الفهرس 
Chapter 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
In this thesis experimental diagnostic techniques of plasma produced in a hollow cathode electrical gas discharge are reported and discussed. Two types of hollow cathode are specially designed and constructed in this work. A Micro-hollow cathode with 2mm-hole diameter and the other has a cylindrical shape with 48mm hole diameter. The first of these was used in the case of dc electrical gas discharge while the second was for the study of pulsed electric discharge.
The measurements were first devoted to the study of dc Micro-Hollow cathode discharge, and inparticular the glow region, where currents were varied between 0 and 10 mA.
The experiment was carried out for the case of Helium and dry air to determine the stable range (no arcing) of dc Micro-Hollow cathode Glow discharge.
The Results of this investigation showed the V-I characteristics of both He and dry air as a function of gas pressure. Moreover, The measurements of the spectral emissions from the plasma were carried out using two different techniques;
A CCD camera imaging system is used for the plasma plume intensity while an optical Multi-channel Analyzer (OMA) system is used for the spectral line intensity.
In these two techniques the effect of gas pressure and discharge current on the intensity were presented The results of dc Micro-hollow cathode glow discharge revealed that: in the case of He, the discharge was found to be stable over a pressure range (10 - 400 Torr) while for air this range was from (0.7 - 50 Torr). In addition for He, the discharge showed a positive resistance behavior, in particular at the region (10-50 Torr), but in case of air, a negative resistance behavior was observed in particular at high pressures rang (30 -50 Torr).
On the other hand CCD camera images plume clarified the hollow cathode effect where the change of the plasma plume size and intensity of different zones indicated the corresponding pressure at which a transition of the discharge from the cathode cavity (The inside walls of the cathode) to the inner part of the hollow cathode (the inside hole) take place.
The effect of increasing the discharge current showed that there was a consistency between the intensity of plasma plume and the discharge current.
An other behavior of the discharge was observed during the spectroscopic measurements of the spectral line intensity.
It was shown that the line intensity under goes a pronounced transition as the pressure increase above 1 Torr.
This transition was associated with an abrupt increase in its values inparticular for the lines (3926.53 A, 7065.71 A, 6678.15 A and 5875.7 A).
This increase was also observed when the discharge current was increased, but with gradual behavior in this case.
In an attempt to study the characteristics of the discharge with a pulsed hollow cathode discharge the measurements were carried out in the case of He to investigate the plasma parameters. In this case we limited our study first, to the effect of gas pressure on both the operating voltage and the spectral line intensity.
The results of the voltage pressure relation indicated that the discharge was operating on the left side of the minimum value of Paschen curve. On the other hand the line intensity curves showed a peak in the low-pressure region. In addition the variation of the line intensity with the discharge repetition rate showed a fast DROP in the intensity for all spectral lines (4437.55A, 4471.7 A, 5015.68 A, 5875.7 A, 6678.15 A, 7065.71 A) over the repetition rate region (0 - 5 HZ) beyond which an almost constant line intensity was observed up to 50 HZ.
Secondly, The study of the plasma plume imaging showed that at low pressure, the plasma plume intensity centered on the axis of the two electrodes with its distribution follows a Gaussain shape. As the gas pressure increases the intensity of the central part decreases with the appearance of two hubs in its distribution located near the two side ends of the distribution (near the wall).