Magnetic Reconnection — Questions & Challenges

Presentation on theme: "Magnetic Reconnection — Questions & Challenges"— Presentation transcript:

1 Magnetic Reconnection — Questions & Challenges
Xiaogang Wang School of Physics, Peking University IFTS, Zhejiang University Sept , Suzhou, China

2 OUTLINE What we have known What we don’t know Possible answers
Brief summary

3 What we have known Hall effect physics Alfven frequency whistler waves
Quadruple field Fast reconnection rate 0.01 ~ 0.2VA Layer width of reconnecting field ~ di Electrical potential well on separatrix

4 What we have known In question
Layer length of reconnecting field ~ (diL)1/2 Reconnecting rate ~ (di/L)1/2 Electron density dip on separatrix (numerically observed) Lower hybrid oscillations (observed) Electron Alfven speed disturbance (observed)

5 What we have known 3D reconnection features
The existence of magnetic nulls (observed) Null-null line (Separator, observed) Spines and fans (observed) Lower hybrid waves on the separator (observed)

6 What we have known 3D reconnection features
Electron density peak on separator (observed) Electrical potential well on separator (observed) Langmuir oscillation near separator (observed)

7 What we don’t know 电子惯性区中的波动，特别是低杂波的激发与传播；
电子惯性区（包括分形线）中的密度sh上升？下降？ —— 原因及后果； 重联过程中的电子加热机制？ 电子Alfven波的存在？ Electron hole 的产生原因以及电子声波是否存在？

8 What we don’t know 电子压强梯度张量非对角项的贡献； 重联率的Scaling 的继续研究； 电子惯性是否对重联率有贡献？
Whistler or 离子波的贡献、观测及其与其他模式（比如LHW）的耦合？ 剪切流对重联结构和重联率的影响

9 What we don’t know Hall四极分布是否就是Whistler or Alfven频率whistler的驻波表现？
边界驱动对无碰撞磁重联的影响？

10 What we don’t know (3D) 3D重联中的Hall四极分布问题？ Separator上的电子加热机制及其与2D理论的对比？
Anti-parallel reconnection vs. Component reconnection (理论、观测上，对重联率的影响)?

11 What we don’t know (3D) Null以及Null-null line的产生机制（X-line不稳定导致null pair 产生是否是唯一机制）？ 3D重联的动力学理论（Theory of 3D reconnection dynamics） 单个Null与Null pair对重联发生和重联率大小的影响

12 Possible answers 应用回旋动力学理论研究电子压强梯度张量非对角项的贡献； 重联率Scaling 的实验研究；
双流体理论、回旋动力学理论中Whistler or Alfven频率whistler与其它模式（如LHW）的耦合； 剪切流及Alfven共振研究 边界驱动无碰撞磁重联研究（Hall MHD + Hybrid codes)

13 Possible answers Separator上的磁镜效应及电子加速与加热机制
Anti-parallel reconnection — Component reconnection：一个过程的两种表现形式；统计研究

14 SUMMARY Hall effects well understood Electron dynamics not
3D features getting attentions MHD & Magnetic reconnection FTP (PKU, ZJU, NAOC, USTC, DLUT)

15

16

17

18

19

20

21