Numerical Study Of Low Temperature Gas Discharge Phenomenon

Gas discharge with a long research history has attracted more and more attention in recent years for its rich non-linear phenomenon. This dissertation presents numerical simulation on multi-layer hydrodynamics, focusing on the four aspects as the followings:1. Different kinds of plasma sheaths in gas discharge. In numerical investigations, we find that the sensitivity to the surface electric-field intensity causes the high stiff ratio in cathode sheath equations, while the stiff ratio in cylinder coordinate is far lower than that in the plane shape. Consisting of both thermal electrons and beam electrons, the hot cathode beam-injected sheath is governed by the new form of Bohm criterion, which necessitates the critical speed of ion entering from the plasma area being not only faster than acoustic speed, but accelerating with the increase of the proportion of beam electron. The minimum critical value of ion flux density in Langmuir criterion diminishes compared with its typical form. It relates to both the electron flux density and the sheath shape as well as the surface electric-field intensity. Numerical mode in this dissertation also describes the correlation of the surface electric-field intensity in cathode sheath and the double-sheath with the bias voltage and ion density at the boundary of the sheath respectively. The investigation proves that the threshold of ion flux density required is lower than that in the cathode sheath. Concerning the discussion of anode sheath, we pointed out that it is the dissipation of the electron and ion that choose the electropositive or electronegative property, which differs according to various discharge device and modes.2. Four popular modes in gas discharge. The dissertation presents the hydrodynamics modes in gas discharge and analyzes the production and the loss of the charged particles in each of the four popular modes in the context of the specific equipments. It further points out that this basic competing mechanism is crucial for the stability of gas discharge. In numerical investigation, we distinguish the key factors influencing...