The Afterglow of Noble Gas Plasmas: Recombination and Excited States Formation

在这个项目中，惰性气体等离子体的余辉提出了广泛的研究，重点是三体复合（TBR）过程导致的激发态的形成。目的是尽可能完整地了解余辉中的TBR过程以及激发态动力学。为此目的，将调查过程的不同方面。测量电子温度和等离子体密度以及由复合产生的激发态是要进行的调查之一。结果将进行比较，数值模拟和分析估计，导致一个完整的自我一致的描述过程中的余辉。本项目采用微波干涉仪测量等离子体密度。为了测量低电子温度（在气体温度范围内），将使用减速场能量分析仪。在复合过程中产生的高激发态将通过吸收光谱测量。后备计划是使用腔衰荡光谱法。将发展一个低压氩余辉的碰撞辐射模型，并用于分析某些氩谱线的强度。这将提供一个独立的测量电子密度和可能的温度，以及激发态。对所记录的光谱的分析（使用项目中使用的高速照相机）也将作为复合过程某些方面的实验证据。对于实验研究，可使用大型等离子体室。该室已投入使用，实验室内可提供部分诊断技术。这样就可以立即开始项目工作。将研究脉冲低压惰性气体等离子体。实验室的大体积允许在低压下维持高密度等离子体，并允许进入TBR的高密度区域，其中等离子体微场预计将发挥作用。迄今为止，尚未对该机制进行实验研究。这些调查的预期重要性是更好地澄清激发态的余辉及其潜在的工业应用（例如“智能脉冲”的基础上的里德伯态最大值或亚稳态最大值）的作用，并提供实验证据的碰撞辐射复合的一些基本方面。

In this project an extensive study of the afterglow of noble gas plasmas is proposed with a focus on the three-body recombination (TBR) process leading to the formation of the excited states. The aim is to get as complete as possible picture of the TBR process in the afterglow together with the excited states dynamics. For this purpose different aspects of the processes will be investigated. Measurements of the electron temperature and of the plasma density as well as of the excited states produced by the recombination are among the investigations to be performed. The results will be compared with numerical simulations and analytical estimations, leading to a complete self-consistent description of the processes in the afterglow. A microwave interferometer is applied for within the project for the measurements of the plasma density. For the measurement of low electron temperatures (in the range of the gas temperature) a retarding field energy analyzer will be used. The highly excited states, produced in the recombination process, will be measured by absorption spectroscopy. A fall-back plan would be to use a cavity ring-down spectroscopy. A collisional-radiative model for the low-pressure argon afterglow will be developed and used to analyze the intensity of certain argon lines. This will provide an independent measure of the electron density and possibly temperature, as well as of the excited states. The analysis of the recorded spectra (using a high-speed camera applied for in the project) will also serve as experimental evidence for certain aspects of the recombination process. For the experimental investigations a large plasma chamber is available. The chamber is operational and part of the diagnostic techniques to be used are available in the laboratory. This permits the immediate start of the work on the project. Pulsed low-pressure noble gas plasmas will be investigated. The large volume of the experimental chamber allows sustaining high density plasmas at low pressures and gives access to a high-density regime of the TBR where the plasma microfields are expected to play a role. This regime has not been investigated experimentally up to now. Expected importance of these investigations is to better clarify the role of the excited states for the afterglow and its potential industrial applications (e.g. “smart pulsing” based either on the Rydberg states maximum or metastable states maximum) and to provide experimental evidence for some fundamental aspects of the collisional-radiative recombination.