Plasma of capillary discharge of low pressure

Ionization equilibrium is considered for a capillary plasma of low pressure within a scheme where a tail of the energy distribution function of electrons at energies above the atom excitation energy includes a small portion of electrons. The kinetics of a gas discharge plasma in strong fields is developed and allows one to determine the drift velocity of electrons and other parameters of a capillary plasma. The results are applied to a capillary plasma of helium and argon. The analysis leads to the optimal shape of the gas discharge chamber for the formation of a plasma torch with fast electrons

Stability of the cathode layer of normal glow discharge in argon

The conditions of stability of the cathode layer for the normal regime of glow discharge are considered within the framework of the classical theory of the cathode layer where the requirement of a certain current radius is reduced to a force which acts on the ions of the cathode plasma. The specific force on ions is evaluated from the condition of the cathode voltage minimum. It is shown that stepwise ionization is absent in the cathode region of normal glow discharge

Permeability of porous materials for liquid and gases

It is shown that propagation of liquids and gases through a porous material has a different character, namely, the viscosity characterizes this process for liquids, whereas for gases it is determined by collisions of the gas molecules with the skeleton of the porous material. The analog of the Kozeny-Carman formula in liquids for the Darcy coefficient or the permeability coefficient is represented for gases. The transition between these limiting cases results from the relation between the mean free path of an individual molecule in a liquid or gas λ and the mean free path of this molecule with respect to its scattering on the skeleton of a porous material

Development of ionization waves in argon at atmospheric pressure with inhomogeneous preliminary ionization

Experimental and theoretical investigations of the initial stage of the formation of a pulsed volume discharge between two plane electrodes in argon at atmospheric pressure under conditions of inhomogeneous preionization are reported. The experimental results of the propagation velocity of an ionization wave are compared with the obtained value from the numerical simulation. The features of the development of ionization waves in atmospheric-pressure argon are studied

One more study of argon arc binding to pure tungsten cathode

Pyrometric and spectroscopic investigations of pure tungsten cathode in argon arc plasma discharge at atmospheric pressure are reported. The distribution of surface cathode temperature and the radial distribution of plasma temperature at different distance from the cathode tip were measured. We conducted a comparison between our work and other studies on arc discharges where cathodes from lanthanated (W-2% La2O3) and thoriated (W-2% ThO2) tungsten were used

Analysis of processes leading to explosive phenomena on the surface of a liquid cathode at the time of the dc electric arc ignition

The paper considers various causes of explosions on the cathodes surface in the region of arc attachment in a direct current arc discharge. Estimates of the characteristic times of the development of instabilities during the passage of current through the liquid tip of the cathode are made. As a result, an assumption was put forward that, starting from the moment of formation of the stretched tip and up to the explosion, at different stages of the stretches development, various instabilities alternately play the main roles

Investigation of the argon arc binding to the lanthanated tungsten cathode

Pyrometric and spectroscopic investigations of lanthanated tungsten cathode in argon arc plasma discharge at atmospheric pressure are reported. The distribution of the surface cathode temperature was measured. Calculations and estimates of the emission current density are performed. Experimental data of the total current density are compared with the obtained results of estimation. The possible reasons for the discrepancy between the experimental and theoretical values of the total current were discussed

Mechanism of mass expulsion from the surface of a pure tungsten cathode during dc arc initiation

In this work the destruction mechanism of a pure tungsten cathode during the initiation of direct current arc is studied. The experimental work shows that the cathode resides in liquid form during the initiation of the arc, and the process of its destruction happens by ejecting droplets from its surface with the following explosion. The average speed of the ejection and the temperature at the explosion points microseconds before the explosion were registered. A mathematical model is proposed explaining the reason behind the droplets formation

The bubble method of water purification

The processes of water purification from admixture molecules are analyzed. The purification rate is limited due to a low diffusion coefficient of the admixture molecules in water. At non-small concentrations of the admixture molecules, the water purication can proceed through association of molecules in condensed nanoparticles which fall on the bottom of the water volume. The rate of association may be increased in an external electric field, but in reality this cannot change significantly the rate of the purification process. The bubble method of water purification is considered, where air bubbles formed at the bottom of the water volume, transfer admixture molecules to the interface. This method allows one to clean small water volumes fast. This mechanism of water purification is realized experimentally and exhibits the promises of the bubble purification method

Features of the cathode plasma formation at the initial stage of a nanosecond spark discharge in air

Nanosecond discharges at atmospheric pressure have a wide range of applications. The features of a nanosecond spark discharge formation strongly depend on the discharge gap geometry and the applied voltage. The present paper contains the results of near-electrode processes investigation at the initial stage of a spark discharge in air in the pin-to-plate geometry. Extra-high electron concentration in the range of $10^{19}\text{--}10^{20}\ \text{cm}^{-3}$ was obtained based on the Mach-Zehnder interferometer after breakdown near the surface of a flat cathode. It is confirmed that the discharge channel is a multitude of microchannels that close the discharge gap. Analysis of a flat electrode surface after breakdown shows that the channel binding region is a cluster of microcraters with diameter from 5 to $35\ \mu \text{m}$ . A model for the gas dynamics processes at the initial stage of a nanosecond spark discharge is proposed