On the processing methods of the plane probe characteristics

Analysis of the plane probe characteristics implies besides analytical model the utilization of suitable numerical methods. Moreover, 'selecting' the plasma potential may have strong influence on the plasma parameters obtained from the experimental probe characteristics. In this paper a comparison is presented of three methods proposed and generally used, namely, test function method, semi logarithmic method and direct fit method of probe characteristic. Specifically, the analysis is made with respect to influence of the plasma potential on the plasma parameters obtained from probe characteristics under approximation of bi-Maxwellian distribution function for electrons. It was found that the values of the densities of two-electron populations are very sensitive with respect to plasma potential while the electron temperatures of two groups of electrons are not. In general selection of plasma potential is very disputable, since it may be somewhere between the values of probe potential proper to the maximum of first or second derivative of probe current. The experiments where made in a DP plasma system. (authors)