Intermittent thermal plasma acceleration linked to sporadic motions of the magnetopause, first Cluster results
Intermittent thermal plasma acceleration linked to sporadic motions of the magnetopause, first Cluster results
复制标题
间歇性热等离子体加速与磁层顶的零星运动有关，第一个集群结果
DOI：
10.5194/angeo-19-1523-2001
复制
发表时间：
2001
影响因子：
1.9
通讯作者：
M. McCarthy
中科院分区：
文献类型：
--
作者：
J. Sauvaud;R. Lundin;H. Rème;J. Mcfadden;C. Carlson;G. Parks;E. Möbius;L. Kistler;B. Klecker;E. Amata;A. M. DiLellis;V. Formisano;J. Bosqued;I. Dandouras;P. Décréau;M. Dunlop;L. Eliasson;A. Korth;B. Lavraud;M. McCarthy
本文提出了对非常密集的热电离层离子（H + 、He + 、O + ）群的首次观测，这些离子群在邻近磁层顶及其磁层一侧的区域中垂直于局部磁场进行局部“加速”。观测周期是在长期非常弱的磁活动之后进行的。在所呈现的情况下，磁层顶的循环运动出乎意料地与能量在 5 eV 至 ~1000 eV 范围内的电离层离子的循环能量结构的闭合场线内的出现相关。最重的离子具有最高的能量。这里，离子行为被解释为局部电场增强/减弱的结果，其绝热增强/降低局部致密热离子群的体能。这种漂移效应与压力变化引起的磁层顶运动直接相关，允许热离子克服卫星电势并被超热 CIS 簇实验检测到。当快速流动时，即可检测时，这些来自陆地的离子的密度（~ 1 cm -3 ）（在此处介绍的情况下）大大高于来自磁层/等离子体片的离子的局部密度，这再次提出了即使在非常安静的磁场条件下太阳和电离层源对于磁层等离子体的相对重要性的问题。
This paper presents the first observations with Cluster of a very dense population of thermal ionospheric ions (H + , He + , O + ) locally "accelerated" perpendicularly to the local magnetic field in a region adjacent to the magnetopause and on its magnetospheric side. The observation periods follow a long period of very weak magnetic activity. Recurrent motions of the magnetopause are, in the presented cases, unexpectedly associated with the appearance inside closed field lines of recurrent energy structures of ionospheric ions with energies in the 5 eV to ~1000 eV range. The heaviest ions were detected with the highest energies. Here, the ion behaviour is interpreted as resulting from local electric field enhancements/decreases which adiabatically enhance/lower the bulk energy of a local dense thermal ion population. This drift effect, which is directly linked to magnetopause motions caused by pressure changes, allows for the thermal ions to overcome the satellite potential and be detected by the suprathermal CIS Cluster experiment. When fast flowing, i.e. when detectable, the density (~ 1 cm -3 ) of these ions from a terrestrial origin is (in the cases presented here) largely higher than the local density of ions from magnetospheric/plasma sheet origin which poses again the question of the relative importance of solar and ionospheric sources for the magnetospheric plasma even during very quiet magnetic conditions.