Nikolay Britun, Michael K. T. Mo, Shih-Nan Hsiao, Fatima J. T. Arellano, Makoto Sekine, Masaru Hori
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This study discusses Ar-based actinometry in low-pressure (roughly <1 kPa) plasma discharges with an emphasis on multiple line ratios. The work is particularly focused on the method’s applicability, the choice of Ar cross sections, and potential error sources. The influence of the additional excitation mechanisms is analyzed based on both experiments and modeling. The optical transitions for F, O, H, N, and P atoms along with expressions for their number density are presented, not requiring high optical resolution for measurements. 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The optical transitions for F, O, H, N, and P atoms along with expressions for their number density are presented, not requiring high optical resolution for measurements. 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引用次数: 0
摘要
等离子体产生的原子或分子的数量密度是基础研究和应用的重要参数。它可以用真空紫外吸收光谱法进行直接测量,但由于可能需要激光等笨重的设备,这种方法主要只能在实验室条件下使用。相比之下,光学锕系元素测量法是一种只利用等离子体自发辐射的替代方法。这种技术依赖于所谓的电晕激发,并使用未知浓度气体和已知浓度气体之间的发射线比率(在最后一种情况下称为放线仪)。由于使用了线比,如果已知激发截面,就不需要额外的密度校准。本研究讨论了低压(大约 1 kPa)等离子体放电中基于氩的放电测量法,重点是多线比。这项工作尤其关注该方法的适用性、氩截面的选择以及潜在的误差源。根据实验和建模分析了附加激发机制的影响。在不要求高光学分辨率测量的情况下,介绍了 F、O、H、N 和 P 原子的光学跃迁及其数量密度表达式。为了验证方法,研究表明在低压射频放电中,通过仔细选择光学跃迁,可以实现放电测量数据与校准测量数据之间近乎完美的一致性。
Optical actinometry for number density measurements in low-pressure plasmas: Advantages, error sources, and method validation
Number density of plasma-generated atoms or molecules is an important parameter for both fundamental research and applications. It can be measured in a straightforward manner, using vacuum-ultraviolet absorption spectroscopy, which is mainly possible in laboratory conditions as it may require bulky equipment, such as lasers. By contrast, optical actinometry is an alternative approach that only uses spontaneous emission from the plasma. This technique relies on the so-called corona excitation and uses emission line ratios between the gases with unknown and known concentrations (called actinometer in the last case). As a result of using line ratios, the additional density calibration is not required if the excitation cross sections are known. This study discusses Ar-based actinometry in low-pressure (roughly <1 kPa) plasma discharges with an emphasis on multiple line ratios. The work is particularly focused on the method’s applicability, the choice of Ar cross sections, and potential error sources. The influence of the additional excitation mechanisms is analyzed based on both experiments and modeling. The optical transitions for F, O, H, N, and P atoms along with expressions for their number density are presented, not requiring high optical resolution for measurements. For the sake of method validation, it is shown that in low-pressure radiofrequency discharges, a nearly excellent agreement between the actinometry data and the calibrated measurements can be achieved by careful selection of optical transitions.
期刊介绍:
The Journal of Applied Physics (JAP) is an influential international journal publishing significant new experimental and theoretical results of applied physics research.
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