Plasma bubbles on langmuir probe in inductively coupled plasma

Abstract

Radio frequency created plasma is very promising for applications targets. Capacitively coupled plasmas is relatively well investigated (see e. g. [ID. Recently inductively coupled plasmas have foundm increasing interest due to their possible use for implantation [2] and etching devises [3]. In well progress are both the theory and the experiment of inductively coupled plasma, created by spud coil. There is only few experiments with helical coil among which in Frankfirrt Pm experiment [2]. Doing plasma measurements we surprisingly have encountered light bubbles at high current probe regime. The bubbles are due to two double layers. Double layers appear in thermionic emission devices or in such, “where a potential is applied between independently generated discharges, which are separated by grids” [6]. In our experiments there are neither thermionic emission, nor grids. The plasma bubbles have been observed experimentally on the probe in inductively coupled plasma, created by helical coil around the plasma source. The bubbles are the saturation stage of the Bunemann instability j4.51. At the appearance of the bubbles there is a jump of the current, which is accompanied by drastically drop of plasma resistant. A typical for double laym dynamics has been observed. This work has been supported by DAAD and grant F-408 of the Bulgarian National Fund for Scientific Research.