Electric fields in the plasma sheet and plasma sheet boundary layer

Abstract

Data from the spherical double probe electric field experiment on ISEE 1 have been used to study a number of plasma sheet/lobe boundary crossings during intervals selected for the Coordinated Data Analysis Workshop 6 on March 22 and 31, 1979. These crossings took place during periods of substorm occurrence. They could be identified by keV plasma measurements and by using the electric field probes as a reference for measurements of the spacecraft potential. Typical spacecraft potentials in the plasma sheet are +10 V to +20 V. Because of decreased plasma density in the lobes the satellite potential increases here to +20 V to +30 V. Strong electric fields, with a dominant dawn‐to‐dusk component, are observed throughout the boundary layer outside the plasma sheet both for contracting and expanding motions of the plasma sheet and for different magnetic field directions. Characteristic amplitudes and durations are 5–10 mV m−1 and 5–15 min. The corresponding E × B vectors are always toward the plasma sheet. The spacecraft were situated both north and south of the plasma sheet edge, in such boundary layers, and in two or three cases the spacecraft were most likely on the earthward side of an X line. These latter cases coincided with the maximum of the expansion phase of substorms. Prior to these substorms, during plasma sheet thinning, onsets of sunward convection were observed by an electric field experiment on GEOS 2 in the geostationary orbit.

Evidence for kinetic Alfvén waves and parallel electron energization at 4–6 RE altitudes in the plasma sheet boundary layer

“…This factor was first predicted in the original proposal for the ISEE 1 spherical double‐probe electric field experiment (F. S. Mozer, personal communication, 2000). It was subsequently verified by extensive comparison in the solar wind of the electric field measured by the spherical double‐probe instrument to that derived from E =− v × B , where v is the measured plasma flow velocity and B is the measured magnetic field [ Pedersen et al , 1985]. No conclusions of W1 are modified by this change.…”

MHD turbulence in the Earth's plasma sheet: Dynamics, dissipation, and driving

“…For some time it has been noted that the flows of the plasma sheet are irregular [e.g., Hones and Schindler , 1979; Hayakawa et al , 1982; Sergeev and Lennartsson , 1988; Angelopoulos et al , 1993; Nakamura et al , 1994; BEFT1997; Yermolaev et al , 2000; Ovchinnikov et al , 2000; Neagu et al , 2002; Petrukovich and Yermolaev , 2002]. Consistent with the turbulent flow velocities, large fluctuations in the electric field are observed by satellites in the plasma sheet [ Cattell and Mozer , 1982; Cattell et al , 1986; Pedersen et al , 1985; BEFT1997, Figure 8]. The existence of turbulent magnetospheric flows has also been inferred from auroral images, auroral electric field measurements, and auroral particle measurements [ Kintner , 1976; Kelley and Kintner , 1978; Kintner and Seyler , 1985; Antonova et al , 1993].…”

Estimates of magnetotail reconnection rate based on IMAGE FUV and EISCAT measurements

“…According to Lockwood (1997) the open-closed boundary can be identified from the diffuse electron precipitation from the plasma sheet boundary layer or from the equatorward drifting arcs which form just equatorward of the open-closed boundary Hoffman et al, 1994) and are embedded in this diffuse precipitation. These arcs are also associated with intense electric fields (Pedersen et al, 1985) and thought to be Alfvén wave signatures of processes near or at the reconnection line (Hesse et al, 1999;Yamade et al, 2000). The accuracy by which one can determine the open-closed boundary is therefore highly dependent on the sensitivity and spatial resolution of the instruments that are used.…”