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Frozen-in Condition

E+V×B=0

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3. Solar Wind and Interplanetary Magnetic Field

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Outline:

太阳风的发现 太阳风的特性 太阳风的形成 太阳风传播的范围 1AU 处太阳风的测量 Coronal Magnetic field Interplanetary Magnetic Field Park Spiral and Heliospheric Current Sheet Corotating Interaction Region

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太阳风的发现

彗星中的双拖尾结构1. Diffused one is caused by

solar radiation pressure;2. The sharp one is caused by

solar wind.

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Solar Wind

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7

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Parker’s solar wind model (1958)

从磁流体理论出发； 假设太阳大气层存在

一个加热源； 得到 supersonic solar

wind.

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Solar coronal outflow

假设日冕处于平衡态即受重力场约束 连续性方程

流体的运动方程Vlasov equation 流体的能量方程

0

vt

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Fluid momentum equation

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Interstellar wind

The majority of the interstellar gas and dust that we

see was produced by star death

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Solar Coronal Outflow

02 nvrdr

d

dr

dp

nmr

GM

dr

dvv

i

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理论预言的太阳风速率变化

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Flux conservation

行星际中的磁场

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太阳自转的影响

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实际的行星际磁场的传播

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太阳风如何被减速 ?

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Interstellar wind and background pressure

about 10-13Pa

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Solution: introducing a standing shock wave

Total pressure balanced at the shock front

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注意如下关系式

vdfkn

mT 3

3vvvvv bb

2

2

2exp

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v

v

v

nvf

k

vmT

2

2

22

2

212 vmnvnkTp th

2/22 vvth

k

mv

k

vmT th

22

2

定义：

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Voyager 1 和 2 的发现

Voyager 1 crossed the termination shock, September 23, 2005

Voyager 2 crossed the termination shock, August 30, 2007

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Termination of the Solar wind

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Voyager spacecraft

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Voyager mission

Voyager mission

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Solar wind at 1AU

Solar wind is fully ionized into electrons, protons, and He2+(3%);

Solar wind parameters measured by spacecraft near the Earth

  Fast wind Slow wind

Velocity 500-800 km/s 250-400 km/s

Density 3x106 m-3 10x106 m-3

Proton temperature 2x105 K 4x104 K

Electron temperature 1.2x105 1.5x105 K

Magnetic field 2-10 nT 2-10 nT

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WIND and ACE mission

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Lagrangian point

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Quiz 4

1.如果没有太阳风的直接测量，请问有什么自然现象支持太阳风的存在？列举两种以上。

2.说说源自太阳赤道上和太阳极区的磁场有什么差别，哪一种随日球层距离下降的快？

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Coronal Magnetic Field

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Interplanetary Magnetic Field

Introduction of Space Physics by M. G. Kivelson and C. T. Russell

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Parker Spiral magnetic field

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Image courtesy J. Jokipii, University of Arizona

行星际中性电流片

The radial current in the circuit is on the order of 3×109 amperes. However, the maximum current density is 10-10A/m2

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Heliospheric Current Sheet (HCS)

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Corotating Interaction Region

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Corotating Interaction Region shock

40http://www.physics.usyd.edu.au/~cairns/teaching/lecture11/node4.html

MHD 模拟的 CIRs

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Summary

简单介绍了太阳风经典理论； 探讨了太阳风在 Termination Shock 的减速

问题 ; Parker Spiral 行星际磁场 , 中性电流片 ,CIR ；

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