Allan J. Lichtenberg and V. Vahedi and Michael A. Lieberman and T. Rognlien

EECS Department, University of California, Berkeley

Technical Report No. UCB/ERL M93/74

, 1993

http://www2.eecs.berkeley.edu/Pubs/TechRpts/1993/ERL-93-74.pdf

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 r.f. driven oxygen plasma for two cases: (1) p=50 mTorr, neo = 2.4x10 (15) m-3, and (2) 10 mTorr, new = 1.0x10 (16) m-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 is almost equal to 8, while in the higher power case alpha sub 0 is almost equal to 1.3. Using an electorn energy distribution that approximates the simulation distribution by a two-temperature Maxwellian, the analytic values of alpha sub zero are found to be close to, but somewhat larger, than the simulation values. The average electron temperature found self-consistently 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.

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BibTeX citation:

@techreport{Lichtenberg:M93/74,
    Author= {Lichtenberg, Allan J. and Vahedi, V. and Lieberman, Michael A. and Rognlien, T.},
    Title= {Modeling Electronegative Plasma Discharges},
    Year= {1993},
    Month= {Jul},
    Url= {http://www2.eecs.berkeley.edu/Pubs/TechRpts/1993/2437.html},
    Number= {UCB/ERL M93/74},
    Abstract= {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 r.f. driven oxygen plasma for two cases: (1) p=50 mTorr, neo = 2.4x10 (15) m-3, and (2) 10 mTorr, new = 1.0x10 (16) m-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 is almost equal to 8, while in the higher power case alpha sub 0 is almost equal to 1.3. Using an electorn energy distribution that approximates the simulation distribution by a two-temperature Maxwellian, the analytic values of alpha sub zero are found to be close to, but somewhat larger, than the simulation values. The average electron temperature found self-consistently 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.},
}

EndNote citation:

%0 Report
%A Lichtenberg, Allan J. 
%A Vahedi, V. 
%A Lieberman, Michael A. 
%A Rognlien, T. 
%T Modeling Electronegative Plasma Discharges
%I EECS Department, University of California, Berkeley
%D 1993
%@ UCB/ERL M93/74
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/1993/2437.html
%F Lichtenberg:M93/74