Self-organization of surface wave sustained discharges in the pressure range from 10 to 200 Torr

Experiments showing the dynamics in the self-organization of surface wave s ustained discharges are presented. Microwave (2.4 GHz) discharges maintaine d in an argon gas in a continuous wave regime at a constant applied power a nd varying gas pressure are studied. The evolution of the discharge from a stationary plasma column at comparatively low pressure (p less than or equa l to 10 Torr) to a plasma torch at atmospheric pressure passes through diff erent stages of self-organization of the wave-field<->plasma nonlinear stru cture showing evidence of the general trends of behavior of nonequilibrium dissipative systems. The measurements are carried out at the stage of the d ischarge self-organization into a filamentary structure with an azimuthal r otation. Macroscopic characteristics (number, size, velocity of rotation) o f the filaments and their dependence on the gas pressure and its time varia tion 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 analysis) are applied. Os cillations of the filament ends are also observed. The different types of i nterrelation 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 th e discussions, the observations are important with their relation to the di scharge applications, which require avoiding conditions of development of i nstabilities. (C) 1999 American Institute of Physics. [S0021-8979(99)06312- 4].