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Minimum energy state and minimum angle rotation of the magnetic field in a current sheet with sheared magnetic field
http://hdl.handle.net/2261/38134
4053e151-2e3d-4d08-96d9-49d03a051f14
名前 / ファイル | ライセンス | アクション | |
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Item type | 学術雑誌論文 / Journal Article(1) | |||||
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公開日 | 2016-12-28 | |||||
タイトル | ||||||
タイトル | Minimum energy state and minimum angle rotation of the magnetic field in a current sheet with sheared magnetic field | |||||
言語 | ||||||
言語 | eng | |||||
キーワード | ||||||
主題 | current sheet | |||||
主題Scheme | Other | |||||
キーワード | ||||||
主題 | discontinuities | |||||
主題Scheme | Other | |||||
キーワード | ||||||
主題 | self-organization | |||||
主題Scheme | Other | |||||
キーワード | ||||||
主題 | helicity | |||||
主題Scheme | Other | |||||
キーワード | ||||||
主題 | force-free magnetic field | |||||
主題Scheme | Other | |||||
キーワード | ||||||
主題 | minimum energy state | |||||
主題Scheme | Other | |||||
資源タイプ | ||||||
資源 | http://purl.org/coar/resource_type/c_6501 | |||||
タイプ | journal article | |||||
著者 |
Miura, Akira
× Miura, Akira |
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著者所属 | ||||||
著者所属 | Department of Earth and Planetary Physics, University of Tokyo | |||||
抄録 | ||||||
内容記述タイプ | Abstract | |||||
内容記述 | In order to answer why and how “the minimum angle rotation of the magnetic field” is realized in a current sheet with a sheared magnetic field, Taylor's helicity constraint, which is valid for low-β plasmas, is applied to a one-dimensional planar current sheet with a sheared magnetic field. A single constant helicity is defined for the total rectangular volume surrounding the current sheet and is shown to be gauge-invariant. The minimization of the magnetic energy with the constraint of the constant total helicity shows that the field is described by the constant α force-free equation and that the current sheet is a special class of tangential discontinuities with a constant field strength, or a “perpendicular rotational discontinuity.” The total rotational angle of the magnetic field across the current sheet is proportional to the ratio of the total magnetic energy/helicity in the force-free state. It is proposed that among an infinite number of force-free states the current sheet relaxes into a unique force-free state with the absolute minimum ratio of energy/helicity and thus into the absolute minimum energy state for a given constant helicity. Therefore, in the relaxed state the total rotational angle of the magnetic field across the current sheet is minimum and less than 180°. Although the present study of the relaxed state is applicable only to a tangential discontinuity, a qualitative resemblance of the model prediction with observations in situ and simulations of quasi-perpendicular rotational discontinuities suggests that the observed minimum angle rotation of the magnetic field in a current sheet with a sheared magnetic field is an emergence of plasma relaxation or self-organization in space plasmas. | |||||
書誌情報 |
Journal of geophysical research. A 巻 107, 号 7, p. 1143, 発行日 2002-07 |
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ISSN | ||||||
収録物識別子タイプ | ISSN | |||||
収録物識別子 | 01480227 | |||||
書誌レコードID | ||||||
収録物識別子タイプ | NCID | |||||
収録物識別子 | AA10819721 | |||||
DOI | ||||||
関連識別子 | ||||||
識別子タイプ | DOI | |||||
関連識別子 | info:doi/10.1029/2001JA009177 | |||||
権利 | ||||||
権利情報 | copyright 2002 by the American Geophysical Union | |||||
日本十進分類法 | ||||||
主題 | 450 | |||||
主題Scheme | NDC | |||||
出版者 | ||||||
出版者 | American Geophysical Union |