Direct Injection Multi-Gas Inductively Coupled Plasma Source for Industrial Applications

Abstract

Summary form only given. A new direct injection multi-gas inductively coupled plasma (ICP) source is developed. With the new ICP source, not only Ar but He, O2, N2, CO2, air and their mixture gas plasma can be stably generated in the atmospheric pressure. Furthermore, aqueous solutions can be introduced directly into the plasmas using common pneumatic nebulizer. To generate molecular gas plasma and to realize direct injection, higher RF power is necessary because dissociation of molecules (plasma gases or aqueous solutions) needs large power. Therefore, the torch has external gas-cooling system. The torch consists of coaxial three quartz glass tube and the carrier gas, the plasma gas and the cooling gas flow between the tubes. When appropriate cooling gas species and flow rate were chosen, immixing of cooling gas and atmospheric air into the plasma can be reduced. Furthermore, to generate adequate vortex flow of plasma gas at the plasma generating region the torch has two different i.d. plasma gas inlets. Smaller inlet is used for helium gas that has about 9 times higher kinematic viscosity than other gases. Larger inlet is used for other gases or in the case of higher helium gas flow rate. With this new plasma source, atmospheric plasmas of various components (gas and impurities) with arbitrary ratio can be generated freely. So it is suitable for synthesis of diamond or carbon nano-tube, atmospheric plasma processing, CVD, treatment of surface, decomposition of industrial waste and so on