I. B. Timofeev

Freely localized microwave discharge in a supersonic gas flow

A discharge produced by a focused microwave beam in a supersonic gas flow has been investigated experimentally. It is shown that the degree of ionization and the gas temperature in the discharge are fairly high and that the main properties of the discharge plasma are only slightly affected by the supersonic air flow. Discharges produced by focused microwave beams can find application in supersonic plasma aerodynamics.

Experimental investigations of the distribution of pulsed-plasma-generator radiation at its various spatial orientation and global anisotropy of space

Abstract Results of experimental investigation of plasma luminous emittance (integrated with respect to time and quartz transmission band spectrum) of a pulsed plasma generator depending on its axis spatial position, are presented. It is shown that the spatial distribution of plasma radiant intensity is of clearly anisotropic character, that is, there exists a cone of the plasma generator axial directions in which the radiation of plasma reaches its peak. A possible explanation of the results obtained based on a hypothesis of global anisotropy of space caused by the existence of a cosmological vectorial potential A g , is given. It is shown that the vector A g has the following coordinates in the second equatorial coordinate system: right ascension α=293°±10°, declination δ=36°±10°. The experimental results are in accordance with those of the earlier experiments on determining the direction of A g .

Influence of Surface Microwave Discharge on the Characteristics of Supersonic Flow near Streamlined Body

In the report physical processes which are taking place in the microwave discharge on external surfa ce of dielectric body being flown around of supersonic stream of air and in plasma of the volumetric freely localized microwave discharge were investigated. It is shown, that different types of microwave discharges can find application in aerodynamics for reduction of skin friction , for flow control and for plasma assisted combustion.

Transverse Electric Discharges in Supersonic Air Flows: Microscopic Characteristics of Discharge

The spectroscopic and probe methods are used to measure the microscopic parameters of plasma of pulsed and stationary transverse discharges in a supersonic air jet flowing into a submerged space. The measurements are performed for the Mach number of flow M = 2, submerged space pressure p = 5 to 30 kPa, degree of the jet being off-design n ∼ 2, and discharge current I = 1 to 10 A. The discharge current dependences of the average values of gas temperature, charged particle concentration, and reduced electric field are measured for a discharge mode close to that of current generator. The measured values of gas temperature lie in the range of 1 to 3 kK, those of charged particles concentration — of 1013 to 1014 cm-3 , and of reduced electric field — of 40 to 20 Td. The axial distribution of temperature is characterized by high values of temperature even at short distances from the electrodes and by a slow decrease along the flow.

Transverse Electric Discharges in Supersonic Air Flows: Space-Time Structure and Current-Voltage Characteristics of Discharge

The space-time evolution of potential distribution in a pulsed transverse discharge in a supersonic jet of air is studied in a mode close to the current generator mode. The current dependences of the longitudinal electric field intensity and of the discharge channel diameter are measured for different values of pressure in the jet. It is demonstrated that the electric field intensity decreases with increasing discharge current by the power law, with the exponent being close to that for a highly contracted glow or arc discharge in the absence of flow. The increase in current is accompanied first of all by an increase in the discharge channel cross section. The characteristics of the oscillatory mode of discharge burning are studied for discharge power supplies, which are close to the current generator mode. The obtained dependences of the oscillation period on the external parameters of discharge, namely, current, pressure, and interelectrode spacing, are interpreted. An expression is derived which describes the maximal extent of discharge along the flow in the case of instability due to external electric circuit. This extent may increase further only in the case of transition to supplies close to current generators; in this case, the extent is restricted by the mechanism of repeated breakdown.

Simulation of a DC Discharge in a Transverse Supersonic Gas Flow

AbstractThis study is devoted to the investigation of a dc discharge in a transverse gas flow. It is shown that the discharge may exist in several forms depending on the gas flow velocity. The standard stationary discharge similar to a discharge in still gas is realized if the displacement rate of the plasma boundary exceeds the gas flow velocity. The displacement rate of the plasma boundary in a diffusion model is defined by the relation Vf = 2

The interaction between plasma jet of a capillary discharge and transverse supersonic air flow

\sqrt {D_a v_i }

Experimental production of long-lived luminous organic polymeric objects

, where Da is the ambipolar diffusion coefficient, and νi is the frontal ionization frequency. Otherwise, the discharge assumes the form of two plasma wakes formed by the cathode and anode, respectively. The surface of the plasma wakes is oriented at an angle α to the flow velocity Cs (sinα = Vf/Cs). If sinα is smaller than the ratio of the discharge sustaining voltage in the stationary regime Ust to the breakdown voltage Ubk, the discharge transforms into the pulse–periodic form, when the formation of a structure of the cathode and anode plasma wakes is interrupted by a new gas breakdown. A numerical simulation of the discharge properties is performed. The numerical simulation results are compared to the experimental ones.