Elimination of the ion current effect while measuring the energy electron distribution function in a plasma using the probe method

An experimental method of ion current and its derivatives compensation, while measuring the energy electron distribution function and their temperature using the probe method, is proposed and implemented. The method is based on signal difference detection from two cylindrical probes of different diameters, when hydrodynamic approximation is true for describing the ion drift on the probe. The method effectiveness is experimentally proved. It is shown that the ion current theory at elevated pressures satisfactorily describes both the current dependence on probe potential and its second derivative.