The role of upper hybrid waves in magnetic reconnection

W. M. Farrell, M. D. Desch, K. W. Ogilvie, K. Goetz, and M. L. Kaiser

NASA Goddard Space Flight Center, Greenbelt, Maryland 20771

Abstract:

Wind observations of upper hybrid (UH) waves adjacent to a magnetic X-line are compared with simultaneous Wind electron observations to clarify wave-electron interactions. Electron beams and "football" (T_|| > T_^) distributions accompany the UH waves. The energy density of the inward-directed beams at 10^-14 J/m³, is sufficient to supply the free energy for the waves. The electron beams may be part of the larger Hall current system, and the UH wave/electron instability represent a Hall current dissipation process (i.e., an effective resistance) which removes energy as the currents travel along the separatrix. It has been previously demonstrated that UH waves can stochastically accelerate non-resonant electrons to high energies (stochastic diffusion). We suggest that this mechanism may account for a Fermi impulsive perpendicular and parallel acceleration of electrons in the central X-line region.

in press, Geophys Res. Lett., 2003