Escape of O⁺ through the distant tail plasma sheet

Abstract

In February 2007, the STEREO‐B spacecraft encountered the magnetosheath, plasma sheet and plasma sheet boundary layer from about 200 R E to 300 R E downtail. This time period was during solar minimum, and there was no storm activity during this month. Using data from the PLASTIC instrument, we find that even during quiet times, O + is a constant feature of the deep magnetotail, with an O + density of about 15% of the O + density in the near‐earth plasma sheet for similar conditions. The tailward flux of the O + is similar to the flux of O + beams that have been observed in the lobe/mantle region of the deep tail. The total outflow rate of the O + down the plasma sheet is 1.1 × 10 24 ions/s, which is 10% of the total outflow rate of 1 × 10 25 ions/s, and of the same order as the estimated loss from dayside transport.