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

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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.