Electrostatic waves in plasma: the case of an expanding microwave plasma sustained in argon

This work is devoted to the study of the electrostatic wave dispersion in plasma. Investigations are focused on waves with angular frequency ranging between the ion and the electron angular resonance frequency. The dispersion equation is resolved by means of a Fourier transform spectral method in the case of theoretical Maxwell-Boltzmann electron energy distribution functions (EEDFs), and in the case of experimental EEDFs measured by means of a Langmuir probe in microwave expanding plasma sustained in argon. The results show the change of the dispersion curve with the plasma parameters and the role of electrons and ions in the shape of the dispersion curve.