured. A theoretical model of the observable phenomenon based on the theory of dust acoustic waves in a collisional dusty plasma correlates well with the experimental data in a broad range of experimental conditions. The influence of a varying dust grain charge on the development of the observed dusty plasma instability has been analyzed. It is shown that the necessary condition for the instability excitation is the availability of a permanent electrical field (E₀ ≥3 V/cm) in the dusty cloud region

[en] The spontaneous excitation of low-frequency oscillations of the macroparticle density in ordered dust structures levitating in standing striations of a dc glow discharge is discovered. It is concluded on the basis of a simplified linear model of an ideal collisionless plasma that the observed instability is caused by the drift motion of ions relative to the dust, which leads to the excitation of dust acoustic oscillations of the plasma

[en] Experiments on different external influences on the dusty plasma structures in the dc glow discharge are presented. The possibility of their application for diagnostic purposes is shown. Gas dynamic influence on the dusty plasma structures was considered for the first time. It was used for the excitation of nonlinear dust acoustic waves