[P-CG20] 宇宙・惑星探査の将来計画および関連する機器開発の展望

[PCG20-15] Development of an ion energy-mass spectrometer for observations of suprathermal ions originating from the ionosphere using computer simulation

寺澤 賢哉¹、浅村 和史²、永谷 朱佳理¹、竹内 亘平¹、*三好 由純¹ (1.名古屋大学宇宙地球環境研究所、2.宇宙航空研究開発機構)

キーワード：粒子計測器、超熱的イオン、電離圏、磁気圏

Heavy ions such as oxygen ions, nitrogen ions, and molecular ions, flow out from the Erath’s ionosphere along the geomagnetic field lines. These ions are originally thermal ions from the ionosphere. They are believed to be heated and transported to the magnetosphere by magnetic mirror force. However, the heating mechanisms from thermal to suprathermal energy range are still unclear. To clarify the mechanisms, we are developing a suprathermal ion energy-mass spectrometer for the next sounding rocket experiment “LAMP-2” and the future geospace satellite mission “FACTORS”. One of the scientific objectives is to observe the 3D distribution function for each ion species. To achieve this, several functions are required, including a sensitivity adjustment function to prevent detector saturation caused by high count rate from thermal ions in dense plasmas. The designed instrument consists of mainly two components: an electrostatic energy-per-charge analyzer and a mass analyzer using a Time-Of-Flight (TOF) method with a linear-electric field (LEF) system. Using a dedicated electrode system, we achieve sufficient mass resolution to discriminate N+ and O+. Furthermore, the field-of-view (FOV) of the instrument can be expanded by sequentially controlling the looking direction, and the sensitivity is also adjustable. In this presentation, we report on the design of the instrument and outline our future development plans.