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 RE to 300 RE 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 × 1024 ions/s, which is 10% of the total outflow rate of 1 × 1025 ions/s, and of the same order as the estimated loss from dayside transport.