Analysis of Electron Energy Distribution Function from a Langmuir Probe Data Using the Bi-orthogonal Wavelet Transform

Abstract

Electron energy distribution function (EEDF) from the Langmuir probe (LP) data is important in the analysis of accurate plasma density and electron temperature. The determination of EEDF requires the 2nd derivative of LP data with respect to the probe voltage, which may enhance the noises in the probe data seriously. In order to filter the noise effectively, the wavelet transformation technique, especially the bi-orthogonal wavelet transform (BWT), was adapted to separate the noises from the 2nd derivative LP data. The accuracy of algorithm based on the BWT was evaluated with various noise levels for the Maxwellian distribution electrons. It provides the EEDF without losing the important information that has an advantage of minimizing the operator`s choices to precede the analysis of LP data