首页|火星感应磁层边界不稳定性研究:K-H波及其产生的磁通量绳

火星感应磁层边界不稳定性研究:K-H波及其产生的磁通量绳

扫码查看
原文链接
  • 万方数据
  • 维普
火星感应磁层边界的等离子体不稳定性,如边界层处速度剪切激发的Kelvin-Helmholtz(K-H)不稳定性,对火星感应磁层结构和磁层离子输运过程具有重要的影响.本文利用Mars Atmosphere and Volatile EvolutioN(MAVEN)卫星搭载的 Magnetometer(MAG)和 Super Thermal and Thermal Ion Composition(ST ATI C)仪器所提供的磁场和等离子数据,分析了 2018年5月21日火星感应磁层边界处观测到的K-H不稳定性事件,发现在磁场、重离子通量、离子成分与密度、和离子速度上存在五个连续的准周期变化,估算K-H波的周期为～100 s,同时在其中两个K-H涡旋内发现了磁通量绳结构.磁通量绳的轴向方向与边界层法向准垂直,且其中的离子成分与涡旋内电离层等离子体成分接近,表明此处的磁通量绳有可能是在K-H波的发展过程中形成.磁通量绳的整体速度也远大于此处的离子逃逸速度,这可能导致重离子O+和O2+从火星大气中快速逃逸.
Study on the instability in Mars'induced magnetospheric boundary:Kelvin-Helmholtz waves and associated magnetic flux ropes
The plasma instabilities in Mars'induced magnetospheric boundary such as the Kelvin-Helmholtz(K-H)instability induced by velocity shear,significantly affect the structure of Mars'induced magnetosphere and the transport of ions within the Martian magnetosphere.In this study,using the magnetic field and plasma data provided by the Magnetometer(MAG)and Super Thermal and Thermal Ion Composition(STATIC)instruments onboard the Mars Atmosphere and Volatile EvolutioN(MAVEN)spacecraft,we analyze the K-H instability events observed at the induced magnetospheric boundary on May 21,2018.We identify five consecutive quasi-periodic variations in the magnetic field,heavy ion flux,ion composition and density,and ion velocity.The estimated period of the K-H waves is approximately 100 seconds.Furthermore,we observe magnetic flux rope structures within two of the K-H vortices.The axial direction of the magnetic flux rope is nearly perpendicular to the normal of the boundary layer,and its ion composition is similar to that of the ionospheric plasma within the vortices.This indicates that the magnetic flux rope in this region is likely formed during the development of Kelvin-Helmholtz waves.The overall velocity of the magnetic flux rope is much greater than the ion escape velocity in this region,which could result in the rapid escape of heavy ions 0+and O2+from the Martian atmosphere.

K-H instabilityMagnetic flux ropesAtmospheric escape

吴放、葛亚松、黄灿、王磊、杜爱民

展开 >

中国科学院地质与地球物理研究所,中国科学院深地资源装备技术工程实验室,北京 100029

中国科学院地球科学研究院,北京 100029

中国科学院大学地球与行星科学学院,北京 100049

K-H不稳定性 磁通量绳 大气逃逸

国家自然科学基金国家自然科学基金国家自然科学基金国家自然科学基金国家自然科学基金国家自然科学基金国家自然科学基金中国科学院先导B计划民用航天预研项目民用航天预研项目民用航天预研项目民用航天预研项目

42330207422742224218810142025404419741864217418841674163XDB41000000D020303D020308D020103D020104

2024

10.6038/cjg2023R0379

地球物理学报
中国地球物理学会 中国科学院地质与地球物理研究所

地球物理学报

CSTPCD北大核心
影响因子：3.703
ISSN：0001-5733
年,卷(期)：2024.67(9)