Doppler shift measurements of ion energy distribution widths in an electron cyclotron resonance/multipole hybrid reactor

An optical emission spectroscopy diagnostic was used to measure the Doppler broadening of a Cl⁺ emission line in a plasma generated in an electron cyclotron resonance/multipole hybrid reactor. The broadening of the emission line was found to be correlated with Langmuir probe measurements of the electron temperature. It is postulated that the Doppler broadening is related to the electron temperature through the plasma potential. Deviations to the correlation occur at high microwave powers, suggesting the existence of another type of ion broadening.