General Disclaimer
One or more of the Following Statements may affect this Document
This document has been reproduced from the best copy furnished by the
organizational source. It is being released in the interest of making available as
much information as possible.
This document may contain data, which exceeds the sheet parameters. It was
furnished in this condition by the organizational source and is the best copy
available.
This document may contain tone-on-tone or color graphs, charts and/or pictures,
which have been reproduced in black and white.
This document is paginated as submitted by the original source.
Portions of this document are not fully legible due to the historical nature of some
of the material. However, it is the best reproduction available from the original
submission.
Produced by the NASA Center for Aerospace Information (CASI)
^^ I^`-
-
-
F
^
_ `` ~ { !^
V
-^
_
,.
.
^.
.^
^^^
X-621-69-51$
.
PREPRINT °
^^^^ rl^ .^- ^,3?
-:
OBSERVATIONS^OF IRREGULAR
= L -
-
^^
STRUCTURE IN '^IERM^L^ 101
DISTRIBI^-TI^JN'S IN THE DUSK-SIDE
MAGNETOSPHERE
I^,. -^
►
. TAY^oR
.,
W, C. BRINTOI+^
A. ^^ DESHMU[CH
I
^ECEMBER^1969
ems.
^ _
^^^
`^' `-^'^ 1"a,c'" -'^
^, ^_ . ^tui,^^y us ,
'^
I'
-
^
^3a
^^-
_
_^
t Y
^`'
y^^
-
^
0 Z,
--^-
GBDDA^D SPJ^CE F^.I^^^^
TER ._
-
_^
-
-^
6REENBE^T, ^ ^ARXLAt^-^
.
''', _ ,
- ;
-
N^0 -12 920
-
^
UCC[.[101
M[[Ill
s
-
0
^
OD[I
=
^
IIAY[[I
^^,
INA.A R A TMl[ 011 AD MUM• AI
lewr[oo11r1
^
r T
i
_
.,
.`.
:^^
^^.
X-621-69-519
t
%.
^:.
.}
^.
OBSERVATIONS OF IRREGULAR STRUCTURE IN
Tf-iERMAL ION DISTRIBUTIONS IN Tf->E
DUSK-SIDE MAGNETOSPI^RE
11. A. Taylor, fi. C. Brinton
Laboratory for Atmospheric and Biological Sciences
Goddard Space Flight Center
Greenbelt, Maryland 20771
and
A. R. Deshmukh
Aero Geo Astro Company
Belts^^ille, Maryland 20705
December19^9
OBSERVATIONS OF IRRECUI.AR STRUCTURE IN
THERMAL ION DISTRIBUTIONS IN TIC
DUSK-SIDE MAGNE"TOSPHERE
H. A. Taylor, H. C. Brinton
and
A. R. Deshmukh
ABSTRACT
Direct measurements of the distributions of the thermal positive
ions H
+
and He
+
in the magnetosphere reveal a distinct variability in
the position and structure of the plasr^^apause. Such variability is
observed to be most pronounced in the afternoon-dusk local time sector
,:
and is indicative of magnetospheric irregularities in the same region.
As the OGO-3 satellite made progressive dusk-side (1500 - 1900 L.T.)
and night-side (2200 - 0100 L.T.) passes during June-July 1966, the
dusk-side plasmasphere was observed to exhibit an outward expansion or
.
bulge, accompanied in some cases by considerable fine structure. In
particular, the plasmapause was observed at L positions as distant as
L = 7-8 in the afternoon-dusk sector, in contrast to positions near
L = 5-6 observed near midnight on the same day and at comparable
'
levels of moderate magnetic activity (Kp < 3). Within the bulge and
just above the initial plasmapause structured plasma recoveries are
observed, wherein n(H
+
) returns to concentrations of the order of
SO-100 ions/cm
3
over intervals of 0.5 - 1.5L. Both the dusk-side
i
,1
bulge and fine structure are observed to persist during periods of
enhanced magnetic activity (Kp = 4-6). The above variability is
superimposed on an average diurnal distribution of the plasmapause
which is similar in shape to that deduced from whistler data during
1963, although the 1966-67 results indicate that the plasmapause may
have expanded to a position generally more distant by about 1.5 - 2L.
The evidence of the plasma bulge and the associated plasma fluctua-
tions, is generally consistent with magnetospheric convection models
proposed by Nishida and by Brice. These models predict both a
similar local time asymmetry in the plasmapause radius, and a dusk-
side region of plasma turbulence, generated at the interface of
closed, co-rotating field lines and field lines which through con-
vection are connected to the n^agnetotail, and thereby provide a plasma
^
escape mechanism.
_^^
ii