教師資料查詢 | 類別: 會議論文 | 教師: 汪愷悌 WANG KAITI (瀏覽個人網頁)

標題:Generation of anisotropic electron distributions in the Earth's magnetosphere
學年104
學期2
發表日期2016/06/27
作品名稱Generation of anisotropic electron distributions in the Earth's magnetosphere
作品名稱(其他語言)
著者Tohru Hada; Wang, Kaiti
作品所屬單位
出版者
會議名稱18th International Congress on Plasma Physics
會議地點Kaohsiung, Taiwan
摘要Anisotropic electron distributions are often found in the earth’s magnetotail, in the energy range from about 10eV to 10keV [1-3]. Theoretical models are proposed to account for these distributions, based on parallel (Fermi) and perpendicular (betatron) electron heating due to deformation of the magnetic field lines [1]. Recently, Wang et al. (2014) made a statistical analysis of the variation of the electron pitch-angle anisotropies during geomagnetic dipolarization events using THEMIS data [3]. They found that, after the dipolarization, pancake type (perp temperature > parallel) anisotropy increases when the electron energy E < ~1keV, while cigar type (perp < parallel) anisotropy dominates for E>~1keV. When typical parameters are used for the magnetic field and the electron energy, the first adiabatic invariant is always conserved while the second invariant (action associated with the mirroring motion) can be violated depending on the electron energy. When both the first and the second invariants are conserved, types of anisotropy produced by compression of the field depend only on the shape of the magnetic field configuration. If the field remains dipolar, pancake type will be produced. If the magnetic field lines are stretched like those in the magnetotail, cigar-type anisotropy will be produced, since compression (earthward motion) of the field reduces the field line length without much changing the field strength. In this presentation we show our results of test particle simulations to discuss what types of pitch-angle anisotropies would emerge for various field line configurations. In particular, we show that the observed dependence of the types of anisotropies on the electron energy can roughly be explained in the present model.
關鍵字
語言英文
收錄於
會議性質國際
校內研討會地點
研討會時間20160627~20160701
通訊作者Tohru Hada
國別中華民國
公開徵稿
出版型式
出處Book of Abstracts, ICPP 2016, pp.C1P1-5
相關連結
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