@inproceedings{oai:jaxa.repo.nii.ac.jp:00006336, author = {下田, 忠宏 and 町田, 忍 and 向井, 利典 and 斎藤, 義文 and 笠羽, 康正 and 早川, 基 and Shimoda, Tadahiro and Machida, Shinobu and Mukai, Toshifumi and Saito, Yoshifumi and Kasaba, Yasumasa and Hayakawa, Hajime}, book = {宇宙航空研究開発機構特別資料, JAXA Special Publication: 9th Spacecraft Charging Technology Conference}, month = {Aug}, note = {In the Earth's magnetosphere where the spacecraft potential is usually positive, photoelectrons emitted from the spacecraft surface are attracted back to the spacecraft and some of them are detected by electron analyzer onboard. Then photoelectrons are unnecessary contamination. By analyzing such a component detected by LEP/EA-e onboard GEOTAIL spacecraft, we examined velocity/energy distribution functions of photoelectrons, and their relationship to the spacecraft potential. We found that the ratio of the duskward photoelectron flux to the dawnward flux increases when the spacecraft potential is large, and decreases when it is small. Further analysis revealed, by plotting the ratio as a function of the photoelectron energy normalized by the spacecraft potential (E/V(sub sc)), that it is the largest when E/V(sub sec) is about one third. This result implies the existence of azimuthal component of electric field as well as the radial component which is regarded to be dominant in an ordinary case around the spacecraft surface, although it is not clear why such an electric field is generated around GEOTAIL., 資料番号: AA0049206021, レポート番号: JAXA-SP-05-001E}, pages = {155--160}, publisher = {宇宙航空研究開発機構, Japan Aerospace Exploration Agency (JAXA)}, title = {Asymmetry of photoelectron distribution and its dependence on spacecraft potential obtained from GEOTAIL data}, volume = {JAXA-SP-05-001E}, year = {2005} }