Frozen-in Condition
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Transcript of Frozen-in Condition
1
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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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
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2
212 vmnvnkTp th
2/22 vvth
k
mv
k
vmT th
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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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