Experiments showing the dynamics in the self-organization of surface wave sustained discharges are presented. Microwave ͑2.4 GHz͒ discharges maintained in an argon gas in a continuous wave regime at a constant applied power and varying gas pressure are studied. The evolution of the discharge from a stationary plasma column at comparatively low pressure (pр10 Torr) to a plasma torch at atmospheric pressure passes through different stages of self-organization of the wave-field↔plasma nonlinear structure showing evidence of the general trends of behavior of nonequilibrium dissipative systems. The measurements are carried out at the stage of the discharge self-organization into a filamentary structure with an azimuthal rotation. Macroscopic characteristics ͑number, size, velocity of rotation͒ of the filaments and their dependence on the gas pressure and its time variation are given. The total light emission of the plasma considered as giving information about the plasma density is measured and different methods of signal processing ͑including correlation-spectrum analysis͒ are applied. Oscillations of the filament ends are also observed. The different types of interrelation between plasma density and field intensity, registrated in the different pressure ranges, call for variety in the instability mechanisms. Although the scenario of the discharge self-organization is stressed in the discussions, the observations are important with their relation to the discharge applications, which require avoiding conditions of development of instabilities.

Summary: Results from tandem‐type probe diagnostics of a plasma source based on an inductive discharge are presented in this study. The driver region is in the classical form of a cylindrically shaped inductive discharge, with a coil positioned over a gas discharge tube, whereas a bigger metal chamber provides volume for plasma expansion. Low pressure argon discharges were studied. The axial profiles of the plasma parameters were measured in the discharge in the metal chamber. The results obtained show that decreasing electron temperature and plasma density with increasing distance from the driver characterizes the behavior of the expanding plasmas. Moreover, two regions with different rates of variation of the plasma parameters complete the plasma expansion volume: a faster drop close to the driver and slow axial changes away from it. The gas pressure and power applied for the discharge maintenance were the external parameters varied.

No abstract

No abstract

No abstract