Journal article
Electron demagnetization and collisionless magnetic reconnection in β e ⪡ 1 plasmas
Physics of plasmas, Vol.12(9), pp.092903-092903-12
09/2005
DOI: 10.1063/1.2046887
Abstract
Abrupt, intense electric field enhancements (EFEs) with
E
>
100
mV
∕
m
surveyed over
3
years
of NASA's Polar spacecraft data are used to illustrate the occurrence and locales of nonguiding center demagnetization of thermal electrons in strongly inhomogeneous electric fields. A lower bound
E
*
(
a
)
on the perpendicular electric strength sufficient to cause nongyrotropic effects on the electron pressure tensor is determined for EFE thickness
Δ
x
=
a
ρ
e
. Minimum
E
*
(
a
)
occurs when
a
≈
1
. Of 258 observed EFEs, 15.3% (39) are demagnetizing (DEFEs) with
E
⩾
E
*
(
1
)
. DEFEs occur within
3
×
10
−
5
⩽
β
e
⩽
3
×
10
−
1
, while EFEs are found as low as
β
e
=
10
−
8
. While
E
*
(
1
)
does not depend on the ambient density, the DEFEs are organized by the density-dependent inequality
λ
De
∕
ρ
e
<
1
and are consistently understood as sites where the electron pressure tensor could become agyrotropic, enabling collisionless magnetic reconnection. The geophysical locales of the demagnetizing EFEs are not random, always occurring within magnetic cusp invariant latitudes, strongly concentrated at noon magnetic local times and at orbit apogee near the nominal magnetopause.
Details
- Title: Subtitle
- Electron demagnetization and collisionless magnetic reconnection in β e ⪡ 1 plasmas
- Creators
- J. D Scudder - University of IowaF. S Mozer - Space Science Laboratory, University of California at Berkeley, Berkeley, California 94720
- Resource Type
- Journal article
- Publication Details
- Physics of plasmas, Vol.12(9), pp.092903-092903-12
- DOI
- 10.1063/1.2046887
- ISSN
- 1070-664X
- eISSN
- 1089-7674
- Number of pages
- 12
- Language
- English
- Date published
- 09/2005
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199937402771
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