Research On The Key Processing Factors That Influence The Machining Of The Fused Silica With Reactive Atmospheric Pressure Plasma

Inertial Confinement Fusion technology, micro-electronic technique and all kinds of high level weapon systems in aerospace field all demand the optical matetial(Fused Silica) with the ultra-smooth surface. Nowadays there are many kinds of ultra-precision machining technologies dealing with Fused Silica. such as bowl feed polishing, float polishing, magnetorheological finishing, ion beam polishing, elastic emission machining,plasma assisted chemical etching, et al. Atmospheric pressure plasma processing is a new developing ultra-precision machining technology, compared with other ultra-precision machining technologies, it is a method using chemical reaction between active radicals excited by plasma and workpiece surface atoms, which can't damage the optical surface; it has many advantages, such as higher processing efficiency, non-affected layer, non-second damage and lower cost. This technology has been used in optical components manufacture overseas, however in China, research in this area is still in its infancy, there are many problems need to be addressed urgently. This dissertation focuses on the processing of fused silica with atmosphericplasma processing, aiming at finding the discipline of various factors on the processing efficiency and surface quality with the theoretical and experimental analysis.Firstly, the dissertation introduces the theory of atmospheric plasma processing, and then designs a new atmospheric plasma generating device (plasma torch), which is used in optical components manufacture, and then studies it's characteristics when the plasma torch works in the plasma jet and plasma contact two processing modes. Then, in this dissertation, with the processing efficiency (material removal rate) as the research object, based on the two plasma processing modes, from the view of the plasma spectral intensity and the processing temperature, using the spectral quantitative analysis theory and infrared temperature measurement theory, we get the discipline of plasma reactive gas content on the material removal rate: With the increasing concentration of reactive gas CF4, the material removal rate of the atmospheric pressure plasma jet firstly rises, and then drops; the addition of O2 can improve the material removal rate. Then study the discipline of input power, process distance and process time on the material removal rate respectively, and we note that With the increasing input power, the reducing processing distance, the material removal rate rises, and the material removal rate is more or less constant for the process time.At last,with the final surface quality as the research object, we verify the conclusion which is got by quantum chemistry that the necessity of lower material removal rate for reducing the surface roughness in a way though experiment. Then using the nanoindentation technology we verify another conclusion: The atmospheric pressure plasma can remove the affected layer in the workpiece surface, and do not introduce the second damage.The content of this dissertation show that the atmospheric plasma processing can improve the mechanical properties of optical components, which has an important significance for improving the overall performance of the optical system.