ELECTRON DISTRIBUTIONS IN THE PLASMA SHEET BOUNDARY-LAYER - TIME-OF-FLIGHT EFFECTS

The electron edge of the plasma sheet boundary layer lies lobeward of the ion edge. Measurements obtained near the electron edge of the boundary layer reveal low‐speed cutoffs for earthward and tailward‐flowing electrons. These cutoffs progress to lower speeds with deeper penetration into the boundary layer, and are consistently for the earthward‐directed electrons than for the tailward‐directed electrons. The cutoffs and their variation with distance from the edge of the boundary layer can be consistently interpreted in terms of a time‐of‐flight effects on recently reconnected magnetic field lines. The observed cutoff speeds are used to estimate the downtail location of the reconnection site. Copyright 1990 by the American Geophysical Union.