Characterization of electron cyclotron resonance hydrogen plasmas

Electron cyclotron resonance (ECR) plasmas yield low energy and high ion density plasmas. The characteristics downstream of an ECR hydrogen plasma were investigated as a function of microwave power and magnetic field. A fast‐injection Langmuir probe and a carbon resistance probe were used to determine plasma potential (V_p ), electron density (N_e ), electron temperature (T_e ), ion energy (T_i), and ion fluence. Langmuir probe results showed that, at 17 cm downstream from the ECR chamber, the plasma characteristics are approximately constant across the center 7 cm of the plasma, for 50 W of absorbed power. These results gave V_p =30±5 eV, N_e =1×10⁸ cm⁻³, and T_e =10–13 eV. In good agreement with the Langmuir probe results, carbon resistance probes have shown that T_i≤50 eV. Also, based on hydrogen chemical sputtering of carbon, the hydrogen (ion and energetic neutrals) fluence rate was determined to be 1×10¹⁶ /cm² s at a pressure of 1×10⁻⁴ Torr and for 50 W of absorbed power.