FREJA OBSERVATIONS OF NARROW INVERTED-V ELECTRON-PRECIPITATION BY THE2-DIMENSIONAL ELECTRON SPECTROMETER

Observations of several steady, approximately 1-5 km scale inverted-V' s by the Freja F7 Two-dimensional Electron Spectrometer (TESP) are des cribed. Such narrow structures are not common, but provide an opportun ity for observing edge precipitation and the movement of arcs through the plasma. Velocities of inverted-V potential structures in the plasm a frame can be derived from the observed time delay between precipitat ing and mirrored electrons. These velocities determine whether horizon tal plasma flow into a potential structure can provide the source popu lation for arc edge precipitation. It is found that the intensity of t he arc edge precipitation is not associated in any expected way with t his velocity, indicating another source of plasma for arc edge precipi tation is required.