{"created":"2021-03-01T06:17:19.448651+00:00","id":776,"links":{},"metadata":{"_buckets":{"deposit":"2c28744f-a670-493b-aae4-c6aa7982fa88"},"_deposit":{"id":"776","owners":[],"pid":{"revision_id":0,"type":"depid","value":"776"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00000776","sets":["75:121:122","9:10:11"]},"item_2_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2002-07","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"7","bibliographicPageStart":"1143","bibliographicVolumeNumber":"107","bibliographic_titles":[{"bibliographic_title":"Journal of geophysical research. A"}]}]},"item_2_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"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.","subitem_description_type":"Abstract"}]},"item_2_publisher_20":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"American Geophysical Union"}]},"item_2_relation_11":{"attribute_name":"DOI","attribute_value_mlt":[{"subitem_relation_type_id":{"subitem_relation_type_id_text":"info:doi/10.1029/2001JA009177","subitem_relation_type_select":"DOI"}}]},"item_2_rights_12":{"attribute_name":"権利","attribute_value_mlt":[{"subitem_rights":"copyright 2002 by the American Geophysical Union"}]},"item_2_source_id_10":{"attribute_name":"書誌レコードID","attribute_value_mlt":[{"subitem_source_identifier":"AA10819721","subitem_source_identifier_type":"NCID"}]},"item_2_source_id_8":{"attribute_name":"ISSN","attribute_value_mlt":[{"subitem_source_identifier":"01480227","subitem_source_identifier_type":"ISSN"}]},"item_2_subject_15":{"attribute_name":"日本十進分類法","attribute_value_mlt":[{"subitem_subject":"450","subitem_subject_scheme":"NDC"}]},"item_2_text_4":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"Department of Earth and Planetary Physics, University of Tokyo"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Miura, Akira"}],"nameIdentifiers":[{"nameIdentifier":"2980","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2017-05-30"}],"displaytype":"detail","filename":"JGR_A107_NA07_01143.pdf","filesize":[{"value":"148.8 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"JGR_A107_NA07_01143.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/776/files/JGR_A107_NA07_01143.pdf"},"version_id":"d65087f0-cf32-419c-8917-7cc18dc0f32d"}]},"item_keyword":{"attribute_name":"キーワード","attribute_value_mlt":[{"subitem_subject":"current sheet","subitem_subject_scheme":"Other"},{"subitem_subject":"discontinuities","subitem_subject_scheme":"Other"},{"subitem_subject":"self-organization","subitem_subject_scheme":"Other"},{"subitem_subject":"helicity","subitem_subject_scheme":"Other"},{"subitem_subject":"force-free magnetic field","subitem_subject_scheme":"Other"},{"subitem_subject":"minimum energy state","subitem_subject_scheme":"Other"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"journal article","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"Minimum energy state and minimum angle rotation of the magnetic field in a current sheet with sheared magnetic field","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Minimum energy state and minimum angle rotation of the magnetic field in a current sheet with sheared magnetic field"}]},"item_type_id":"2","owner":"1","path":["11","122"],"pubdate":{"attribute_name":"公開日","attribute_value":"2016-12-28"},"publish_date":"2016-12-28","publish_status":"0","recid":"776","relation_version_is_last":true,"title":["Minimum energy state and minimum angle rotation of the magnetic field in a current sheet with sheared magnetic field"],"weko_creator_id":"1","weko_shared_id":null},"updated":"2022-12-19T03:41:49.424435+00:00"}