Investigating the properties of argon-helium plasma mixture generated in the RF remote discharge system.

This article experimentally investigates the properties of argon-helium (Ar-He) glow-discharge plasma mixtures generated in a radio frequency (RF) hollow cathode discharge system, focusing on how plasma parameters vary with pressure, applied RF power, and helium fraction. Using Langmuir probe diagnostics and optical emission spectroscopy (OES), the study analyzes electron energy probability functions (EEPFs), electron density (nₑ), effective electron temperature (T_eff), plasma potential, and spectral line intensities of argon and helium. Key findings include a Druyvesteyn-like EEPF shape with depletion of high-energy electrons beyond 50% helium fraction, a maximum electron density at 50% helium, and increases in electron density, effective temperature, and emission intensities with rising pressure and RF power. The results also highlight that changes in helium fraction affect plasma composition and ionization dynamics, influencing plasma potential and ion flux relevant to plasma processing applications.