O. A. Suvorova

A spherical microwave discharge induced at atmospheric pressure

A discharge induced at the end of an antenna in a flow of argon outgoing into the free space in a coaxial microwave plasmatron is described. Increased energy density supplied to the plasma leads to structuring of the microwave discharge. Effects of the antenna geometry, supplied power, and argon flow rate on the discharge structure are studied.

The Method of Electromagnetic Field Visualization with a Vibrating String

A new method of vibrating string is proposed for measuring the electric component of electromagnetic field. Actually, it is a variation of small probe method, used widely for analyzing the field distribution in cavities. A thin steel string (dstrLtlambda, LstrGtlambda) is used as a probe. The signal scattered is proportional to the field at the string position. The string oscillations play two roles: they move the probe in the field and they allow to distinguish the useful signal from reflections from static environment. Reliability and applicability of the method have been proved in the control measurements using the object with known field distribution.

Structure of a discharge induced by a coaxial microwave plasmatron with a gas-supply channel in the inner electrode

The structure of a discharge induced by a coaxial microwave plasmatron with a gas-supply channel in the inner electrode of a coaxial waveguide is investigated. A plasmatron with a power of up to 10 W operates at a frequency of 10 GHz. Depending on the operation regime, the discharge takes either a filament or torch form. A plasma filament arises at low flow rates of the working gas (argon) and occurs at the border of the potential core of the gas jet. A torch discharge occurs at high flow rates and has the form of a hollow cone. In both cases, the discharge arises in the potential core of the gas jet and does not spread beyond it. The distribution of the microwave field in the discharge plasma is determined.

Integrated electrodynamics characteristics of coaxial microwave plasmatron

The source of dense low-temperature plasma (plasmatron) is widely used in physical experiments and engineering. In this device, a cold working gas is blown through the discharge region The torch produces cold plasma. The structures and characteristics of plasma are determined by electrodynamics properties of plasmatron. The goal of this work is the investigation of plasmatron electrodynamic characteristics. Hence the electrodynamic characteristics of a coaxial microwave plasmatron operating at a frequency of 10 GHz are studied.

The electromagnetic field in the plasma jet of a microwave plasmatron

A coaxial microwave plasmatron operating at a frequency of 10 GHz is investigated. The microwave field distribution in the plasma jet of the plasmatron is studied using a vibrating string as a small perturbation source. The phase structure of the microwave field inside the plasma is found to differ from that on the outer side of the plasma jet boundary. A slow surface electromagnetic wave propagating along the plasma jet is observed.

Measuring of microwave fields in plasmatron flow

The paper deals with some electric field peculiarities in plasma flame of plasmatron. The method is based on the usage of vibrating string as a weakly perturbative body. The slow surface electromagnetic wave in plasma stream is found.

Electromagnetic field in plasma flow of microwave plasmatron

The paper deals with some electric field peculiarities in plasma flame of plasmatron. The method is based on the usage of a vibrating string as a weakly perturbative body. It is shown that the main portion of electromagnetic energy is consumed by plasma flame. The slow surface electromagnetic wave in plasma stream is found.A possibility of creating stationary stream of strongly nonequilibrium. (cold) plasma at atmospheric pressure by 10 GHz microwave oscillation source of continuous operation has been previously demonstrated. An electrodynamical structure of this plasmatron is waveguide-coaxial junction; plasma-forming gas (argon) is supplied through hollow inner coaxial conductor. Laminar plasma flame is formed in the plasmatron, and plasma run out into atmosphere. The plasma flame diameter does not exceed I mm, and its length up to 10 mm. It is significant that electric parameters of plasma in the microwave plasmatron satisfy the condition of surface electromagnetic waves propagation in plasma. High strength of electric field is assumed to exist in plasma, however until the present time any information about direct measurements of electromagnetic fields in such microwave plasmatrons was absent. Because of small dimensions of plasma as compared with wavelength, the electric field measurements are difficult to perform. Moreover, there are not so many techniques of microwave field investigation in free space, where microwave discharge takes place. Features and feeding scheme of plasmatron are described. Amplitude-phase distribution of microwave field along plasma flame axis obtained in several section of plasma is outlined.