Glass Cleaning Based On Numerical Simulation Of Two-Dimensional Model And Experiment Of Glow Discharge

Vacuum glass has lots of advantages. However, due to gas adsorption and desorption on its surface, it has not yet been large applied into daily life. The traditional heating method cannot meet the cleaning requirements of large area glass. To solve this problem, plasma bombardment cleaning in a vacuum environment is proposed to get clean glass surface, which also can improve the glass quality and lifetime. Thus this method has very good research and application prospect.Currently, plasma cleaning is confined to the microelectronics, flat-panel computer monitors, and other industries. Cleaning for large area glass acting as building materials is almost blank. Using COMSOL Multiphysics software and starting from the design of discharge structure in glass cleaning equipment, mathematical and geometric model are built. Based on relatively simple structure of discharge cleaning, the discharge electrode, working voltage, working pressure and other process parameters are simulated and analyzed to study the effects of plasma characteristics on the desorption of the glass surface. Plasma density, electron temperature distribution, and ion current density curves are obtained through the simulation. The results show that the effects of negatively charged electrode is better than that of the positively one. The reason may be that when the electrode is negatively charged, the glass potential can be useful, and electrons and positive ions both can continuously clean the glass. With the increase of discharge voltage, the energy of charged particles increase, but due to high electric field, the ion current density can be uneven with the enhanced attraction of electrode. After comprehensive consideration, the optimal working voltage is -1000 V. Similarly, with the increase of operating pressure, plasma ionization rate increases, but the energy of charged particles decrease due to collisions, the optimal work pressure is 8 Pa.In this article, structural parameters of glass cleaning are also simulated and analyzed, including the cross shape of electrode, the distance h between the electrode and the glass, studio width H, distance L between electrodes, electrode arrangement, etc. The optimization of structure parameter of the cleaning equipment is based on the orthogonal experiment. The best simulated parameters according to the orthogonal table as the following:h=12.5 mm, H=35 mm, L=25 mm. The reason may be that the studio width is smaller than the rest of the group; the ionized Ar ions in the four corners are near from the outside electrode. The gravitational pull distance of the outer electrode is short, and the Ar ions can escape from the outside electrode and reach the middle area of the glass, so the glass cleaning effects will be better. This set of parameters is of great significance for the design of cleaning equipment and production line of vacuum glass. The results show that the cleaning effect of the section shape electrode is better than that of the circular cross section electrode. The cleaning effect of electrode pairs arrange is better than that of the single electrode arrangement. These results are helpful for the improvement of the cleaning equipment.Additionally, some experiments are carried out to verify the numerical simulation results. Experimental results show that when the cleaning work voltage is of-1000 V, the glass surface is very clean and smooth. As the working voltage increases to-1500 V, though the surface is still clean, it is uneven due to the sputtering pit, which is not good for the subsequent coating procedure. The validity of the simulation result is verified. The results can be used to guide the improvement of glass cleaning equipment and the optimization of process parameters.The results in this paper provide some practical guidance and reference value for the process parameter optimization of glass cleaning equipment, the structural design, and improvement of existing equipments.