Multi-point observations of the inner boundary of the plasma sheet during geomagnetic disturbances
Dandouras, I.; Glassmeier, K. -H.; Nakamura, R.; Carr, C.; Runov, A.; Larson, D.; Angelopoulos, V.; Ganushkina, N.; McFadden, J.
United States, Finland, Austria, France, Germany, United Kingdom
Abstract
We report on the THEMIS and Double Star TC-1 observations at the geocentric distances of 3 < R < 8 R E during substorms on March 23, 2007. THEMIS crossed the inner boundary of the equatorial dusk-side plasma in the string-of-pearls configuration, allowing the dynamics of particle populations to be traced within time ranges from hours to 10 minutes. Observations show co-existence of the plasma sheet ion population (5 - 30 keV) with the ring current ion population (100 - 1000 keV) at 4 < R < 6 R E . The plasma sheet population was characterized by pronounced ``nose''-like dispersion with the spectral density maximum at ~10 keV. The plasma sheet boundary, defined by a sharp decrease of the ~1 keV electron flux, moved inward to R = 4 and outward back to ~8 RE within about 1 hour. Local enhancements of the plasma sheet (1 - 5 keV) electron flux with the characteristic time scale of 2 - 10 min were detected at 5 < R < 6 R E during the substorm.