Peculiarities of the formation of a filamentary structure of a microwave discharge in an argon flow

This paper presents the results of an experimental study of the spatial structure of a microwave discharge maintained in an argon flow by gyrotron radiation in a continuous mode with a frequency of 24 GHz at atmospheric pressure. In the structure of the plasma plume, stationary filamentary channels are observed, elongated along the direction of the argon flow, regardless of the orientation of the external electric field of the wave, surrounded by a diffusion halo. Measurements of the electron density, vibrational and rotational temperatures of gas molecules in plasma filaments have been carried out. The role of gas-dynamic mechanisms responsible for the formation of the inhomogeneous static structure of the plasma torch and the maintenance of a substantially nonequilibrium distribution of temperature characteristics in the discharge is discussed.