Emission Spectroscopy Methodology For Low Temperature Discharge Plasma Of Low Pressure Gas

Emission Spectroscopy Methodology for Low Temperature Discharge Plasma of Low Pressure GasLow pressure gas discharge has been frequently utilized to generate plasma in laboratory and application. This kind of discharge is capable of providing various kinds of plasma for any requirements and realizing control of plasma parameters. There have been many kinds of gas discharge to generate plasma in a very wide scope of parameters. Discharges maintained with different parameters present different physical chemistry and therefore obeys different laws when they react with other status of mater. Low pressure discharge can be divided into DC discharge; AC discharge; HF (High Frequency) discharge and microwave discharge when the discharge is excited by different power sources. In recent years, many novel discharge schemes are invented, such as electron beam ionization; ion beam ionization; laser breakdown and inhomogeneous phase discharge. No matter how different the discharge scheme is, low pressure discharge plasmas take a common characteristic of bright glow and is generally entitled as low temperature glow discharge. Glow discharge plasma has been selected as a most suitable system for plasma diagnostics in laboratory and for application technology development because of its good stability and reproducibility. Its macro and microscopic properties and the physical-chemistry processes occurring in plasma systems are the focuses of plasma diagnostics, because reliable measurement of plasma parameters and accurate understanding of the mechanism of plasma processes are not only the principal promotion for the development of plasma physics but also the necessary preconditions for the realization of plasma technologies.One of the focuses of this dissertation is to describe the emission optical spectroscopy of low pressure discharge plasmas and presents the laws observed by the corresponding processes in the plasmas. Some diagnostic methods based on plasma static-electricity and spectroscopy are theoretically outlined at first, and then some investigations are theoretically made on the applicability of the diagnostic methods. As results of the investigations, some improvements of theAbstractsprinciples of diagnostics have been achieved and some new analytical methods are derived for the design of diagnostic tools and the extraction of more accurate information. Experimental measurements have also made on some novel and typical phenomena occurred in low pressure discharges to diagnose the mechanisms of these phenomena with help of some different methods and the newly developed analytical algorithms.Plasma system contains a very large amount of charged partials and hence static-electrical field always exists with plasma .The static-electricity of a plasma system is the most basic property and also the base of the other plasma processes. Because the charged particles in plasma move all the time and the plasma also contains a large mount of energetic species, such as excited states and radicals, radiation and optical emission is another principal property of plasma. Therefore, the diagnostics of electrical and optical characteristic of plasma form the basic respects of plasma diagnostics.The author reports in detail in the dissertation the experimental investigation on the phenomena of some common discharge systems at typical operation status such as DC glow; RF (Radio Frequency) glow and microwave ECR (Electron Cyclotron Resonance) discharge. The influences of discharge pressure and voltage on the discharge mode are studied in N2 DC and RF glow discharge. RF discharge under low pressure takes the similar breakdown mechanism with DC glow discharge, but the spatial distribution of optical emission spectra from RF glow is very different from that of DC glow discharge. It is contributed to the different optical emission kinetics between RF glow and DC glow systems. Numerical simulations on the both glow scheme are done using collision radiation kinetic model together with Prof. Bogearts of Belgium. Microwave ECR...