Simulation of Ar /O2 Mixture

1. Leila Taghizadeh, Christophe Leys Leila.taghizadeh@ugent.be Jozef Plateaustraat 229000 Gent Plasma chemistry has found new applications in recent years, such as aerodynamics, nanotechnology, sterilization, etc. In many these applications the knowledge of kinetics and understanding of the production of radicals and excited species are important for optimization of plasma processes; there are not enough experimental data and due to huge number of radical and excited species, it is not easy to estimate these data. This work is to concentrate on simulation of DC discharge in Ar/O2 mixture which is widely used in technological process e.g. in deposition of oxide layers, plasma etching, plasma sterilization, etc. Introduction Objective Using a global zerodimensional model to study the dissociation process and the presence of negative ions and metastable species in a low pressure Ar/O2 mixture. The idea of using a global model is to concentrate on chemistry of the plasma produced in the discharge and neglecting the complexity arises when spatial variation is taken into account. Simulation of Ar/O2 Mixture Results Results The Model A 0D, ZDPlasKin, solves Boltzmann equation to calculate EEDF and electron temperature. The reaction rate and densities are calculated and process is repeated for the new plasma condition. 12 Oxygen species: O, O2 , O(1D), O2(a1), O2(b1) , O2(H), O3, O2+, O+, O-, O2- and O3- 5 Ar species: Ar, Ar(m), Ar(r ),Ar(4p) and Ar+ 169 reactions The electron temperature versus argon content for different applied power. How ZDPlasKin Works INITIAL CONDITION The fraction of O2+ versus the fractional argon content for different applied power. New Densities Boltzmann Equation References [1] J. T. Gudmundsson and E. G. Thorsteinsson, Oxygen discharge diluted with argon: dissociation processes, Plasma Source Sci. Technol. 16 (2007) 399-412 [2] A. Bogaerts, The afterglow mystery of pulsed glow discharge and the role of dissociative electron-ion recombination,, J. Anal. At. Spectrom., 22(2007) 502-512. [3] F. J. Gordillo-V´azquezl, Air plasma kinetics under the influence of sprites J. Phys. D: Appl. 41(2008)234016. [4] S. Pancheshnyi et al, Computer code ZDPlasKin University of Toulouse, LAPLACE, CVRS-UPSINP, Toulous, France, 2008 (a) The density of neutral oxygen species, (b) the density of neutral argon species (c) the density of charged particles versus the fractional argon content in a metal cylinder (R=10cm and L=10cm, p=10mtorr, Tgass=600K and P=500W) EEDF Reaction Rate Electron Temperature Conclusion A zero-dimensional model for Ar/O2 mixture is developed, Boltzmann equation is solved in order to include effect of non-Maxwellian electron energy distribution function in calculation. Results of simulation have shows that the deviation from Maxwellian distribution will decrease by increasing the applied power. Also, it is revealed that O2+ is the dominant positive ions but the [O2+ ]/[O+] decreases with increasing power. Electron temperature increases with increasing the fraction of argon up to 88% in the mixture due to higher ionization potential of argon compared to molecular and atomic oxygen. The result is comparable with published data from simulation in reference.