Research On Atmospheric Pressure Plasma Generation Technique And Processing Technology

Atmospheric plasma is widely used to process fused silica for high removal rate and defect free.In order to overcome the problem of the last generation of arc-discharge plasma torch, an improvement scheme was put forward and a new torch was designed. A comparative experiment was carried out to prove the improvement scheme is reasonable. The different factor’s effect on removal rate was investigated by single factor experiment. Based on the result of single factor experiment, the orthogonal experiment was designed to acquire the primary-secondary order of each factor’s effect on removal rate.In the paper, the structure design and discharge properties of radio frequency (RF) powered capacitive coupled plasma(CCP) torch was studied.The experiment result shows:1) Two etching mode exist while arc discharge plasma contacts with fused silica. They are physical etching and reaction etching. When the work distance is short, the physical etching is more efficient than reaction etching. When the work distance is long, the reaction etching is more efficient than physical etching. The removal rate decreases by work distance at the beginning, and reaches the minimum at 3mm, then increases by work distance.2) Among the four factors, the work distance is most significant to removal rate, the pressure of carrier gas and the action gas flow rate followed. The removal rate is not a constant. The longer the work time takes, the lower the removal rate is.The removal rate gets maximum, when the work distance is 4mm, the N2 pressure is 0.010MPa, and the flow rate of SF6 is 1.5SLM, the removal rate is 16.8mm/min.3) The parallel plate type RF CCP torch and coaxial type RF CCP torch were designed in this paper. In both type of RF CCP torch, when the space between two electrodes is a constant, the lower the gas pressure is, the smaller the RF power of glow discharge is. The gas discharge got strongly when the RF power increased. But when the power exceeds a certain value, the area of discharge decreased rapidly, and the discharge condition changed, it is no longer glow discharge. Especially, in parallel plate type RF CCP torch, the space between two electrodes smaller, the power of glow discharge smaller.