Ion Source Plasma Parameters Measurement using Langmuir Probe

In this work, we present the experimental results of plasma parameters using a Freeman type ion source, such as electron number density ne, plasma electron temperature Te, floating potential Vf, and plasma potential VS. The measurements of these basic parameters of pure Ar plasma were done with a cylindrical Langmuir probe situated perpendicular to a relatively weak magnetic field, B = 20 mT and were performed under constant low Ar pressure 4.6 × 10-3 mbar. Different methods were implemented to calculate the electron and ion densities. We have concluded that some of these methods are subjected to significant inaccuracy, mainly due to the uncertainty of the plasma potential location. However, it has been recognized that the plasma ion density ni = 1.46 × 1014 m-3 found in this experiment using the ion current saturation part is the most reliable among the other values found, using the standard procedures from the electron retardation region (classic Langmuir method) and the electron saturation region of the measured probe I-V characteristic. The results of calculations confirm the validity of the Langmuir’s orbital-motion-limited theory for low pressure plasma and low value of the magnetic field