Ion and neutral temperatures in a novel ultrahigh-frequency discharge plasma

Ion and neutral temperatures are measured in an ultrahigh-frequency discharge plasma through Ar and Ne by Doppler-shifted laser-induced fluorescence. The ion and neutral temperatures are estimated to be ≈ 0.066 eV (770 K) for Ar⁺ and 0.033 ± 0.004 eV (380 ± 50 K) for Ne, respectively. These temperatures are lower than those reported for electron cyclotron resonance and helicon wave plasmas. The low temperatures are attributed to the low electron temperature (≈ 2 eV) and excellent uniformity of the UHF plasma.