3C-O1-1020 PDF
月・惑星圏プラズマ観測を目的とした質量/同位体分析器の開発
In situ low-energy ion measurement in terrestrial or planetary plasma environment has been done with a variety of ion analyzers onboard spacecraft. When measuring a variety of ions originating from planetary atmospheres, we need to be able to measure the ion composition with high mass resolution. Composition measurement of space plasmas is of great interest. Time-of-flight (TOF) analysis for space use had been applied mainly for observing highly energetic particles. The development of TOF techniques using thin carbon foil made it possible to measure lower-energy ions. Moreover, a TOF technique with a specific electric field, called a linear electric field (LEF), has been used for measuring space plasmas around the Moon and planets. We developed an LEF-TOF ion mass analyzer, MAP-PACE-IMA, for Kaguya which has measured ions originating from the lunar exosphere and surface. In addition, we are now preparing MPPE-MSA for the BepiColombo mission. For future isotope measurements around moons, planets and asteroids, we have also started developing a new-type mass analyzer. One of our scientific objects is to investigate the Martian atmospheric escape and evolution, in which the mass resolution of M/dM ＞3,000 is required for discriminating N2+ from CO+ in the Martian ionosphere. We have developed a test model, which employs a method of Multi-turn TOF mass spectrometry (MULTUM). We present our mass analyzers, observation results and science objective of the future mission.