{"title":"轴上具有高电流密度的无力磁通绳","authors":"A. A. Solov’ev","doi":"10.1134/S1063772924700550","DOIUrl":null,"url":null,"abstract":"<p>A new model of a force-free magnetic flux rope with a high concentration of electric current on the axis is presented. The general property of axisymmetric force-free magnetic ropes is that with the exit of the top of the magnetic loop-rope into the corona, the external pressure that keeps it from lateral expansion steadily decreases, and with some critical decrease in this pressure, the longitudinal magnetic field of the rope becomes zero on the surface where the electric current changes its sign (it is current inversion surface—CIS). In this case, the force-free parameter <span>\\(\\alpha (r)\\)</span> and the azimuthal electric current <i>j</i><sub>ϕ</sub>(<i>r</i>) experience a second-order discontinuity on this surface, so that in the vicinity of CIS their values begin to increase without limit. The current (drift) speed of electrons here will inevitably exceed the speed of ion sound. This serves as a trigger for the heating of non-isothermal plasma (so it turns out <i>T</i><sub>e</sub> <span>\\( \\gg \\)</span> <i>T</i><sub>i</sub>) and the excitation of plasma ion-acoustic instability of the plasma not only near the CIS, but also in the central region of the rope, on its axis, where the current density is especially high. The appearance of anomalous resistance leads to rapid dissipation of the magnetic field and the generation of a super-Dreicer electric field. The Parker effect, associated with the equalization (with some delay) of the torque along the axis of the rope due to the transfer of the azimuthal field to the region of energy release, leads to quasiperiodic pulsations of hard flare radiation and, ultimately, ensures the flare release of the most part of free magnetic energy accumulated in the rope.</p>","PeriodicalId":55440,"journal":{"name":"Astronomy Reports","volume":null,"pages":null},"PeriodicalIF":1.1000,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Force Free Magnetic Flux Rope with a High Current Density on the Axis\",\"authors\":\"A. A. Solov’ev\",\"doi\":\"10.1134/S1063772924700550\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>A new model of a force-free magnetic flux rope with a high concentration of electric current on the axis is presented. The general property of axisymmetric force-free magnetic ropes is that with the exit of the top of the magnetic loop-rope into the corona, the external pressure that keeps it from lateral expansion steadily decreases, and with some critical decrease in this pressure, the longitudinal magnetic field of the rope becomes zero on the surface where the electric current changes its sign (it is current inversion surface—CIS). In this case, the force-free parameter <span>\\\\(\\\\alpha (r)\\\\)</span> and the azimuthal electric current <i>j</i><sub>ϕ</sub>(<i>r</i>) experience a second-order discontinuity on this surface, so that in the vicinity of CIS their values begin to increase without limit. The current (drift) speed of electrons here will inevitably exceed the speed of ion sound. This serves as a trigger for the heating of non-isothermal plasma (so it turns out <i>T</i><sub>e</sub> <span>\\\\( \\\\gg \\\\)</span> <i>T</i><sub>i</sub>) and the excitation of plasma ion-acoustic instability of the plasma not only near the CIS, but also in the central region of the rope, on its axis, where the current density is especially high. The appearance of anomalous resistance leads to rapid dissipation of the magnetic field and the generation of a super-Dreicer electric field. The Parker effect, associated with the equalization (with some delay) of the torque along the axis of the rope due to the transfer of the azimuthal field to the region of energy release, leads to quasiperiodic pulsations of hard flare radiation and, ultimately, ensures the flare release of the most part of free magnetic energy accumulated in the rope.</p>\",\"PeriodicalId\":55440,\"journal\":{\"name\":\"Astronomy Reports\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.1000,\"publicationDate\":\"2024-08-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Astronomy Reports\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://link.springer.com/article/10.1134/S1063772924700550\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Astronomy Reports","FirstCategoryId":"101","ListUrlMain":"https://link.springer.com/article/10.1134/S1063772924700550","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
摘要
摘要 介绍了轴上电流高度集中的无力磁通绳的新模型。轴对称无力磁通绳的一般特性是,随着磁环绳顶部进入电晕,使其不横向膨胀的外部压力逐渐减小,当该压力减小到某个临界值时,在电流符号改变的表面(即电流反转面-CIS)上,磁环绳的纵向磁场变为零。在这种情况下,无力参数(\alpha (r)\)和方位电流jj(r)在该表面上经历二阶不连续性,因此在CIS附近,它们的值开始无限制地增加。电子在这里的电流(漂移)速度将不可避免地超过离子声速。这将引发非等温等离子体的加热(事实证明 Te \( \gg \) Ti)以及等离子体离子声不稳定性的激发,不仅在 CIS 附近,而且在绳索的中心区域,在其轴线上,这里的电流密度特别高。反常电阻的出现导致磁场迅速耗散,并产生超德雷克电场。帕克效应与由于方位磁场转移到能量释放区域而导致的沿绳索轴线的扭矩均衡(有一定的延迟)有关,导致硬耀斑辐射的准周期脉动,并最终确保在绳索中积累的大部分自由磁能的耀斑释放。
Force Free Magnetic Flux Rope with a High Current Density on the Axis
A new model of a force-free magnetic flux rope with a high concentration of electric current on the axis is presented. The general property of axisymmetric force-free magnetic ropes is that with the exit of the top of the magnetic loop-rope into the corona, the external pressure that keeps it from lateral expansion steadily decreases, and with some critical decrease in this pressure, the longitudinal magnetic field of the rope becomes zero on the surface where the electric current changes its sign (it is current inversion surface—CIS). In this case, the force-free parameter \(\alpha (r)\) and the azimuthal electric current jϕ(r) experience a second-order discontinuity on this surface, so that in the vicinity of CIS their values begin to increase without limit. The current (drift) speed of electrons here will inevitably exceed the speed of ion sound. This serves as a trigger for the heating of non-isothermal plasma (so it turns out Te\( \gg \)Ti) and the excitation of plasma ion-acoustic instability of the plasma not only near the CIS, but also in the central region of the rope, on its axis, where the current density is especially high. The appearance of anomalous resistance leads to rapid dissipation of the magnetic field and the generation of a super-Dreicer electric field. The Parker effect, associated with the equalization (with some delay) of the torque along the axis of the rope due to the transfer of the azimuthal field to the region of energy release, leads to quasiperiodic pulsations of hard flare radiation and, ultimately, ensures the flare release of the most part of free magnetic energy accumulated in the rope.
期刊介绍:
Astronomy Reports is an international peer reviewed journal that publishes original papers on astronomical topics, including theoretical and observational astrophysics, physics of the Sun, planetary astrophysics, radio astronomy, stellar astronomy, celestial mechanics, and astronomy methods and instrumentation.