On the Transition Between the Inner and Outer Plasma Sheet in the Earth's Magnetotail

Abstract

We have statistically studied the average structure and properties of the plasma sheet in the Earth's magnetotail at radial distances between R ∼ 8 and 32 R E on the basis of ion, electron, and magnetic field data from the Geotail spacecraft. Here we discuss the transition between the inner plasma sheet and the outer plasma sheet near the equatorial plane. The ion and electron number densities, pressures, and energy fluxes at high energies, as well as the magnetic field, generally decrease with increasing radial distance from the Earth. The characteristics of the flux changes are reflected in the radial pressure gradients. If the transition between the inner and outer plasma sheet is determined by the radial pressure gradient change, the ion and electron transitions are located, on average, at R ∼ 11 to 13 R E and R ∼ 11 to 17 R E , respectively, at the midnight meridian. It is possible that the ion transition is located earthward of the electron transition. Furthermore, we have estimated the electric field, the electric and diamagnetic drift velocities, and the parameter (the square root of the ratio of the minimum curvature radius of the magnetic field line to the maximum gyroradius), which differ between the ion inner and outer plasma sheet.It can be seen from the results of previous studies that the properties of the plasma sheet differ between the inner and outer parts. Spence et al. (1989) obtained the X profile of the equatorial ion pressure for the midnight meridian. Wang et al. (2001), who numerically modeled the plasma sheet, also summarized previous observational results of the X profiles of the proton density, temperature, and pressure in the plasma sheet. Although these studies did not mention the inner and outer plasma sheet, their profiles showed

Space‐Ground Observations of Dynamics of Substorm Onset Beads

“…In the quasi‐steady plasma sheet, the duskward drift of plasma sheet ions is related to the diamagnetic drift (Wang et al., 2004), while the electron drift is related to the $$E\times B$$ drift by the equatorward (and earthward) electric field (Hesse et al., 1998; Lu et al., 2018; Zelenyi et al., 2010). The dawnward diamagnetic drift speed of electrons is much smaller (∼20%) than the duskward ion diamagnetic drift speed (Miyashita et al., 2020). While this event is overall consistent with their findings, a major difference is that the electric field was directed tailward (or poleward at off‐equatorial locations) and the $$E\times B$$ drift was duskward.…”

Ion Convection as a Function of Distance to the Neutral Sheet in Earth's Magnetotail

“…V E and V dia describe the motions of low and high energy ions respectively. We refer the readers to previous works (e.g., Hori et al., 2000; Miyashita et al., 2020; Wang et al., 2006) for a better visualization of the average vector profiles of V E and V dia .…”

Superthermal Proton and Electron Fluxes in the Plasma Sheet Transition Region and Their Dependence on Solar Wind Parameters

“…Intense magnetospheric electric fields during either large‐scale convection or localized plasma injections accompany transport of the energy and plasma from the plasma sheet into the inner magnetosphere (the radiation belt region), where the particles are further accelerated due to wave‐particle interactions (Thorne et al., 2013). Important changes of magnetic field and particle characteristics occur at the transition between plasma sheet and inner regions, roughly between 6 and 15 Re on the nightside (later referred to as the plasma sheet transition region, PSTR), their plasma physics is not yet fully understood (e.g., Baumjohann et al., 1989; Espinoza et al., 2018; Miyashita et al., 2020). Our understanding would benefit from models which quantify the changes in the PSTR and determine the factors which control these changes.…”