Mason Rod S, Miller Pat D, Mortimer Ifor, Mitchell David J, Dash Neil A
Department of Chemistry, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, United Kingdom.
Phys Rev E Stat Nonlin Soft Matter Phys. 2003 Jul;68(1 Pt 2):016408. doi: 10.1103/PhysRevE.68.016408. Epub 2003 Jul 23.
Ions created from the fast-flowing positive column plasma of a glow discharge were monitored using a high voltage magnetic sector mass spectrometer. Since the field gradient and sheath potentials created by the plasma inside the source opposed cation transfer, it is inferred that the ions detected were the field-ionized Rydberg species. This is supported by the mass spectral changes which occurred when a negative bias was applied to the sampling aperture and by the contrasting behavior when attached to a quadrupole analyzer. Reaction with H2 (titrated into the flowing plasma) quenched not only the ionization of discharge gas Rydberg atoms but also the passage of electric current through the plasma, without significant changes to the field and sheath potentials. Few "free" ions were present and the lifetimes of the Rydberg atoms detected were much longer than seen in lower pressure experiments, indicating additional stabilization in the plasma environment. The observations support the model of the flowing plasma, given previously [R. S. Mason, P. D. Miller, and I. P. Mortimer, Phys. Rev. E 55, 7462 (1997)] as mainly a neutral Rydberg atom gas, rather than a conventional ion-electron plasma.
使用高压磁扇形质谱仪监测辉光放电快速流动正柱等离子体产生的离子。由于源内部等离子体产生的场梯度和鞘层电位阻碍阳离子转移，因此推断检测到的离子是场电离的里德堡物种。这得到了向采样孔径施加负偏压时发生的质谱变化以及连接到四极分析仪时的对比行为的支持。与H2（滴定到流动的等离子体中）反应不仅淬灭了放电气体里德堡原子的电离，还淬灭了通过等离子体的电流，而场和鞘层电位没有明显变化。几乎没有“自由”离子存在，并且检测到的里德堡原子的寿命比在低压实验中观察到的长得多，这表明在等离子体环境中有额外的稳定性。这些观察结果支持了先前给出的流动等离子体模型[R. S. Mason, P. D. Miller, and I. P. Mortimer, Phys. Rev. E 55, 7462 (1997)]，即主要是中性里德堡原子气体，而不是传统的离子 - 电子等离子体。
