PL
EN

Volume 112 (2003)

CONTENTS

No. 112, 2003, 125-137

Plasma parameters in a surface wave discharge in nitrogen at atmospheric pressure
HELENA NOWAKOWSKA JERZY STAŃCO, ZENON ZAKRZEWSKI

Abstract

Spatial distributions of plasma parameters are calculated for a surface wave discharge sustained in nitrogen at atmospheric pressure. A macroscopic model, applicable to an axially uniform two-temperature plasma, yielcls the radial distribution, of the parameters. The axial distributions are determined from relations basecl on the approximation of local axial uniformity, which is valid provided the attenuation of the surface wave is weak. In the approxirnation adopted, the plasma panameters in any cross section of the discharge depend under given conditions solely on L, the power lost per unit length of the plasma column. Calculations made for a 2,45 GHz discharge in a capillary tube show an almost linear decrease of L ancl of the electron density towards the end ot thę discharge. The electron temperature for nitrogen is lower than for argon under similar discharge conditions. In nitrogen the electron density is about one order of magnitude lower and the gas temperature is much closer to the electron temperature than for argon. This may be explained by the presence of vibrational and rotational excitation ancl relaxation channels, which facilitate redistribution of the energy deposited in the discharge.

Keywords:

Surface wave, Microwave discharge, Plasma
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