Entropy Parameter of Jupiter’s Magnetosphere
-
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PV5/3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5Rj(Rj为木星半径)到55Rj,熵参量增加了4个量级,55Rj之后有所下降,表明所用磁层模型在55Rj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.
-
关键词:
- 木星 /
- 磁层 /
- 熵参量 (PV5/3) /
- 重联
Abstract: The nonconservation of entropy in space plasmas can result from magnetic reconfiguration 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 magnetic 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 5Rj and 55Rj and then decline slowly. The result shows that the magnetosphere is unstable beyond 55Rj. 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 reconnection of the flux tube which transports tailward.-
Key words:
- Jupiter /
- Magnetosphere /
- Entropy parameter (PV5/3) /
- Reconnection
-
[1] Baumjohann W, Paschmann G, Lühr H. Characteristics of high-speed ion flows in the plasma sheet[J]. J. Geophys. Res., 1990, 95: 3801-3801 [2] Wolf R A, Kumar V, Toffoletto F R, et al. Estimating local plasma sheet PV5/3 from single-spacecraft measurements[J]. J. Geophys. Res., 2006, 111, A12218 [3] Wolf R A, Wan Y F, Xing X, et al. Entropy and plasma sheet transport[J]. J. Geophys. Res., 2009, 114, A00D00 [4] Chen C X, Wolf R A. Theory of thin-filament motion in Earth's magnetotail and its application to bursty bulk flows[J]. J. Geophys.Res., 1999, 104:14613 [5] Bernstein I B, Frieman E A, Kruskal M D, et al. An energy principle for hydromagnetic stability problems[J]. Proc. R. Soc., 1958, A244:17-20 [6] Grodent D, Clarke J T, Waite J H, et al. Jupiter's polar auroral emissions[J]. J. Geophys. Res., 2003, 108:1366 [7] Chen C X. Numerical simulation of the Io-torus-driven radial plasma transport[J]. J. Geophys. Res., 2003, 108(A10):1376-1382 [8] Wing S, Johnson J R. Introduction to special section on entropy properties and constraints related to space plasma transport[J]. J. Geophys. Res., 2010, 115, A00D00 [9] Caudal G D. A self-consistent model of Jupiter's magnetodisc including the effects of centrifugal force and pressure[J]. J. Geophys. Res., 1986, 91:4201-4221 [10] Hill T W. Inertial limit on corotation[J]. J. Geophys. Res., 1979, 84: 6554 [11] Lackner K. Deformation of a magnetic dipole field by trapped particles[J]. J. Geophys. Res., 1970, 75: 3180-3192 [12] Siscoe G L, Summers D. Centrifugally driven diffusion of Iogenic plasma[J]. J. Geophys. Res., 1981, 86: 8471-8479 [13] Mauk B H, Gary S A, Kane M, et al. Hot plasma parameters of Jupiter's inner magnetosphere[J]. J. Geophys. Res., 1996, 101: 7685-7695 [14] Mauk B H, McEntire R W, Willians D J, et al. Properties of Ganymede's magnetosphere as revealed by energetic particle observations[J]. J. Geophys. Res., 1998, 103(A8), doi: 10.1029/98JA01370 [15] Bagenal F. Empirical model of the Io plasma torus: Voyager measurements[J]. J. Geophys. Res., 1994, 99: 11043-11062 -
-
计量
- 文章访问数: 2340
- HTML全文浏览量: 62
- PDF下载量: 1330
-
被引次数:
0(来源:Crossref)
0(来源:其他)
下载:
