The self-consistent parallel electric field due to electrostatic ion-cyclotron turbulence in downward auroral-current regions of the Earth's magnetosphere. IV

Journal Article · Tue Jun 15 00:00:00 EDT 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3443713· OSTI ID:21378044

Jasperse, John R; Basu, Bamandas ^[1]; Lund, Eric J ^[2]; Grossbard, Neil ^[3]

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1. Air Force Research Laboratory, Space Vehicles Directorate, Hanscom AFB, Massachusetts 01731 (United States)
2. Space Science Center, University of New Hampshire, Durham, New Hampshire 03824 (United States)
3. Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts 02467 (United States)

The physical processes that determine the self-consistent electric field (E{sub ||}) parallel to the magnetic field have been an unresolved problem in magnetospheric physics for over 40 years. Recently, a new multimoment fluid theory was developed for inhomogeneous, nonuniformly magnetized plasma in the guiding-center and gyrotropic approximation that includes the effect of electrostatic, turbulent, wave-particle interactions (see Jasperse et al. [Phys. Plasmas 13, 072903 (2006); ibid.13, 112902 (2006)]). In the present paper and its companion paper [Jasperse et al., Phys. Plasmas 17, 062903 (2010)], which are intended as sequels to the earlier work, a fundamental model for downward, magnetic field-aligned (Birkeland) currents for quasisteady conditions is presented. The model includes the production of electrostatic ion-cyclotron turbulence in the long-range potential region by an electron, bump-on-tail-driven ion-cyclotron instability. Anomalous momentum transfer (anomalous resistivity) by itself is found to produce a very small contribution to E{sub ||}; however, the presence of electrostatic, ion-cyclotron turbulence has a very large effect on the altitude dependence of the entire quasisteady solution. Anomalous energy transfer (anomalous heating and cooling) modifies the density, drift, and temperature altitude profiles and hence the generalized parallel-pressure gradients and mirror forces in the electron and ion momentum-balance equations. As a result, |E{sub ||}| is enhanced by nearly a factor of 40 compared to its value when turbulence is absent. The space-averaged potential increase associated with the strong double layer at the bottom of the downward-current sheet is estimated using the FAST satellite data and the multimoment fluid theory.

• OSTI ID: 21378044
• Journal Information: Physics of Plasmas, Vol. 17, Issue 6; Other Information: DOI: 10.1063/1.3443713; (c) 2010 American Institute of Physics; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CYCLOTRON INSTABILITY
EARTH MAGNETOSPHERE
ELECTRIC FIELDS
ENERGY TRANSFER
INHOMOGENEOUS PLASMA
MAGNETOHYDRODYNAMICS
MOMENTUM TRANSFER
PARTICLE INTERACTIONS
PLASMA DENSITY
PLASMA SIMULATION
PRESSURE GRADIENTS
TURBULENCE
EARTH ATMOSPHERE
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
INTERACTIONS
MECHANICS
PLASMA
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
SIMULATION