Characterization of Plasma Produced at 2.45-GHz Frequency in CW Mode by Electron Cyclotron Resonance Method Using Langmuir Probe and Optical Emission Spectroscopy

This article presents a detailed study of the plasma parameters in an electron cyclotron resonance (ECR) plasma source utilizing a double Langmuir probe and optical emission spectroscopy (OES). The studies are performed for a range of operating conditions, including microwave power (150–550 W) and gas pressures ( $10^{-3}$ – $10^{-4}$ mbar) in argon discharge. The generated plasma is confined by using a tunable magnetic field, produced by a set of three electromagnets in a flat and mirror configuration. The experimental results indicate that the flat magnetic field configuration produces higher plasma density and lower electron temperature when compared with the mirror magnetic field configuration. At a constant gas pressure, the ionization rate does not increase significantly with increasing microwave power. Conversely, at constant input microwave power, increasing gas pressure results in a marked increase in the rate of ionization. We also observed that at a given operating condition, the plasma density measured by using the Langmuir probe is lower while the electron temperature is higher as compared with the results obtained from OES data.