| 著者名 | Authors | 所属機関名 | 所属機関名(欧文) | |
| 1 | #星野/真弘 | Hoshino/M | 宇宙科学研究所 | Institute of Space and Astronautical Science |
| 2 | 向井/利典 | Mukai/T | 宇宙科学研究所 | Institute of Space and Astronautical Science |
| 3 | 篠原/育 | Shinohara/I | 宇宙科学研究所 | Institute of Space and Astronautical Science |
| 4 | 斎藤/義文 | Saito/Y | 宇宙科学研究所 | Institute of Space and Astronautical Science |
| 5 | 國分/征 | Kokubun/S | 名古屋大学・太陽地球環境研究所 | Solar-Terrestrial Environment Laboratory, Nagoya University |
講演予稿:
磁気リコネクション現象に伴って磁気圏尾部で観測されるプラズマシートには、しばしば２つの異なったプラズマ
領域が存在する。内側のプラズマシートは、弱い磁場と等方的なプラズマで満たされており、一方外側の
プラズマシートは、ローブと内側プラズマシートとの中間的な磁場の強さをもち、プラズマは温度異方性を示す。
磁場に平行方向の温度のが垂直方向よりも高い。ジオテイル衛星のデータ解析により、２つのプラズマシートが、
スロー衝撃波によって加速加熱されたプラズマと、磁気リコネクションのX点近傍で加熱されたプラズマで
支配されていることを議論する。
abstract:
Understanding magnetic reconnection is the key to resolving a number of critical questions in magnetosphereic physics, solar physics, and general plasma physics. More than 35 years ago Petschek proposed an innovation idea of a magnetic reconnection model to explain explosive energy release of solar flares. The Petschek model has been applied for many applications of magnetic reconnection phenomena, and most of reconnection studies are now based on the concept of Petschek reconnection model. Two pairs of slow mode shocks play an important role on a sudden energy release and on a formation of plasma sheet with high density and hot plasmas. It is assumed that uniform plasma density and uniform plasma temperature is filled in the slow shock downstream.
The slow shock transitions observed by the satellites, however, contain the complicated structures, which are not described by a simple slow shock transition. If the Petschek-type slow shock is formed in the magnetotail, the x-component of the magnetic field must vanish in the slow shock downstream region due to the symmetry structure against the x-axis. The observed x-component of the magnetic field, however, is not weak in the downstream of the lobe boundary. Moreover, in addition to the slow shock boundary identified observationally using by the Rankine-Hugoniot slow shock condition, another discontinuity in the slow shock downstream region is often observed in the distant magnetotail. The magnitude
of the magnetic field becomes almost zero across the second discontinuity. Since these two different regions are often observed in the distant magnetotail by the Geotail observation, this structure seems to be stable in dynamic time scale of the plasma sheet evolution.
In this presentation, we study the structures of the above two discontinuities. We conclude that the slow shock downstream contains a contact discontinuity which separates the slow shock heated plasmas from the hot plasmas supplied from an X-type region.
キーワード:
プラズマシート、磁気リコネクション、磁気圏、遅進衝撃波
Keywords:
plasma sheet, magnetic reconnection, magneotail, slow-mode shock waves