Magnetic Reconnection Diffusion Region Research Articles

Evidence for electron acceleration up to approximately 300 keV in the magnetic reconnection diffusion region of earth's magnetotail.

We report direct measurements of high-energy particles in a rare crossing of the diffusion region in Earth's magnetotail by the Wind spacecraft. The fluxes of energetic electrons up to approximately 300 keV peak near the center of the diffusion region and decrease monotonically away from this region. The diffusion region electron flux spectrum obeys a power law with an index of -3.8 above approximately 2 keV, and the electron angular distribution displays strong field-aligned bidirectional anisotropy at energies below approximately 2 keV, becoming isotropic above approximately 6 keV. These observations indicate significant electron acceleration inside the diffusion region. Ions show no such energization.

Ion two‐stream and modified two‐stream instabilities in the magnetic neutral sheet

We study the stability of a magnetic neutral sheet that separates two regions of magnetized plasma. The particle species in the neutral sheet consists of: (a) trapped ions and electrons, which are confined within the current sheet, and (b) background ions and electrons, which partially penetrate into the current sheet. The diamagnetic currents of trapped particles and of background particles are in opposite directions, which produces an ion two‐stream distribution in the neutral sheet. It is found that, in addition to the lower hybrid drift instability, the ion two‐stream and modified two‐stream instabilities may occur in the neutral sheet with a thickness on the order of or smaller than the ion inertial length. These instabilities are also expected to occur in the dynamic diffusion region of magnetic reconnection.