Hiroyuki Toyota

令和3年度宇宙科学に関する室内実験シンポジウム（2022年2月28日-3月1日. オンライン開催) 2022 Symposium on Laboratory Experiment for Space Science (February 28-March 1, 2022. Online Meeting) 資料番号: SA6000178032 レポート番号: 32

第31回アストロダイナミクスシンポジウム (2021年7月26-27日. オンライン開催)著者人数: 14名資料番号: SA6000167077レポート番号: ASTRO-2021-C024 The 31th Workshop on JAXA Astrodynamics and Flight Mechanics 2021 (July 26-27, 2021. Online Meeting)

大気球シンポジウム 平成27年度（2015年11月5-6日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)）, 相模原市, 神奈川県 Balloon Symposium 2015 (November 5-6, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 資料番号: SA6000044007 レポート番号: isas15-sbs-007

The electrical performance of a glass-type space solar sheet (G-SSS) was demonstrated in space. G-SSS comprises InGaP/GaAs dual-junction and InGaP/GaAs/InGaAs triple-junction solar cells. It is lightweight solar generation sheet, less than 0.5mm thick. It is mounted on the "HISAKI" (SPRINT-A) small scientific satellite, which was launched on September 14, 2013. The initial flight data were successfully acquired and this flight demonstration was a world-first experiment for G-SSS using III-V multi-junction thin-film solar cells. The cells demonstrated superior performance and the electrical outputs matched the flight prediction.

Solar power sail that is being developed by JAXA as a planetary exploration spacecraft utilizes a combination of electric and photon propulsion system. The solar power sail requires a super lightweight flexible power generation system that uses thin film solar cells. We are developing a mounting method of the thin film solar cells on the membrane of the sail. Major issues of our study are shape control and connection between thin film solar array and thin film electrical wiring harnesses. We describe experimental results of shape control by oxide sputtering on the polyimide film and thin film solar cells and evaluation results of trial production of the thin film solar array connected with the thin film flexible wiring harnesses by heat sealing.

"Small space science Platform for Rapid INvestigation and Test", aka SPRINT - project is a new satellite series for scientific applications of Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS/JAXA). The design concept of the satellite bus is based on flexibility with alternative, and selectable options. SPRINT-A is the first satellite of the series, which aims to make scientific observations of planetary atmosphere at extreme-ultraviolet wavelength.

Supercapacitors (SCs) are energy storage devices that offer long life performances compared with conventional secondary batteries. In order to use SCs as main energy storage sources for spacecrafts, major challenges such as low energy densities, establishment of life performance tests, and large voltage variations due to charging/discharging must be overcome. Feasibility of SCs for spacecraft power subsystem was discussed based on experimental and analytical considerations.

JAXA is developing a Venus orbiter PLANET-C to be launched in 2010. This paper gives a summary of its power system and results of performance tests of the solar arrays and batteries. The solar arrays were confirmed to endure severe thermal cycles in the range of ?-170〜+170℃. The battery cells are subjected to simulation tests assuming practical operations, focusing on methods to control their deterioration.

Since electrical discharge development is very fast and influenced by the probability largely, strict condition control and high-resolution measurements are difficult. This paper describes numerical estimation of the sparkover voltages and time lag (V-t) characteristics utilizing a hydrodynamic numerical numerical modeling of a streamer and the equal-area criterion. V-t characteristics for a step voltage, a steep-front square voltage with a rise time of 20 ns, and 1.8/450 μs impulse voltage are successfully estimated using a single equal-area parameter obtained from the numerical modeling of the streamer. This suggests that a numerical estimation of V-t characteristics for any kinds of voltage wave form may be possible.