| Summary: | 碩士 === 國立中正大學 === 機械工程系研究所 === 107 === In order to investigate the changes in the electrical and internal chemical properties of helium plasma, this study develops a one-dimensional plasma fluid model to investigate the electron density and electron temperature in electrical characteristic in atmospheric helium dielectric barrier discharge, including impact and mechanism. The chemical model of the helium plasma model includes elastic collisions, excitation, quenching, dissociation, dissociation, electron attachment and detachment of helium, and important chemical reactions such as Penning Ionization to generate electron ion pairs. The physical model of the gas plasma model contains continuous equations to analyze the changes of particles in space and time, and the Poisson equation to calculate the electric field distribution inside the plasma reactor, and predict the overall behavior of the plasma under interaction. The simulation results show that the peak current density per half period is 12.5 A/m^2 under the condition of 5.5 mm gap and the voltage of 5.0 kV. In the experiment, the peak current density is 15.1 A/m2 per half period. These two results are close. By simulating the chemical reaction mechanism of helium plasma, the ratio of internal charge is analyzed in space and time-averaged particle number density. It is found that electrons account for up to 96.4% and the average number density is up to 10^16 m^-3 in helium plasma. Secondly, the oxygen ion O2- accounts for about 2% and the average number density is as high as 10^14 m^-3. The top three high positive ions are O2+, He2+ and O4+, respectively, the ratio is as high as 61.9%, 14.1% and 23.1%, and the average number density varies between 1015 and 10^16 m^-3. The space-time analysis reveals the difference between the internal electric field and the negative half period. The peak value of the electric field is up to 1000 kV/m, and the peak of the negative half period is up to -800 kV/m. In fact, the peak value is only slightly lower than 8 eV, which is similar to the results of other research teams. Therefore, this model has certain reliability for the analysis of helium gas plasma.
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