微波干涉仪测量羽流电子密度反演方法

利用微波干涉仪进行推进器羽流密度测量的反演方法研究.重点针对羽流等离子体密度反演的Abel逆变换数值求解,采用离散化算法、三次样条插值算法、Hankel-Fourier算法以及Nestor-Olsen算法等四种方法进行仿真分析和比较.通过对这四种方法在无噪声和有噪声两种情况下反演误差的比较,找出适用于实际干涉仪数据处理的方法;通过对采样点数和反演之间的关系分析,给出解决欠采样问题的方法和数值参考;在分析比较的基础上,总结数值处理的必要步骤.利用模拟实验测试数据进行验证并对反演结果进行分析. 

Retrieval of Plume Density Profile by Microwave Interferometry

Microwave interferometer is an efficient tool for non-intrusively diagnosis of electron density of plasma,which can be used for the measurement of plume of helicon plasma thruster. Four different numerical Abel inversion algorithms,including the discretization method,the cubic spline interpolation method,the Hankel-Fourier transform method and the Nestor-Olsen method, are used to retrieved the plume density profile that is detected by microwave interferometry for the cases with and without noise.After analysis of the effect of sampling density on the retrieval error,the smoothing and interpolating solution is proposed to mitigate the under-sampling related problem.As a summary,the procedures of the retrieval and processing are proposed.Two principle verification experiments with microwave network analyzer have been done.In the first experiment,a circular pipe is measured as a axial symmetrical target,which simulates the plume,and the retrieval results match well with the shape of the pipe.In the second experiment,spatial resolved integrated phase shifts are retrieved by Abel algorithm.The radial electron density profile within the plume is calculated.The experiments and their results verify the performance and validity of both the system design and the retrieval algorithm.