development of a space-borm LEF-TOF Type Ion Energy Mass Spectrometer

本文介绍了一台LEF-TOF型高质量分辨率离子能质谱仪的设计、制作和定标实验。在第一年，我们计算了入射离子的轨道和传感器内部产生的二次电子。根据数值计算的结果，对电极的形状和结构进行了优化。在此计算结果的基础上，我们制作了位置传感顶端MCP阳极。虽然MCP阳极的测量性能与预期的基本一致，但我们发现了一些需要改进的地方。我们还制作了碳箔的支架，这是质谱仪的一部分，并测量了碳箔允许的最大压差。我们发现，在3331pi网目上，1.2μg/cm~2碳箔可以在高达5.0×10~(-2)atm的压差下使用。第二年，我们制作了离子质谱仪，并通过注入氦、碳、氮、氧、钠和钾离子进行了刻度实验。我们发现，光离子(氦、氮等)的探测效率。高于重离子(钠、钾等)。因为轻离子更容易通过碳箔，而且碳箔的角散射较小。通过改变碳箔的厚度，我们发现应该使用最薄的碳箔(0.5μg/cm2)，才能实现足够高的重离子探测效率。在第三年，我们改进了制作的离子质谱计和MCP阳极的性能。我们还对已有的能量分析器进行了改进，以便将制作的离子质量分析器与能量分析器组合在一起，构成离子能量质谱仪。

This research deals with the design, fabrication, and calibration experiment of an LEF-TOF type high mass resolution ion energy mass spectrometer. In the first year, we calculated the orbit of the incident ions and the secondary electrons that would be generated inside the sensor. The shape and the configuration of the electrodes were optimized according to the results of the numerical calculation. We fabricated the position sensing TOP MCP anode, on the basis of the results of this calculation. Though the measured performance of the MCP anode was almost as expected, we found some points that had to be improved. We also fabricated the holder of the carbon foil that was a part of the mass spectrometer and measured the maximum pressure difference permitted across the carbon foil. We found that the 1.2μg/cm^2 carbon foil on 3331pi mesh could be used under the pressure difference up to 5.0X10^2atm. In the second year, we fabricated the ion mass spectrometer and made a calibration experiment by injecting Helium, Carbon, Nitrogen, Oxygen, Sodium, and Potassium ions. We found that the detection efficiency of the light ions (Helium, Nitrogen, etc.) were higher than the heavy ions (Sodium, Potassium etc.) because the light ions were easier to pass through the carbon foil, and the angular scattering by the carbon foil was smaller. By changing the thickness of the carbon foil, we found that we should use the thinnest carbon foil available (0.5μg/cm^2) in order to realize the high enough detection efficiency for heavy ions. In the third year, we improved the performance of the fabricated ion mass spectrometer and the MCP anode. We also improved the energy analyzer that had already been developed so that we could put the fabricated ion mass analyzer together with the energy analyzer to construct an ion energy mass spectrometer.