The Application Of Plasma Needle And Mechanism Analysis By Spectrum

Compared to the vacuum plasma, the atmospheric DBD plasma has some merits because expensive vacuum system needs not to be built, and the operation is convenient. Therefore, the DBD plasma have wildly potential applications in industry. In this dissertation, a novel plasma needle was build with a funnel-shaped nozzle. Moreover, the discharging characteristics of the plasma needle and its several potential applications were studied.By special design, a DBD plasma plume was generated under an atmospheric pressure condition. The length of the plasma plume was about 2-4 cm, and its gas temperature was no higher than 316 K when the applied power was not higher than 28W. The preliminary characteristics of the plume and applications to the ablation of cultured human hepatocellular carcinoma (HCC) BEL-7402 cell line were presented. The effect of oxygen, which was injected into argon plasma afterglow region through a steel tube, was studied. The efficiency of argon-oxygen plasma depends sensitively on the oxygen concentration in argon plasma. Large differences between spectra in atmosphere and those in Dulbecco's modified eagle medium are found. It is found that ultraviolet rays, 0, OH, and Ar radicals can reach the bottom of solution and act on HCC cells and there is an optimum input power to get the most radicals. On the other hand, its applications in the inactivation of Streptococcus mutans (S.mutans), the most important microorganism causing dental caries, were presented in this paper. Oxygen was injected downstream in the plasma afterglow region through the powered steel tube. Its effect was studied via optical emission spectroscopy, both in air and in agar. Results show that addition of 26 mL/min O₂ does not affect the plume length significantly (ML/MIN denotes cubic centimeter per minute at STP).In addition, we treated the dye solution and landfill leach ate by using the downstream active gas of the plasma plume, and the results show the air downstream gas could degrade the color of the methyl violet 5BN, but did nothing to the aromatic derivates except oxygen gas. As a similar result, the oxygen downstream gas could also degrade the landfill leach ate effectively. The COD , conductivity and BOD, suspended matter was decreased by 50%,50%, 76% and 91% respectively, which meets the requirement of pre-treatment of the reverse osmosis.