Modeling electronegative plasma discharges
- Department of Electrical Engineering and Computer Sciences and the Electronics Research Laboratory, University of California, Berkeley, California 94720 (United States)
- Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
A macroscopic analytic model for a three-component electronegative plasma has been developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is found. The electron density is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane rf driven oxygen plasma for two cases: (1) [ital p]=50 mTorr, [ital n][sub [ital e]0]=2.4[times]10[sup 15] m[sup [minus]3], and (2) 10 mTorr, [ital n][sub [ital e]0]=1.0[times]10[sup 16] m[sup [minus]3]. In the simulation, for the low power case (1), the ratio of negative ion to electron density was found to be [alpha][sub 0][approx]8, while in the higher power case [alpha][sub 0][approx]1.3. Using an electron energy distribution that approximates the simulation distribution by a two-temperature Maxwellian, the analytic values of [alpha][sub 0] are found to be close to, but somewhat larger than, the simulation values. The average electron temperature found self-cosistently in the model is close to that in the simulation. The results indicate the need for determining a two-temperature electron distribution self-consistently within the model.
- DOE Contract Number:
- FG03-87ER13727; W-7405-ENG-48
- OSTI ID:
- 5185868
- Journal Information:
- Journal of Applied Physics; (United States), Vol. 75:5; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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