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IPELS, 29 June-3 July, 2003 Whitefish, Montana, USA

A. Vaivads, M. Andr é , S. Buchert, N. Cornilleau-Wehrlin, A. Eriksson, A. Fazakerley, Y. Khotyaintsev, B. Lavraud, C. Mouikis, T. Phan, B. N. Rogers, J.-E. Wahlund. IPELS, 29 June-3 July, 2003 Whitefish, Montana, USA. The small scale structure of the magnetopause Current layers and waves.

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IPELS, 29 June-3 July, 2003 Whitefish, Montana, USA

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  1. A. Vaivads, M. André, S. Buchert, N. Cornilleau-Wehrlin, A. Eriksson, A. Fazakerley, Y. Khotyaintsev, B. Lavraud, C. Mouikis, T. Phan, B. N. Rogers, J.-E. Wahlund IPELS, 29 June-3 July, 2003Whitefish, Montana, USA • The small scale structure of the magnetopause • Current layers and waves

  2. Why small scales and waves? • Importance for large scale phenomena • Decoupling of particles • Energy transport • Energy conversion, particle energization • Remote or local sensing tool • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  3. What we want to know? • Structure? sheet vs tube local vs global dispersion relation • Transport plasma, energy (particles, Poynting flux) • Momentum equationGeneralized Ohm’s law free energy • Energy conversion j·E • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  4. Cluster and magnetopause scales • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  5. Orbit in March Cluster orbit, magnetopause crossings after Parks(1991) • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  6. Magnetopause ~50 c/wpi Zoom into ~5 c/wpi • 2002-Feb-06 0810-0815UT • High latitude MP crossing • 100km Cluster separation • s/c in burst mode • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  7. Density dip ~1c/wpi • Narrow current sheet (yellow) 5-10le,re • Strongest E fields within the current sheet • Differences among s/c in E and B. • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  8. Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  9. Generalized Ohms law and Cluster • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  10. 5-10le,re current sheet,jperp and jII • B and n gradients coincides • E~j x B • pe not important • e- beam carrying jII can generate waves • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  11. E~j x B, all 4 s/c • Potential drop across the current sheet of a few 100 V • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary

  12. Numerical simulations of reconnection [Rogers] • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary • Two fluid, reconnection with a guide field • Te=0, t=0 • Width of separatrix is a few c/wpe • E is strong along the separatrix • E ~j x B, in most of the system

  13. MP reference frame • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary • EM>0, EN strong inside density dip • Inflow velocity ~ magnetopause velocity

  14. Waves strongest in the narrow current sheet (gradient in n and B) • Broad band • Spectral peaks f~fLH • Spectral peaks f~100 Hz, ’whistlers’ • Poynting flux associated to both ’whistlers’ and ’LHD’ • Waves generated by gradients or electron beams? n E • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary E B S  S

  15. Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary • 15-35 Hz band-pass filter (LH) • kre~1 • low coherence • wave transports e- across the current sheet. • D10-9 m2/s, Diffusion?

  16. Diffusion at magnetopause • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary Treumann [2001]

  17. Laboratory observations [Carter et al. 2002] MRX – magnetic reconnection experiment • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary • LHD waves • near the low-b edge • low coherence • no clear correlation with reconnection rate • Studies of B and narrow current sheets in progress

  18. LHD waves in laboratory vs. space • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary • Next step - to compare current sheets and whistlers

  19. Summary • Strong E (10s mV/m) within narrow current sheets ~10 c/wpeon magnetospheric side of MP • E~jxB, pe is not important • Separatrix of reconnection Other explanations? • Strong lower hybrid drift waves and whistlers • Electron transport due to LHD waves can be important only within the current sheet • D 109 m2/s, diffusion? • Comparisons with 3D numerical simulations • Many more events • Separatrix studies in lab • Intro • Cluster • MP crossing • E~jxB • Separatrix • Waves • Summary Future

  20. Particle diffusion, effective collision frequency Diffusion approximation Effective collision frequenacy • Analytically - n,v (E+dispersion relation) • Observations - n (satellite potential fluctuations) - v=ExB (for electrons)

  21. Other event 2001-03-02 E B S|| F

  22. Aurora vs Magnetopause • Aurora - ion scales, can go down to electron scales • Auroral field lines – narrow current sheets of Region I, II current systems strong jII, particle acceleration, waves often boundary phenomena (PSBL) • Infering EII from measurements of Eperp

  23. Scales Small spatial scales  between ion and electron scales and smaller  a few tens of km and below

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