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電子がオーロライオノスフィアから離れて加速する電気場の時間的な進化
G T Marklund1, N Ivchenko, T Karlsson
1Division of Plasma Physics, Alfvén Laboratory, KTH, Royal Institute of Technology, SE 10044 Stockholm, Sweden. marklund@plasma.kth.se
Nature
|December 14, 2001
まとめ
明るいオーロラは,電子を加速する電場によって引き起こされます. 新しい衛星データは,上向きに加速するこれらの電子束がどのように形成され,進化し,可視的なオーロラディスプレイに影響を及ぼすかを明らかにしています.
科学分野:
- 宇宙物理学 宇宙物理学
- プラズマ物理学 プラズマ物理学
- 大気科学 大気科学
背景:
- 目に見えるオーロラは,上向きの電場によって加速された電子によるものです.
- 下向きの電場は,電子を地球から遠ざけて加速させ,これは予測されているが,完全に理解されていない現象である.
- この磁場と整合した電場をイオノスフィアで維持することは,科学的な議論の課題です.
研究 の 目的:
- 磁場と整合した電場の形成と振る舞いを調査する.
- イオノスフィアの上の電子加速の空間と時間のダイナミクスを理解するために.
- 目に見えるオーロラ現象におけるこれらの電場の役割を明確にするために.
主な方法:
- 協調的な測定を行うために,同一の計測器を備えた衛星の組成を利用した.
- 上向きの電場によって加速された観測された電子ビーム.
- 電気ポテンシャルと電流シートの構造と進化を分析した.
主要な成果:
- 約200秒間にわたって電位構造の大きさと幅の増大を記録した.
- 総電流が一定のままながら,下向き電流シートの同時拡大を観測した.
- 200秒のタイムスケールは,イオノスフィアからの電子の避難が,電場形成に役割を果たすことを示唆しています.
結論:
- 観測された電場進化は,イオノスフィアの電子脱出の役割を支持しています.
- このプロセスは,下向きの電流回路の負荷が増加することを意味します.
- この発見は,分断的なオーロラ・ディスプレイの理解に影響を与えるかもしれない.
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