Comparison of multi-point measurements of current sheet structure and analytical models

Abstract

Abstract. Current density profiles of 22 thin current sheets, crossed by four Cluster spacecraft in the magnetotail are compared with the self-consistent model of anisotropic 1-D equilibrium, including several species of quasi-adiabatic (transient) ions and drifting electrons. In order to examine ion-scale features of the current density profile Cluster data from the 2001 and 2004 tail seasons were used when the spacecraft separation was about 2000 and 1000 km, respectively, while electron-scale features are studied using Cluster data from the 2003 season , when the spacecraft separation was about 200 km. The model ion and electron current density peaks embedded in a background plasma sheet successfully reproduce observed profiles. Stability criteria of the model current sheet are also consistent with the experiment.

Thin embedded current sheets: Cluster observations of ion kinetic structure and analytical models

“…Using the CS model by Zelenyi et al (2004), which provides an essential embedding, Artemyev et al (2008a) have been able to reach an impressing agreement between theoretical and observed current density profiles. However, plasma density and temperature, required by the model to fit the experimental profiles were often rather different (by 30%) from the measured ones.…”

“…The ratio of proton and electron currents can be adjusted by parameter b n =B n B 0 . TACS embedding is controlled by the ratio of thermal and a flow velocities ε=v T v D at the edges of CS (Burkhart et al, 1992;Artemyev et al, 2008a).…”

“…The event set for our analysis was mostly adopted from several previous investigations. The fast crossings of 2001,2003,2004 were taken from Artemyev et al (2008a, their Table 1, ## 1-18, 20). Initially they were selected in earlier investigations by Runov et al (2006) and Nakamura et al (2006).…”

“…In this report we concentrate on the embedding of TCS (Asano et al, 2005;Runov et al, 2006;Artemyev et al, 2008a). The current density profile of an embedded sheet is substantially narrower, than that of the Harris sheet with the same maximum current density.…”

“…With the recent four-spacecraft observations in the Earth's magnetotail it is now possible to determine magnetic gradients, electric current densities, to restore (under the condition of stationarity) current density profiles across current sheets (CS) Nakamura et al, 2006) as well as to make quantitative comparisons with theory (Sitnov et al, 2006;Baumjohan et al, 2007;Artemyev et al, 2008a). Though some elements of CS structure were described in previous two-spacecraft, or even single-spacecraft experiments, these results substantially relied on lucky occasions and/or limiting suppositions about the sheet geometry Correspondence to: A. V. Artemyev (ante0226@gmail.com) and motion.…”