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第17回宇宙環境シンポジウム (2020年10月7日-8日. 宇宙航空研究開発機構(JAXA)オンライン会議), The 17th Spacecraft Environment Symposium (October 7-8, 2020. Japan Aerospace Exploration Agency (JAXA), Online meeting), Recently, the operating voltage of electronic devices on spacecrafts tends to be weakly, and even a little electric potential fluctuation may cause malfunctions. Therefore, it is necessary to evaluate the electrical properties of insulating materials by focusing on electronic properties. In this study, we focus on the generation of electron-hole pairs, and we measured the amount of charges when the irradiated by electron beam at each flux using a new voltage application method with a vacuum capacitor., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA2030009010, レポート番号: JAXA-SP-20-007

第9回宇宙環境シンポジウム (2012年11月5日-6日. 東京都市大学・世田谷キャンパス), 東京, 9th Spacecraft Enivironment Symposium (November 5-6, 2012, Setagaya Campus, Tokyo City University), Tokyo Japan, Spacecraft are charged under plasma environment and radiation environment in space, and it may lead failures and anomalies of spacecraft when discharge on the spacecraft surface occurs. One of the most important surface materials is cover glass for solar-cells which is a source of an electrical power. The purpose of this paper is to investigate surface-potential characteristics of coverglasses with coatings after electron irradiation. We found that the surface potential on coverglasses becomes positive within a few hours after irradiation. Comparing the surface potential histories of coated coverglass and silica glass revealed that the positive potential of coverglass is due to ionization of metallic atoms in surface coating material. The positive potential is relaxed over several days which will increase a risk of discharge. We conclude it is necessary to select coating materials with lower secondary emission coefficient., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA0061891025, レポート番号: JAXA-SP-12-017

第9回宇宙環境シンポジウム (2012年11月5日-6日. 東京都市大学・世田谷キャンパス), 東京, 9th Spacecraft Enivironment Symposium (November 5-6, 2012, Setagaya Campus, Tokyo City University), Tokyo Japan, We studied how to measure the secondary electron emission (SEE) of metal and insulating materials used for satellite thermal insulation or other such purposes. SEE yield measurement is very important for analyzing charge accumulation on the satellite surfaces due to the space environment because electron emission for irradiated electrons influences the amount of surface charge. Therefore, we are developing the measurement system without the deceleration voltage and enable to obtain the characteristics of the SEE yield from insulation materials irradiated by an electron beam with energy of 200 eV to 10 keV. This report introduces the developed measurement system and the SEE yield measurement results of metal sample and polymer. From those results, we discuss the characteristics of SEE that depend on each material. Furthermore, we also propose a future plan of SEE measurement for satellite materials., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA0061891022, レポート番号: JAXA-SP-12-017

第8回宇宙環境シンポジウム (2011年10月18-19日. 東京国際展示場), 東京, 8th Spacecraft Enivironment Symposium (October 18-19, 2011, Tokyo Big Sight), Tokyo Japan, Spacecrafts are charged under plasma environment and radiation environment in space, and it may lead failures and anomalies of spacecrafts when discharge on the spacecraft surface occurs. One of the most important surface materials is cover glass for solar-cells which is a source of an electrical power. The purpose of this paper is to investigate surface-potential characteristics of cover glasses with coatings after electron irradiation. We found that the surface potential on cover glasses becomes positive within a few hours after irradiation. Comparing the surface potential histories of coated cover glass and silica glass revealed that the positive potential of cover glass is due to ionization of metallic atoms in surface coating material. The positive potential is relaxed over several days which will increase a risk of discharge. We conclude it is necessary to select coating materials difficult to ionization by charged particles., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA0065159018, レポート番号: JAXA-SP-11-012

第8回宇宙環境シンポジウム (2011年10月18-19日. 東京国際展示場), 東京, 8th Spacecraft Enivironment Symposium (October 18-19, 2011, Tokyo Big Sight), Tokyo Japan, The purpose of this study is to build and validate a model of volume resistivity from the experimental results to analyze the influence of parameters such as electron beam energy and sample temperature. We established a measurement setup, called the charge storage method, which measures volume resistivity by analyzing the time history of a dielectric devices to investigate volume resistivity in the temperature range attained (from 260K to 320K). In this paper, we measured the volume resistivity. We analyzed the effect of sample thickness, electron beam irradiation energy and temperature. The dielectric material considered here is typical polyimide (Kapton(Reg. U.S.Pat. & Tm. Off.)) film. The experimental results indicate that higher electron energy and thinner sample thickness show lower resistivity .volume resistivity in dark current region decreases theoretically as the sample temperature increases. Moreover, we proposed the mechanism of charge accumulation in charge storage method., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA0065159019, レポート番号: JAXA-SP-11-012

Electrical charge accumulation characteristics in dielectric materials for a spacecraft panel have studied for understanding of spacecraft charging problem in high energy radiation environment. This study especially has focused on a spacecraft charging accident caused by internal charge accumulation in dielectric materials irradiated by proton beam. The internal charge accumulation of those bulks measurement was carried out using PEA (Pulsed Electro-Acoustic) method. As the results, we obtained a positive charge accumulation in the bulk of samples after proton beam irradiation. However, it was not observed a positive charge accumulation that a quartz glass has an Al evaporated layer on the surface of proton beam irradiation side. Therefore, in this paper, we compare between the PEA's internal charge measurement results and energy band model because of we discus the charge formation mechanism in the bulk irradiated by proton beam. Furthermore, we studied how to measure the secondary electron emission (SEE) of metal and insulating materials used for satellite thermal insulation or other such purposes. SEE yield measurement is very important for analyzing charge accumulation on the satellite surfaces due to the space environment because electron emission. Therefore, we tried to measure the SEE yield. In this report, we introduce the SEE yield measurement results of reference materials (Au, Ag and Quartz glass) and insulating materials. From those results, we discuss the characteristics of SEE that depend on each material., 資料番号: AA0049500035, レポート番号: JAXA-SP-06-006

A new measurement method for volume resistivity of dielectric material has been tested and compared to the standard ASTM (American Society for Testing and Materials) 'capacitor method'. This is intended for obtaining resistivity values of highly insulated material for spacecraft surface under realistic condition which simulates vacuum and electron beam irradiation. The resistivity value is calculated from exponential decay time constant of surface potential after electron beam irradiation ceased. The results show that the resistivity value from present method is 10(exp 3) times larger than that obtained from capacitor method. This indicates that charged dielectrics need much longer field relaxation time which would cause reconsideration of current spacecraft design guideline and charge analysis., 資料番号: AA0063997016, レポート番号: JAXA-SP-07-030