OPTIMIZATION METHOD FOR ELECTRON ENERGY DISTRIBUTION FUNCTION IN NON-EQUILIBRIUM PLASMA

Abstract

Electron energy distribution function (EEDF) in non-equilibrium plasmas often differs from Maxwellian distribution. Therefore, it is essential to determine the EEDF experimentally for accurately deducing the plasma parameters and rates of plasma-chemical processes. Langmuir Probe is a robust diagnostic tool allowing the estimation of EEDF by the differentiation of I-V curve. However, possible distortions in differentiation process should be handled cautiously. This paper focuses on Maxwellian optimization method for the determination of EEDF from Langmuir probe I-V curve where EEDF is modeled as perturbations around Maxwellian distribution. The proposed optimization method is implemented on the Argon glow discharge plasma experimental data. The results obtained by the proposed Maxwellian optimization are compared with the ones obtained by commonly used Savitzky-Golay filtering method and the polynomial optimization method. The comparison indicates that it is vital to choose the appropriate model function to begin with for the optimization procedure to be satisfactory.