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Magnetotail Current Sheet IKI 26-30 September 2011 Magnetic Reconnection in the Current Sheet:

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Magnetotail Current Sheet IKI 26-30 September 2011 Magnetic Reconnection in the Current Sheet: Geotail Observations Wednesday 28 September 2011, 1220-1300 T. Nagai Tokyo Institute of Technology. The basic physical components on the magnetic reconnection site

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Magnetotail Current Sheet IKI 26-30 September 2011 Magnetic Reconnection in the Current Sheet:
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  1. Magnetotail Current Sheet IKI 26-30 September 2011 Magnetic Reconnection in the Current Sheet: Geotail Observations Wednesday 28 September 2011, 1220-1300 T. Nagai Tokyo Institute of Technology

  2. The basic physical components on the magnetic reconnection site • The central electron current layer – the (electron) diffusion region • The ion-electron decoupling region – the Hall physics region • Inflows and Outflows – the MHD region

  3. MHD Picture of Magnetic Reconnection inflow outflow Bz > 0 Bz < 0

  4. Particle Picture of Magnetic Reconnection Ion flows Electron flows unit ViA unit VeA

  5. Hall Magnetic Fields

  6. Outflows Ve Ve Vi Vi Bz > 0Bz < 0 MHD Ion-electron decoupling MHD

  7. electron current layer - Vey Bz > 0Bz < 0

  8. The basic physical components on the magnetic reconnection site • The central electron current layer – the (electron) diffusion region • The ion-electron decoupling region – the Hall physics region • Inflows and Outflows – the MHD region

  9. 0700 UT

  10. electron Vx ion Vx ion Vy electron Vy

  11. electron Vx ion Vx ion Vy electron Vy electron Vperp x electron Vperp y 2 10 nA/m

  12. 0630 UT

  13. ion Vx ion Vy electron Vx electron Vy

  14. electron Vx electron Vy electron Vperp x electron Vperp y 2 20 nA/m

  15. 1055 UT

  16. electron Vx ion Vx ion Vy electron Vy

  17. Geotail Observations in the Plasma Sheet (plasma b > 1) in 1994-2010 X = -18 to -30 RE Y = -20 to +20 RE

  18. MHD flows Vi = Ve Errors are small when energetic electrons are rich. electron Vx ion Vx electron Vy ion Vy

  19. Tailward Flows with Bz < 0

  20. Tailward flows with Bz < 0

  21. Reconnection events

  22. Physical Size of the Magnetic Reconnection Site in the X direction in the Y direction ?

  23. 15 May 2003 near 1055 UT the spacecraft Geotail at 28 RE in situ observations of magnetic reconnection Geotail

  24. Bz < 0 Bz > 0 Earthward flows Bz > 0Bz < 0 Tailward flows Ion Et Earthward flows Tailward flows

  25. Main Targets of This Paper • Detect the central intense electron current layer • Get scales of magnetic reconnection • with Geotail observations • VA = 2,200 km/s • li = 1,200 km (ion inertial length) • Geotail MGF 16 vectors /s • LEP 12 s • electron g-factor 4x10 • DT 5.5x10 -4 -3

  26. Bz < 0 Bz > 0 Earthward flows 5 minutes Bz > 0Bz < 0 Tailward flows Ion Et Earthward flows Tailward flows

  27. Ion observations Bz > 0Bz < 0 Bz < 0 Bz > 0 Earthward flows 1000 km/s ion flow VA = 2200 km/s Tailward flows

  28. Ion flows vs. electron flows Ion Et Bz > 0Bz < 0 Bz < 0 Bz > 0 Vi Vx > 3000 km/s electron flows Vy > 6000 km/s electron flows Ve Ve

  29. Ion and electron flows perpendicular to the magnetic field Bz > 0Bz < 0 Bz < 0 Bz > 0 V Earthward flows Vx > 2000 km/s electron flows Vy > 3000 km/s electron flows Ve Tailward flows Ve

  30. Electron observations acceleration and heating electron Et Bz > 0Bz < 0 Bz < 0 Bz > 0 V Vx > 2000 km/s electron flows Vy > 3000 km/s electron flows Ve Ve

  31. Bz > 0Bz < 0 Earthward flows Tailward flows 1057:44 1053:44 UT time Earth tail Bz > 0Bz < 0 > 8.47 keV electron directional fluxes

  32. Bz > 0Bz < 0 Earthward flows Tailward flows 1057:44 1053:44 UT time Earth tail Bz > 0Bz < 0 electron velocity distribution function In the equatorial plane Vy < 0 dawnward Vy > 0 duskward

  33. Bz > 0Bz < 0 Earthward flows Tailward flows 1057:44 1053:44 UT time Earth tail Bz > 0Bz < 0 electron velocity distribution function Hall electrons

  34. Bz > 0Bz < 0 Earthward flows Tailward flows 1057:44 1053:44 UT time Earth tail Bz > 0Bz < 0 ion velocity distribution functions

  35. Bz > 0Bz < 0 Earthward flows Tailward flows time Bz > 0Bz < 0

  36. Bz > 0Bz < 0 Earthward flows Tailward flows time counter-streaming inflows Bz > 0Bz < 0 ion velocity distribution functions

  37. Important Questions ion-electron decoupling Ve >> Vi MHD MHD large Vey 1057:44 1053:44 UT intense electron current layer spatial scales?

  38. Asymmetric outflows MHD flows +450 km/s -650 km/s Earthward flow speed tailward flow speed

  39. MHD flows +550 km/s -550 km/s (+450 km/s) (-650 km/s) -100 km/s tailward velocity of reconnection site

  40. Bz > 0Bz < 0 Earthward flows Tailward flows time counter-streaming inflows Bz > 0Bz < 0 ion velocity distribution functions

  41. Asymmetric inflows inflows Vx = +64 km/s Vx= -269 km/s

  42. inflows Cluster results -100 km/s Baker et al. 2002 Imada et al. 2007 Vx = +164 km/s Vx= -169 km/s (+264 km/s -269 km/s) -100 km/s tailward velocity of reconnection site

  43. ion-electron decoupling region MHD MHD 1 li Earth tail central electron current layer 8 li Vx peak Flux peak Ion ele ele ion 8 li = 1.5 RE 1 li = 1200 km

  44. the X-line position PIC simulation results the northern earthward side of the reconnection site (upper-left quadrant)

  45. observation simulation at TΩi = 35 Vix / Vex 0.2-0.3 0.1 Vey / Vex 1.25 1.4 Vix 0.5 VA 0.3 VA the full extent of the central 1 li 1 li electron current layer the full extent of 8 li 8 li the ion-electron decoupling region

  46. 8 li = 1.5 RE ion-electron decoupling region Geotail Survey of Tailward Flows with Bz < 0 in 1995-2003 209 events Nagai et al., 2005

  47. Geotail Reconnection Events = Observations of Ion-Electron Decoupling Region 34 events 34/208 = 0.16 reconnection events at 20-30 RE Nagai et al., 1998; 2001