Modelling of ferro-electric packed bed non-thermal plasma reactor for NF/sub 3/ treatments

Summary form only given. Ferro-electric packed bed non-thermal plasma reactor has been widely investigated for application to PFC removal etc. However, the plasma parameters of this non-thermal plasma reactor are not well understood in spite of fact that the fundamental characteristics of this reactor are relatively well known. In order to optimize operation of the ferro-electric packed bed reactor for gaseous PFC pollution controls, the physical model was developed to predict various plasma parameters based on experimental current-voltage characteristics. The chemical kinetic model to predict ion and radical species was developed for pure nitrogen plasma with and without trace PFC pollutant gases. Numerical modelling of ferro-electric packed bed nonthermal plasma reactor was conducted to remove trace NF/sub 3/ pollution gases from pure nitrogen. Simplified analytical physical model was obtained based on one-dimensional Poisson's equation for electric field and the ion transport equation with mobility term. The mean electron energy was obtained by swarm relationship with calculated electric field profiles and plasma neutral conditions. For chemical model of pure nitrogen, N/sup +/, N/sub 2//sup +/, N/sub 3//sup +/, N/sub 4//sup +/, N*, N/sub 2/* and electron were considered. Numerical results for trace NF/sub 3/ pollutant treatment will be presented and compared with experimental results. The bench-scale cylindrical shaped (plasma part: 30 mm i.d. and 20 min length) ferro-electric packed-bed plasma reactor consists of two metal mesh electrodes packed with spherical shaped of 3 mm diameter ferro-electric particles with dielectric constant 10000. The AC high voltage from a neon-sign transformer (15 kV, 30 mA, 60 Hz) was applied to the mesh electrodes. The results show that all the plasma parameters increase with increasing applied voltage, pellet dielectric constant and applied frequency. The results also show that the dominant ion is N/sub 4//sup +/ and the metastable molecule is much higher than that of radical and plasma densities for pure nitrogen gases. The results also show that NF/sub 3/ is much easier to removed by nitrogen plasmas compared with C/sub 2/F/sub 6/ and CF/sub 4/. PFC removal increases with increasing applied voltage and decreases with decreasing residence time, and agree well with experimental results.