水素放電による負イオン生成に関する数値計算 (II)

H^-生成のプラズマパラメータ依存性

抄録

Dependence of H^- production on plasma parameters (i. e. electron density n_e, electron temperature T_e and hydrogen gas pressure p) is studied by using a set of particle balance equations in a steady state hydrogen plasma. The model includes six species of vibrationally excited hydrogen molecules H₂* (vibrational level v″=5-10) which are important for H^- production. Particular attention has also been paid to wall effects on H^- production. So, both the wall recombination coefficient γ₁ for H and the wall de-excitation collision parameter γ₂ for H₂* (v″) are treated as numerical parameters.
With increasing T_e, H^- yield decreases. Both n_e and p have some optimum values for H^- production. The most significant point is that ion species ratios depend strongly not only on plasma parameters but also on wall parameters, i. e. γ₁ and γ₂. For H^- production, the optimum condition is that γ₁≅1 and γ₂<<1.