基于超精细结构碰撞辐射模型的霍尔推力器光谱诊断研究

The electric propulsion system, including the Hall effect thruster, is an important application of plasma physics in the area of space technology. It is utilized to control various spacecrafts and is the main thruster for deep-space exploration. Many novel types of electric propulsion systems are developed recently, including the magnetic-focusing, magnetic-shielding, high-power, and small-size thrusters; in these cases, it is difficult to apply the previous optical method based on the assumption of optically-thin plasma as well as the Langmuir probe for diagnostics of plasmas in the optically-thick region of discharge channel under strong electromagnetic field. This is a critical limitation to the current fundamental research of novel plasma thrusters. In this project, a kind of optical emission spectroscopy method based on the most recently developed hyperfine-structure collisional-radiative model is proposed. Optical diagnostics of discharge channel, plume, and cathode region can be accomplished. A complete set of plasma parameters can be measured, the spatial evolution of them along the axial, radial, and tangential directions can be investigated, and the sources of uncertainties can be analyzed. The physical model and diagnostic technique obtained in this project are not only important for the research of Hall effect thrusters and ion thrusters but also helpful for the other plasmas under similar conditions, including fusion edge region, electron cyclotron resonance, helicon discharge, and space plasma.

以霍尔推力器为代表的电推进装置是等离子体物理学在航天科技领域的重要应用，为航天器提供姿态控制和轨道修正，并作为深空探测的主推力器。随着磁聚焦、磁屏蔽、大功率、微尺度等新一代高性能推力器的涌现，传统上基于光学薄假设的光谱方法以及探针技术已经难以准确诊断推力器放电通道内处于强电磁场环境和光学厚状态的关键区域，极大地制约了新型推力器的物理研究。本项目立足于最新的超精细能级结构Kr-Xe碰撞辐射模型，建立放电通道内光学厚区域的全新光谱诊断方法，以实现推力器放电通道、羽流区和阴极区域的全面诊断。并进一步完成对各等离子体参数沿轴向、径向和周向的空间演化研究和诊断结果的不确定度分析。本项目建立的物理模型和诊断方法不仅能大幅推动霍尔推力器、离子推力器等装置的基础研究，还同样适用于相近物理条件下的等离子体，如聚变边界、电子回旋共振、螺旋波放电和空间等离子体等。

针对我国航天等离子体推进领域对先进诊断方法的迫切需求，本项目以霍尔推进器的光谱诊断为主要目标，对超精细能级结构碰撞辐射模型和光谱神经网络分析方法开展了深入研究。针对国内外原有工作缺乏离子碰撞辐射过程定量描述和准确可靠反应参数的问题，本项目基于全相对论量子力学方法建立了一套完整的氙离子碰撞截面和爱因斯坦系数基础数据，并利用新型霍尔推进器进行了实验验证，被LXCat和NIST等国际权威平台所引用。利用新模型研究了霍尔和离子等主要推进器不同区域的激发态原子和离子动力学机制，在此基础上构建了推进器等离子体中电子温度、工质离子密度、侵蚀产物原子密度等关键参数的光谱诊断新方法。针对真空测试环境中噪声和干扰问题，以及理论模型假设和简化可能导致的不准确性问题，在国际上率先提出利用特殊复合神经网络模型来抑制光谱诊断噪声的方法，该方法融合了实测光谱特征、理论光谱特性和量测噪声特征，在联合航天专业计量测试单位开展的新旧方法对比考核中，新方法表现出抑制多种误差因素的能力，因此也通过成果转化应用于最新的航天推进器标准测试平台。本项目资助下已发表学术论文16篇，做国际会议特邀报告7次，授权国家发明专利4项，培养研究生6人。