Theoretical Investigations Of Nanosecond Pulse Discharge Argon Plasma And The First Positive Band Of Electron Collision Excited Cross Sections For Nitrogen Molecules

Plasma is a collection which contains a number of positive and negative charged particles, and appears no net space charge. Plasma is called the fourth state of matter in the universe. In recent years, the plasma physics has developed very quickly, and is applied in the electric power industry, material processing and radio communication, and many fields, especially the magnetically confined plasma research on nuclear fusion reaction and energy problem provides an attractive prospect. Chemically reactive plasma discharges are widely used to modify the surface properties of materials. Plasma processing technology is vitally important to manufacturing industries, aerospace, biomedical, and toxic waste remedy industries. Therefore, further study on plasma discharge is indispensable. In this paper, the investigations are divided into two aspects:nanosecond pulse discharge Argon plasma simulation; calculations of electron collision excited cross sections for nitrogen the first positive band system.In recent years, the better understandings of nanosecond pulse discharge plasma are very useful to produce plasma with uniform, stable and high concentrations of abundant reactive species containing radicals, metastable species, ions, electrons and photons. The non-equilibrium plasma being apply to material processing, sterilization and treatment of organic waste, has been a hot research topic. However, due to the complexity that originates from the coexistence of abundant reactive species, its mechanism is still difficult to understand. Until now, reactive plasma diagnosis has been one of the most challenging tasks. Therefore, further study on nanosecond pulse discharge plasma is needed to investigate its mechanism. In this thesis, we investigate the time evolution of the electron energy probability function, which is represented by a bi-Maxwellian distribution. According to the effective electron temperature calculation, we find that there are more high-energy electrons that play an important role in the excitation and ionization processes than low-energy electrons. Furthermore, variations of the effective electron temperature are presented versus other discharge parameters, such as pulse width time, pulse rise time and gas pressure.Recent activity in upper-atmospheric, space, and plasma physics has further stimulated the research in electron-molecule collision. Because of the abundance of nitrogen in the earth’s atmosphere, electron-collision cross sections for nitrogen are of particular interest in explaining such natural occurrences as the aurora, the air-glow, and lightning. Simulation results of electron-collision excitation cross sections of the N2first positive bands are presented here. We find that the first positive bands exhibit sharp peak at about10eV. and the excitation cross sections are highest for the lowest vibrational quanta and decrease with the higher vibrational quanta. Clearly, for different electron energies, the lowest vibrational levels of A state are populated most efficiently. Moreover, we investigate electron-collision excitation cross sections of the N2first positive bands at the electron energy of the maximum of the sharp peak, which are found to be in agreement with other measurements. This is vitally important for theoretical simulations and further experimental measurements.