Langmuir probe measurements in nanodust containing argon-acetylene plasmas

This paper presents the results regarding the influence of cyclic growth of nanoparticles from the gas phase on the parameters of a low-temperature plasma. The measurements were carried out in an asymmetric RF (13.56 MHz) discharge in mixtures of argon and acetylene gases. The main plasma parameters such as the electron temperature, electron density and plasma potential were determined by a Langmuir probe and compared with the discharge self-bias voltage signal. The contamination problem of the electric probe tip in a reactive plasma due to the sticking of nanoparticles and radicals was minimized by applying a rapid “complex” sweep pattern of the probe voltage. The method based on the oscillation of the probe voltage with a frequency higher than the frequency of dust particles. The measurement results show a decrease in the electron density during the cyclic growth due to their absorption on the surface of the nanoparticles. On the contrary, the electron temperature and plasma potential increase. Additionally, a laser light scattering system was used to evidence the presence of the dust particle cloud in the vicinity of the probe position.