摘要
空间等离子体熵的不守恒可能来自于磁场位形改变和非绝热过程.熵参量PV^(5/3)被广泛应用于分析地球磁层等离子体片中的输运问题,其中,P为压力,V为单位磁通量管的体积.通过熵参量的分布和变化可以判断磁层的稳定性及揭示磁层中的动力学过程.本文利用地球磁层中熵参量的分析应用,计算了木星稳态磁层模型中磁通量管的熵参量分布.从5R_j(R_j为木星半径)到55_j,熵参量增加了4个量级,55 R)_j之后有所下降,表明所用磁层模型在55R_j之外已经不稳定.同时,假想磁场重联后的单位磁通量管的熵参量分布表明,赤道面中远磁尾的磁场重联是由尾向输运的磁力线管拉伸断裂重联引起的.
The nonconservation of entropy in space plasmas can result from magnetic reconfigura- tion as well as nonadiabatic processes such as plasma transport and energy transport. The theory of plasma transport in Earth＇s plasma sheet depends critically on the entropy parameter PV5/3, where P is particle pressure and V is the volume of a closed flux tube containing one unit of mag- netic flux. The stability and dynamics of the magnetosphere could be indicated by the change of entropy parameter. This paper shows the distribution of entropy parameter in the Jupiter＇s stable magnetosphere model using the analysis method in Earth＇s plasma sheet. The entropy parameter increases by four order of magnitudes quickly between 5 Rj and 55 Rj and then decline slowly. The result shows that the magnetosphere is unstable beyond 55 Rj. The paper also shows the contour of the entropy parameter after the fictitious magnetic reconnection. It points out that the reconnection near the equatorial plane is caused by the rupture and reeonnection of the flux tube which transports tailward.
出处
《空间科学学报》
CAS
CSCD
北大核心
2013年第5期465-472,共8页
Chinese Journal of Space Science
基金
国家自然科学基金项目(41074118
40890163
41121003)
中国科学院重点研究项目(KZZD-EW-01-4)
中国科学院知识创新项目(KZCX2-EW-QN50)共同资助
关键词
木星
磁层
熵参量(PV^5/3)
重联
Jupiter, Magnetosphere, Entropy parameter （PV5/3）, Reconnection
