الفهرس 
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Abstract
This work consider the glow discharge mainly the plasma phenomena in the positive column region. We’ll use both theoretical and experimental analysis in our study. The properties of the plasma are measured using single and double langmiur probes. From the obtained data experimentally the electrons density is found to increase with the increasing of the discharge pressure and the electrons temperature is increasing with the discharge voltage but decreasing with the increasing of the pressure .
For the same gas and tube dimensions, the minimum discharge voltage necessary for self-maintained discharge is increasing with the pressure increase up to certain limit then it decreases The sheath phenomena is also studied. The distribution of voltage ~n the sheath is obtained theoretically by a model also the effect of the electrons secondary emission is taken into consideration through the sheath study.
The radial variation of the electron density in the glow discharge is obtained theoretically using a computer model for the positive column region. The same radial variation of the electrons density and temperature are measured experimentally using the double movable probe.
The two results are very close to each other. The energy balance is found for the glow discharge at constant neutral atoms density and applied discharge voltage. A semi¬experimental technic is used to find the level of the ion fluctuations in the glow discharge that is found to be in the range of 0.05 of the total energy.