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The etching mechanism of MgO thin films in Cl2∕Ar plasma was investigated. It was found that the increasing Ar in the mixing ratio of Cl2∕Ar plasma causes nonmonotonic MgO etch rate, which reaches a maximum value at 70%Ar+30%Cl2. Langmuir probe measurement showed the noticeable influence of Cl2∕Ar mixing ratio on electron temperature and electron density. The zero-dimensional plasma model indicated monotonic changes of both densities and fluxes of active species. At the same time, analyses of surface kinetics showed the possibility of nonmonotonic etch rate behavior due to the concurrence of physical and chemical pathways in ion-assisted chemical reaction.

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: Numerical analysis was done to evaluate the fluid distribution inside of the mixing quencher to increase the reaction efficiency of the aqueous hydrogen peroxide solution in the scrubbing column which is used for simultaneous desulfurization and denitrification. Effective injection of the aqueous hydrogen peroxide (H2O2) solution in the mixing quencher has major effects for improving the reaction efficiency in the scrubbing column by enhancing the mixing of the aqueous H2O2 solution with the exhaust gas. The current study is to optimize the array of nozzles and the spray angles of the aqueous H2O2 solution in the mixing quencher by using the computational method. Main concerns of the analysis are how to enhance the uniformity of the H2O2 concentration distribution in the internal flow. Numerical analysis was done to check the distribution of the internal flow in the mixing quencher in terms of RMS values of the H2O2 concentration at the end of quencher. The concentration distribution of H2O2 at the end of is evaluated with respect to the different array of the nozzle pipes and the nozzle tip angles, and we also analyzed the turbulence formation and fluid mixing in the zone. The effect of the spray angle was evaluated with respect to the mixing efficiency in different flow directions. The optimized mixing quencher had the nozzle array at location of 0.3 m from the inlet duct surface and the spray angle is 15° with the co-current flow. The RMS value of the H2O2 concentration at the end of the mixing quencher was 12.4%.