1. Magnetic Reconnection Rate and RHESSI Hard X-Ray Imaging Spectroscopy of Well Resolved X-class Flares Yan Xu, Ju Jing, Wenda Cao, and Haimin Wang

2. 2003 Oct. 29 X10 Red: NIR flare ribbons Blue: RHESSI HXR contours correspond to the 50 – 100 keV

4. Ding et al. 2003

5. According to Brown et al. 2002 Therefore, electrons with energy greater than 200 could reach 10 22 cm -2 Loop length ~ 10 9 cm, number density in corona ~ 10 11 cm -3 ==> N corona ~ 10 20 cm -2

6. Brown et al. 2002 More complicate treatment: N ~ , b…

7. We need more events…

8. DateContrast Enhancement (G-band) Peak HXR Flux (25 ~ 50 keV) Peak HXR Flux (50 ~ 100 keV) Position (Cosθ) 2003-Oct-29118%15260128000.92 2003-Nov-02230%*2338075000.49 2006-Dec-06336%446032000.45 2006-Dec-13104%340012000.89 2006-Dec-1484.5%20005400.69 G-band Observations

9. Footpoint Asymmetric e e α

10. e e α α   ? RHESSI Visibility + Forward-fit

11. Footpoint Asymmetric B   ?

12. Magnetic/Mirror Effect?  = - 2.80  = - 2.53  = - 2.72

13. Magnetic/Mirror Effect?  = - 2.74  = - 2.50  = - 2.60

14. Magnetic/Mirror Effect?

15. B (Gauss) Power Index

16. Shear Angle 20:40:5420:41:3220:41:4620:41:52 20:41:5820:42:0220:42:0820:42:18

17. Shear Angle 20:40:5420:41:3220:41:4620:41:52 20:41:5820:42:0220:42:0820:42:18

18. Shear Angle 20:41:3220:42:02

19. Shear Angle 20:41:3220:42:02 Change Rate vs. ???

20. G-band ~ E field ~ Power-index

21. Electric Field (V/cm) Contrast

22. G-band ~ E field ~ Power-index Electric Field (V/cm) Contrast

23. RHESSI Observations: Total Number of particles inside the acceleration region Rate of acceleration of electrons (from spatially-integrated HXR intensity) Specific Acceleration Rate Electron Acceleration Rate

24. Super-Dreicer Electric Field Acceleration (Somov 1991) B // BB E RHESSI observations ~ Vector Magnetograms