A new smoothing method for obtaining the electron energy distribution function in plasmas by the numerical differentiation of the I‐V probe characteristic

A new smoothing method has been used to obtain the electron energy distribution function (EEDF) in plasmas by evaluating the second derivative of the I‐V characteristic of a probe inmersed in the plasma. The smoothing method is based on the use of the instrument function. A comparison with other smoothing techniques has permitted us to show the advantages in using the new smoothing method. The experimental setup used to measure the I‐V probe characteristic fast and accurately is also presented. The smoothing method was tested by measuring the EEDF in an argon dc discharge at different conditions of the gas pressure and discharge current. The plasma parameters (electron density and temperature) evaluated from the EEDF were compared with those evaluated by using other classic diagnostic methods obtaining a quite good consistency among them.