Plasma parameters in noble-gas narrow-tube and capillary-tube discharge, positive column plasmas

The plasma parameters in noble-gas narrow-tube and capillary-tube plasmas have been studied experimentally over the pressure (p) range from 0.1 to 10 Torr. Tube inner diameters, 2R, of 0.5 and 0.8 mm (capillary) and 3 mm (narrow) were used in the present investigation, together with axially movable anodes and cylindrical electrostatic double probes for the electric field and the electron temperature measurements, respectively, in noble gases, i.e. He, Ne, Ar, Kr and Xe. The results show that the axial electric field E z /p and plasma density decrease with increasing pR and the atomic weight of noble gases. No significant tube radius effect has been observed for the axial electric field if one analyses results in terms of pR. The electron temperature decreases significantly with increasing pR for He and Ne, and depends slightly on pR for Ar, Xe, and Kr.