Electromagnetic field in plasma flow of microwave plasmatron

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.