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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), Spacecrafts operated the outside of geo magnetosphere are irradiated solar protons directly. Therefore, it is important to investigate the charging phenomenon of insulation materials under a proton beam irradiation. In this study, we focused on the internal charge accumulation during proton beam irradiation of insulation materials. We developed the electrode system to measure the charge distribution from the surface to the bulk of the sample. From the results, it observed that the amount of charge accumulation is larger 3.4 times than the results of using the general electrode system and the surface potential is 4.4 kV. These results suggest the possibility of discharge at the spacecraft operating environment., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA2030009008, レポート番号: JAXA-SP-20-007

第16回宇宙環境シンポジウム (2019年11月12日-13日. 東京都市大学横浜キャンパス), 横浜市, 神奈川県, The 16th Spacecraft Environment Symposium (November 12-13, 2019. Yokohama Campus, Tokyo City University), Yokohama, Kanagawa, Japan, Spacecraft are covered with MLI and OSR for protecting from the hard temperature differential in space environment and keeping the temperature inside of spacecraft. As the satellite are operated in the Van-Allen belt, those insulating materials are exposed by radio-active rays, such as electron and proton. Those charged particles are injected and accumulate in the bulk of materials. And it will be origin of electric static discharge (ESD). There phenomenon may lead to the satellite operation anomaly. Therefore, it is necessary to understand charging phenomena in the bulks of materials for spacecraft based on electronic physics, for reliabilities of long-life operation. In this research, we try to understand the charging phenomena on fluorinated polymer which are used for wire harness. Space charge accumulations in the bulk of the sample irradiated by an electron under DC application were studied using the pulsed electroacoustic (PEA) method., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1930014002, レポート番号: JAXA-SP-19-009

フッ素はエナメル質を強化し，う蝕予防に役立つことが知られている．またフッ素徐放性を有する歯冠修復材料は，二次う蝕予防に効果的だと言われている．本研究は自動pHサイクル装置を使用して，歯冠修復材料ならびにフッ化物処理がエナメル質に与える影響を明らかにし，脱灰溶液中に溶出する元素との相関について検討することを目的とした． 歯冠修復材料にはZ100（3M ESPE, USA），ビューティフィルII（BF : 松風，京都），フジIXGPエクストラカプセル（フジIX : ジーシー，東京）を使用した．ヒト大臼歯に各材料を充填したのちに切断し，薄型切片試料を作製した．その後，自動pHサイクル装置を使用し，試料を脱灰した．フッ化物処理は18.4 mMのNaF溶液に試料を１日１回５分間浸漬させて行った．材料周囲エナメル質のTransverse Microradiographyを撮影し，ΔIntegrated Mineral Loss（ΔIML）を求めた．また，各材料ブロックを作製し，脱灰溶液に浸漬させ，材料から溶出したフッ素とストロンチウムを定量した． フッ化物未処理群では２?４週においてBF群とフジIX群がZ100群と比較してΔIMLが有意に低かった．BF群とフジIX群の間には有意差が認められなかった．フッ化物処理群においても同様の傾向が認められた．フッ化物処理の有無で比較した場合，同一材料間では１週においてBF群ならびにフジIX群で有意差が認められた．フッ素とストロンチウムの溶出はBF群とフジIX群から認められ，両元素ともフジIX群からの溶出が有意に多かった．Z100群からは元素の溶出が認められなかった． また，材料からのフッ素とストロンチウムの溶出が確認できた歯冠修復材料周囲のエナメル質では，ΔIMLが有意に低くなった, Fluoride is known to be effective for prevention of dental caries by strengthening enamel. Fluoride releasing materials were expected as prevention for secondary caries. The purpose of this study is to evaluate the inhibitory effects of the restorative materials and fluoride treatment using an automatic pH-cycling system. In this study, we used the following three restorative materials ; Z100 (3M ESPE, USA), BEAUTIFIL Ⅱ (BF : Shofu, Tokyo), FUJI IX GP EXTRA CAPSULE (Fuji IX, GC, Tokyo). Extracted non-caries human molars were used. The specimens were filled with each material, and all specimens were repeated demineralization and remineralization using the automatic pH-cycling system for 1 to 4 weeks. Specimens were treated for 5 minutes every day with 18.4 mM NaF solution. Every each week, Δintegrated mineral loss (ΔIML) of the specimens was calculated from transverse microradiography images. Also, materials blocks immersed in demineralized solution for 1 to 4 weeks, and released elements from materials blocks were determined in demineralized solution. As a result, ΔIML of BF and FujiIX in which with and without fluoride treatment were significantly smaller than that of Z100 in 2 to 4 weeks. The significant difference was not recognized between BF and Fuji IX. The elements releasing from materials blocks, fluorine and strontium were measured from the BF and FujiIX , Fuji IX were released much these ions than the other materials. Z100 released no ions. In conclusion, ΔIML was reduced in ion releasing materials group, and it was suggested that the surface properties of the enamel was improved.