Plasma sheet P^5/3 and n and associated plasma and energy transport for different convection strengths and AE levels

Abstract

[1] To understand the large-scale plasma sheet thermodynamics, we have used Geotail data and a formula for estimating flux tube volume V to investigate statistically the equatorial distributions of PV 5/3 and nV for slow flowing plasma in the nightside plasma sheet and compare them with the physical bases of ideal MHD and the Rice Convection Model (RCM). We have examined the distributions under three conditions: (1) weak convection and low AE, (2) enhanced convection and low AE, and (3) enhanced convection and high AE. The overall nV decreases significantly with increasing convection or AE, while the overall PV 5/3 remains similar. We found that PV 5/3 drops significantly earthward along the estimated electric drift paths near midnight, inconsistent with ideal MHD. Examination of P k V 5/3 and the electric and magnetic drift paths of different energy invariants, where P k is the partial pressure of a specific energy invariant, shows that the strong duskward drift of the above thermal-energy particles due to magnetic drift, together with there being significantly fewer higher-energy particles from the dawn flank than from the tail, results in the strong earthward decrease of PV 5/3 . We also found that d(P k V

Current sheet flapping in the near-Earth magnetotail: peculiarities of propagation and parallel currents

“…These positive strong gradients correspond to the quiet near-Earth magnetotail . The dominance of weak gradients ∂B z /∂x < 1 nT/ R E is attributed to observations at the flank magnetotail, where previous statistics show average values ∂B z /∂x ∼ 0.5 nT/ R E (Wang et al, 2009;Rong et al, 2014). However, the majority of observed CSs correspond to |∂B z /∂r l | < 0.2 with an average value of about ∼ 0.…”

“…In the near-Earth magnetotail we expect to observe relatively strong gradients of B z along the x axis (Kan and Baumjohann, 1990;Wang et al, 2009;Artemyev et al, 2013). The gradients ∂B z /∂x, ∂B z /∂y and ∂B z /∂r l , where r l = (r · l), of magnetic field in the current sheet centre is calculated for each crossing by means of the curlometer technique (Runov et al, 2005a) and presented in Fig.…”

Formation of the high-energy ion population in the earth's magnetotail: spacecraft observations and theoretical models

“…Thus, observed correlation between fluxes and B z (or v i ) can be explained by the heating of plasma (increase of T i ) due to dipolarization and enhanced convection. Indeed, many studies (e.g., Baumjohann et al, 1991;Wang et al, 2009;Kissinger et al, 2012) demonstrated that ion temperature T i grows as B z (or v i ) grows. Therefore, the formation of spectra of high-energy ions should be explained by some mechanism which does not involve a large-scale transformation of the magnetic-field configuration.…”

“…The upper limit of the ion acceleration in a quasistationary electric field is defined by the potential drop across the magnetotail ∼ 20-50 keV (Angelopoulos et al, 1993;Wang et al, 2009). Thus, to describe the formation of energetic ions with E > 50 keV, one should take a look at nonstationary mechanisms.…”

The Earth: Plasma Sources, Losses, and Transport Processes

“…Analysis of transport paths shows that E × B drift delivers particles toward the earth and the flanks, and thus cannot bring the flank source particles across the tail to midnight (Wang et al 2007(Wang et al , 2009. Magnetic drift can bring particles from the dawn flank into the midnight plasma sheet Wang 2004), however, magnetic drift is too small to move cold particles into the plasma sheet from the dawn flank.…”