论文标题
阳性离子能对氘等离子体中负离子的碳表面产生的影响
Impact of positive ion energy on carbon-surface production of negative ions in deuterium plasmas
论文作者
论文摘要
这项工作的重点是在低压（2 pa）低功率（20 W）电容性仅在低压（2 pa）的低压（2 pa）中的阳性离子轰击的石墨表面上产生负面因子。将样品放置在质谱仪对面，并产生负偏见，以便可以从等离子体中自我提取表面产生的负离子，并通过质谱仪进行测量。质谱仪在样品表面上的负离子计数与正离子电流之间的比率定义了相对的负离子产率。分析了在10-60 eV范围内的负离子产量的变化与正离子能的变化。虽然在增加阳性离子撞击能量时，钻石表面的负离子产量正在降低，但石墨却大大增加。这一增加归因于20至40 eV之间的溅射机制的发作，这在质谱仪有效地收集了相当低的能量下产生负离子。钻石发生了相同的机制，但由于缺陷的产生和钻石电子特性丢失而导致电离概率的强烈降低来减轻。
This work focuses on the production of negative-ions on graphite and diamond surfaces bombarded by positive ions in a low pressure (2 Pa) low power (20 W) capacitively coupled deuterium plasma. A sample is placed opposite a mass spectrometer and negatively biased so that surface produced negative ions can be self-extracted from the plasma and measured by the mass spectrometer. The ratio between negative-ion counts at mass spectrometer and positive ion current at sample surface defines a relative negative-ion yield. Changes in negative-ion production yields versus positive ion energy in the range 10-60 eV are analysed. While the negative-ion production yield is decreasing for diamond surfaces when increasing the positive ion impact energy, it is strongly increasing for graphite. This increase is attributed to the onset of the sputtering mechanisms between 20 and 40 eV which creates negative ions at rather low energy that are efficiently collected by the mass spectrometer. The same mechanism occurs for diamond but is mitigated by a strong decrease of the ionization probability due to defect creation and loss of diamond electronic properties.
