Author(s)
Gaw, Raymond C.
Title
Electron beams at geosynchronous orbit
Publisher
Monterey, California. Naval Postgraduate School
Issue Date
1993-09
URL
http://hdl.handle.net/10945/27022
This document was downloaded on May 04, 2015 at 22:46:11
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Electron
at
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Beams
Geosynchronous Orbit
by
Raymond C. Xlaw
Lieutenant, United /States
Navy
B.S.E., Central Missouri State University
Submitted
in partial fulfillment
of the requirements for the degree of
MASTER OF SCIENCE
IN
SYSTEMS TECHNOLOGY
from the
NAVAL POSTGRADUATE SCHOOL
September, 1993
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ELECTRON BEAMS AT GEOSYNCHRONOUS ORBIT
Gaw, Raymond C.
14 Date of Report (year, month, day)
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Master's Thesis
16 Supplementary Notation
in this thesis are those
The views expressed
15
Page Count
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September, 1993
of the author and do not reflect the official policy or position
of the Department of Defense or the U.S. Government.
17 Cosati
Terms (continue on reverse if necessary and identify by block number)
Plasmasphere, Plasmapause, Plasmasheet, Ion distribution, electron distribution,
Geosynchronous orbit, Maxwellian distribution, Magnetospheric Plasma Analyzer
18 Subject
Codes
Subgroup
Group
Field
19 Abstract (continue on reverse if necessary
and
identify by block
This thesis surveys electron and ion measurements
number)
collected by the geosynchronous satellite 1989-046.
In particular, this survey focuses
on
a
phenomenom
day
sudden acceleration of electrons along the earth's magnetic field lines. Observations over a twelve
of
Analysis
substorm.
magnetospheric
with
a
associated
injection
plasma
hot
period reveal electron beam occurrences during the first few minutes of
can be approximately fitted as Maxwellians, providing a means of
distribution functions show these beams have a characteristic peak. These distributions
Plots
of the differential flux also show a general diffusion of the beam
characterizing the temperature, density, and potential drop associated with the beam.
known
as "electron
beams", which are attributed
into neighboring pitch angles.
Theories on the source of the acceleration and diffusion are presented.
20 Distribution/Availability of Abstract
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Name of Responsible
R. C. Olsen
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Unclassified
ABSTRACT
This
thesis
collected
particular,
"electron
by
the
this
electron
surveys
focuses
which
beams",
are
ion
satellite
geosynchronous
survey
and
on
a
measurements
1989-046.
phenomenom known
attributed
to
the
In
as
sudden
acceleration of electrons along the earth's magnetic field
lines.
Observations over
a
twelve day period reveal electron
beam occurrences during the first few minutes of hot plasma
injection associated with a magnetospheric substorm.
of
distribution
functions
characteristic peak.
show
these
beams
Analysis
have
a
The distributions can be approximately
fitted as Maxwellians, providing a means of characterizing the
temperature, density, and potential drop associated with the
beam.
Plots of the differential flux also show a general
diffusion of the beam into neighboring pitch angles.
Theories
on the source of the acceleration and diffusion are presented.
in
TABLE OF CONTENTS
I.
II.
INTRODUCTION
1
BACKGROUND
4
A.
HISTORY
4
B.
THE NOMINAL GEOSYNCHRONOUS ENVIRONMENT
C.
THE DISTRIBUTION FUNCTION
7
D.
THE MAGNETOSPHERIC PLASMA ANALYZER
9
OBSERVATIONS
III.
IV.
V.
....
6
12
A.
FORMAT OF DATA PRESENTATION
12
B.
MAGNETIC ACTIVITY
15
C.
INACTIVE PERIODS
15
D.
ELECTRON BEAM DETECTION
16
CASE STUDIES
20
A.
APRIL 19, 1990
20
B.
APRIL 18, 1990
23
C.
APRIL 12, 1990
25
DISCUSSION
28
A.
ORIGIN OF BEAM PARTICLES
28
B.
METHOD OF ACCELERATION
29
IV
C.
VI.
DIFFUSION PROCESS
CONCLUSION
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APPENDIX-FIGURES
34
LIST OF REFERENCES
92
INITIAL DISTRIBUTION LIST
94
ACKNOWLEDGEMENT
The author wishes to express his gratitude to Professor R.C.
Olsen, whose physics knowledge and graphical expertise made this
research possible.
VI
INTRODUCTION
I.
It
of the universe
said that 99%
is
distinct
several
encounter
spacecraft
and
mission,
its
environments,
plasma
distinguished by energy and density.
a
the plasma
in
A spacecraft in orbit about the earth will likely
state.
of
is
each
Depending on the nature
it
may be
important
to
monitor the plasma environment in which the vehicle and its
These plasma environments have been the
pay load are immersed.
subject of intense study by space physicists over the past 40
years,
and
much
now
is
known
about
interaction with earth's magnetic field.
is by no means complete,
origin
their
and
This study, though,
and many important questions remain
unanswered.
Previous
plasma
environment
studies
have
reported
an
intense beam of electrons being accelerated along the local
magnetic
field
These
line.
electron
associated with plasma injection events
magnetospheric substorms)
acceleration method,
.
and
beams
are
often
(frequently called
The origin of these particles, the
the
diffusion
process
are
still
questions under debate.
An intense flux of electrons along the magnetic field line
was first reported by Hones et al (1971) using data collected
by the Vela satellites.
He termed these field aligned fluxes
'beams', but stated these fluxes did not contain a secondary
peak in their distribution function.
Electron beams,
with
local peaks in their distribution function, were subsequently
detected
Mcllwain
by
California,
San
using
(1975)
University
the
Diego auroral particles
of
experiment on the
Mcllwain showed these narrow field-aligned
satellite ATS-6.
pitch angle distributions found at geosynchronous orbit were
of recent ionospheric origin.
al
extended
(1979)
instrument
measuring
onboard
beams
these
ATS-6
in
Parks et al (1977) and Lin et
studies
did
not
have
directions,
both
ATS-6
of
the
and
capability
thus
could
distinguish whether the beams were bi-directional
directional.
The
data.
or
of
not
uni-
Further studies have reported the existence of
counterstreaming beams, which are beams propagating in both
directions along the field lines (Hada et al, 1981, Moore and
Arnoldy,
1982,
Klumpar et al,
however,
were
conducted
1988).
with
These latter studies,
instruments
which
could
not
resolve the energy distribution well enough to determine if
the distributions were beam-like in energy.
There remained a
need for measurements which provided full pitch angle and
energy distributions.
Whatever the method of creating and diffusing these beams,
it
is
undoubtedly
true
they are directly
involved
in
the
optical auroral
processes observed in the north and south
polar regions.
Eather el al
(1976)
has reported that the
auroral precipitation patterns in the polar regions share the
same
characteristic
shape
and
orientation
of
the
plasma
injection boundary.
the
presence
of
hot
Mende and Shelley (1976) determined that
plasma
(plasmasheet
electrons)
was
a
necessary but not sufficient condition for the occurrence of
conjugate auroras.
The data studied in this research paper was collected by
the
Magnetospheric
Plasma
Analyzer
National Laboratory instrument.
(MPA)
,
a
Los
Alamos
This instrument was mounted
on spacecraft 1989-04 6, which was subsequently launched into
geosynchronous orbit (6.6 earth radii).
from the MPA has an energy spectrum of
Particle count data
1
dimensions for both electrons and ions.
follow
further
describe
the
geosynchronous environment.
MPA
as
to
4
0000 eV in three
The sections that
well
as
the
nominal
BACKGROUND
II.
A.
HISTORY
Intense fluxes of electrons along the local magnetic field
line were first reported by Hones et al
(1971)
collected by the Vela
plasmasheet.
satellites
in
the
using data
He
suggested these electrons were associated with the auroral
phenomenon in the polar regions.
He showed these fluxes had
a narrow angular distribution centered along the field line,
and termed them 'beams', but he did not assert that they were
beam-like
in
which
energy,
a
peak
secondary
in
the
distribution function would reflect.
Mcllwain (1975) also reported intense fluxes of electrons
peaked at small pitch angles from data collected by ATS-6
(Figure
energy,
1)
.
He
plotted
the
distribution
function versus
and reported a secondary peak (Figure
2)
.
He named
this phenomenon an electron beam, and reported this beam was
travelling along the
northern
auroral
local magnetic
zone.
Mcllwain
field
line
concluded
toward the
these
beams
originated in either the ionosphere or the magnetosheath, and
were produced by either a potential drop or by heating of the
ionospheric ambient plasma.
Lin et al (1979) continued to analyze data from ATS-6, and
suggested the topside ionosphere as the likely source for the
This report also suggested beam particles are
electron beams.
scattered to large pitch angles by wave-particle interaction.
Further analysis of the ATS-6 data was conducted by Parks et
al
(1979)
who also reported a beam along the local magnetic
field line with a secondary distribution peak at approximately
This report concluded that both the ionosphere and
1.5 keV.
the plasmasheet populations are most likely involved as the
source
and
region,
variations
that
function only occurred during the
plasma injection event.
distribution
the
in
few minutes
first
of
a
Unfortunately, the detector aboard
ATS-6 was limited to looking in a single hemisphere, and thus
could
not
detect
if
were
beams
the
propagating
in
both
directions along the field line.
Hada et al (1981)
field-aligned
directional,
studied data from Imp
electron
distributions
and reported
6,
which
were
bi-
and possibly corresponded to beams reported by
Mcllwain (1975),
Parks et al
and Lin et al
(1977),
(1979).
These beams occurred in the plasmasheet and had an energy
range of several hundred eV to several keV.
To explain this
phenomenon, he suggested a Fermi-type acceleration where an
electric field is induced parallel to the magnetic field.
Klumpar et al
counterstreaming
(1988)
and Klumpar
electrons
AMPTE/CCE satellite.
from
data
(1989)
also reported
collected
by
the
These electrons were highly collimated
along the local magnetic field line, and were interpreted as
having
recently
emerged
from
the
auroral
ionosphere
as
secondary and backscattered primary electrons (Figure 3).
suggested
that
hot
plasmasheet
electrons
are
He
accelerated
downward into the source region by a parallel electric field.
This process creates a population of low energy secondary and
backscattered electrons which,
if
the potential barrier is
reduced in magnitude or moves to an adjoining flux tube, would
travel along the field line toward the conjugate atmosphere.
This intense flux would mirror in the opposite hemisphere, and
would be seen at the equatorial plane as highly field aligned
counterstreaming electrons.
Klumpar, however, did not report
that these counterstreaming beams had a
secondary peak in
their distribution function associated with a beam.
Further
study was needed to bring these ideas together.
B.
THE NOMINAL GEOSYNCHRONOUS ENVIRONMENT
A spacecraft in geosynchronous orbit will likely encounter
several
distinct
plasma
environments,
therefore
it
is
important to briefly describe these characteristic regions of
the terrestrial magnetosphere.
The earth's magnetic field
creates a semipermeable barrier to the solar wind produced by
the sun.
a
cavity
This barrier is called the magnetopause and creates
around
populations exist.
the
earth
in
which
various
particle
The magnetosphere, depicted in Figure
4,
is the region of space in which the geomagnetic field plays a
dominant role.
The position of the boundary, as well as the
position of the particle populations within the magnetosphere,
are highly variable, depending upon the level of activity of
As the activity increases, the boundary and particle
the sun.
populations move closer to the earth.
In this survey, the spacecraft encounters three different
regions:
plasma
plasmasheet.
dense
plasma
plasmasphere,
the
and
plasmapause,
the
The plasmasphere is a region of
low energy,
extending
ionosphere.
from
top
the
the
of
Particles measured in this region have typical energies < 20
eV and densities
of
approximately 10-100
cm"
3
.
The region
separating the plasmasphere from the plasmasheet is called the
plasmapause, and densities within this region will typically
drop to
1
cm"
the center
3
of
or less.
The distance of the plasmapause from
the earth varies according to the
magnetic activity.
level
of
McComas (1992) found that the plasmapause
moves across geosynchronous orbit in short periods of time, as
will be readily seen in this survey.
The plasmasheet is a region of high energy,
plasma.
Particle energy is on the order of
and densities are typically
1
cm"
3
.
.
1
less dense
keV to 10 keV,
The primary focus of this
research is on the inner boundary of the plasmasheet where
electron beams are frequently observed.
C.
THE DISTRIBUTION FUNCTION
The distribution function, or phase space density, is the
probability of measuring a particle at a position
velocity v, at time t.
It is expressed as
r,
with a
f=f(r,v,t)
One
common
type
of
distribution
function
is
called
a
Maxwellian, or Maxwell-Boltzmann distribution, where
~
f=n( '' t)(
The symbol
n(r,t)
is
OT
),e
tr
the number density,
and
given by
is
integrating over all possible velocities:
n(r,t)=jfff(r,v t)d v
2
l
The
symbol
electrons)
,
units of T,
eV,
mass
the
particle
this
case
m
is
the
k
is
the conversion factor appropriate for the
of
in this case Joules/eV,
(in
T is the temperature in
and E is the energy.
When a Maxwellian distribution function is plotted versus
energy on a semi-log scale, it forms a straight line in which
the slope is inversely proportional to the temperature,
the y-intercept is the particle density.
Figure
and
shows a
5
plot of the distribution function versus energy of particles
in the plasmasphere just prior to an injection in the dusk
region on
a
Maxwellian
The distribution function is
semi-log scale.
over
short
energy
ranges.
This
figure
shows
particles that are characterized by a temperature of 80 eV and
a
density of
4
geosynchronous
cm" 3
.
Lin et al (1979) has shown that plasma at
altitude
can
be
8
characterized
by
a
single
Maxwellian or a combination of two Maxwellians.
When electron
beams are present, the distribution function will contain a
secondary peak, or local maximum, as seen in Figure
peak
secondary
seen
the
in
Figure
is
nominally
The
6.
due
to
acceleration of the electrons along the magnetic field line by
a
parallel electric field.
The center of this peak indicates
the potential difference between the source region and the
Maxwellian approximations, seen as the solid line
detector.
in both Figures, will be least-squares fitted to the plotted
distribution function in chapter IV to analyze electron beam
observations.
D.
THE MAGNETOSPHERIC PLASMA ANALYZER
Presently,
designators
with
spacecraft
three
1989-046,
1990-095,
and
magnetospheric plasma analyzer (MPA)
.
the
1991-080
international
utilize
the
These spacecraft are
currently in geosynchronous orbit sending particle data to Los
Alamos
National
Laboratory
(Los
Alamos)
detailed
A
.
description of the MPA is presented by Bame et al (1993)
.
The
MPA was designed to measure three dimensional electron and ion
distributions in an energy range of
seen
in
Figure
electrostatic
7,
the
analyzer
MPA
(ESA)
is
1
composed
coupled
channel electron multipliers (CEM)
.
eV/q to 40 keV/q.
to
an
of
a
array
As
single
of
six
The ESA is composed of a
set of curved plates bent at a constant 60 degree angle, and
is independent of the polar angle of entry.
The particles are
then directed and post accelerated into the CEM array.
six
simultaneous measurements
provide
CEMs
polar angle field of view (FOV)
±11.
5°,
±34.
look directions centered at
8
relative response between CEM's.
channels,
through
the
ESA
illustrates the calibrated
The number three and four
the highest relative transmission
±11.5° have
at
different
and ±57.5° with respect to the spacecraft spin
5°,
The top plot of Figure
equator.
over
The
The
section.
bottom
plot
of
Figure
8
illustrates the expected FOV coverage for each CEM on a unit
sphere.
The spacecraft spin allows the MPA instrument to view
over 92% of the unit sphere, allowing for excellent coverage
of the surrounding plasma environment.
For this report, only
data collected by sensors three and four were surveyed as they
had
the
highest
probability
of
being
aligned
along
the
magnetic field line due to the alignment of the spacecraft's
spin axis.
The MPA produces five different types of data sets.
two
data
sets
utilized
this
in
report
are
dimensional observations of electrons and ions.
the
The
three
Each of these
data sets consist of 24 uniformly spaced exponential sweeps
from the top energy level to the bottom.
Each of these sweeps
collects counts in 40 nine-millisecond counting bins.
the
data
set
for
the
three
dimensional
Thus,
observation
of
electrons would contain six 24 by 40 matrices of particle
10
Each data set takes 10.15 seconds
counts, one for each CEM.
for a complete sweep of 365.5°.
Pitch angle information in previous plasma studies was
Satellite 1989-04 6 does
obtained by onboard magnetometers.
not have
an
The satellite
onboard magnetometer.
is
spin
stabilized with its spin axis pointed toward the center of the
earth.
Its
equatorial
orbit
plane.
defined as the
aperture
had
is
The
roll
angle of
passed
a
within
always
angle
rotation
northward
10°
of
latitude
this
of
spacecraft
the
is
completed since the MPA
facing
orientation.
The
earth's magnetic field lines are approximately perpendicular
to the equatorial plane at geosynchronous altitudes, and thus
parallel to the local horizontal.
At a roll angle of
0°,
the
MPA aperture is approximately viewing along the magnetic field
line in the northward direction.
In this survey,
angle of the spacecraft will be used as pitch angle.
angle of approximately
0°,
180°,
the roll
A pitch
and 360° will be measuring
electrons along the magnetic field line.
Equatorial trapped
electrons will be measured at approximately 90° and 270°.
11
OBSERVATIONS
III.
Eleven days of data collected by the MPA were observed as
electron spectrograms
beams.
for
the
purpose of viewing electron
Each day contained approximately 470 observations.
April 12 through April 21, 1990 were chosen due to a moderate
magnetic substorm observed during this period.
December 10,
1990 was chosen because the spacecraft did not encounter the
plasmasheet
during
the
magnetically quiet day.
hour
24
April
5,
indicating
period,
a
1993 was chosen to observe
more recent data collected by satellite 1990-095 during a day
of moderate magnetic activity.
Specific days and hours were
then chosen for a case study that will be presented in the
next chapter.
A.
FORMAT OF DATA PRESENTATION
Figures
9
and 10 show representative spectrograms of both
electron and ion fluxes on April 14,
collected by sensors
Chapter II.
3
and
the MPA
of
4
1990.
These data were
as
discussed
in
These spectrograms were created by integrating
counts collected by sensors
3
and
4
in the field aligned and
perpendicular directions respectively.
Particle flux levels
are denoted by a log 10 grey scale shown at the bottom of each
Figure.
The vertical scale represents the 40 energy channels,
12
measured in eV, through which the instrument swept during each
time interval.
The time scale is labeled in universal time
(UT)
To
.
convert to local time, add 13:00 hours to the universal time
for the April days and 13:20 hours for December
10.
Each
three dimensional measurement, or snapshot takes approximately
10
these measurement are not the
Unfortunately,
seconds.
and the time resolution
primary mission of this satellite,
The mean time between collections was
suffers considerably.
3
minutes for the full 3-D electron mode, with larger time
intervals when the satellite's primary mission preempted the
This time resolution had a detrimental
telemetry channel.
effect
this
on
survey
of
electron
beams,
which
will
be
explained in a subsequent chapter.
The low energy ions seen between 0100 and 0400 UT indicate
the spacecraft is within the plasmasphere.
A plasma injection
event is seen in the electron spectrogram at approximately
0440 UT.
This indicates the spacecraft is being enveloped by
A second plasma injection event of higher
the plasmasheet.
energy electrons is seen at approximately 063
this event were shown in Figures
5
and
6.
UT.
Data from
The faded vertical
strip at 1100 UT indicates the spacecraft is entering eclipse.
The low energy electrons seen between 0730 and 1600 UT are
those emitted by the spacecraft,
spacecraft
electrons
by
the
seen
in
potential
Figures
9
13
and then returned to the
barrier.
and
10
The
after
high
about
energy
0630
UT
indicate both field aligned and equatorially trapped electrons
throughout the rest of the day.
This research will focus on
electrons with an energy greater than about 50 eV.
Figure 11
is a plot of the full energy-angle matrix at the injection at
The detector number, the date, and time are listed
0640 UT.
at the top of the plot.
A differential energy flux versus
energy and pitch angle plot is in the lower left corner of the
This plot also shows the differential energy flux
Figure.
measured on a grey scale.
The log 10 grey scale is shown just
to the right of the plot, and
can be adjusted to highlight
the presence of electron beams.
As stated earlier,
aligned electrons will be seen at angles of
0°,
180°,
Equatorially trapped electrons will be seen at
90°
field
and 360°.
and 270°.
An electron beam is visible at a pitch angle of 180° and an
energy of
1
keV.
A characteristic sun pulse can be seen in
the lower right hand corner of the plot.
The
top
differential
left
hand
energy
corner
flux
perpendicular velocity.
the magnetic field line.
the
of
versus
Figure
parallel
is
a
plot of
velocity
and
The parallel velocity will be along
The grey scale representation of
flux is the same as that of the energy versus pitch angle plot
in the lower left hand corner.
A plot of the distribution
function versus energy and pitch angle is seen at the bottom
right hand corner of the Figure.
to the right of the plot.
The log 10 grey scale is shown
This scale can also be adjusted to
14
The top right hand corner
highlight features within the plot.
shows the same distribution function plotted versus parallel
and perpendicular velocity.
The grey scale representation of
the distribution function is the same as that in the lower
Data collected at specific pitch angles will
right hand plot.
be shown in a subsequent chapter.
B.
MAGNETIC ACTIVITY
Figure
12
illustrates
the
level
of
magnetic
during the period of April 12,1990 to April 21,1990.
activity
A storm
began on April 10, and slowly subsided over the next twelve
April 12 showed the highest level of magnetic activity
days.
for
the
data
observed
in
this
survey,
and
as
expected
displayed the highest frequency of electron beam occurrence.
December 10, 1990 was a magnetically quiet day, resulting in
the spacecraft remaining in the plasmasphere the entire day.
The magnetic activity for April
April
12,
1990,
and
displayed
5,
a
1993
was comparable to
similarly
high
level
of
electron beam occurrence.
C.
QUIET PERIODS
Electron beams were seen on most days, with the exceptions
in this study on April 16, April 21 and December 10.
April 16
and April 21 are days of low magnetic activity, resulting in
relatively mild injection events.
The field aligned data for
these days are shown as spectrograms in Figures 13 and 14
15
The conclusion that no beams occurred during
respectively.
hot
plasma
caveats.
injections
on
these
days
requires
some
strong
The minimum three minute time resolution between
detector sweeps may have played a substantial role in beam
There are many cases in this survey of electron
detection.
beam distributions fading in less than six minutes.
It is
quite possible that electron beams were formed at the plasma
injection events on 16 and 21 April, but were diffused before
the next
sweep by the MPA.
An
increased time resolution
between sweeps is required to solve this question.
As stated previously, December 10 was a quiet day, and the
plasmasheet remained outside the orbit of the spacecraft.
spectrogram for December 10 is shown in
Figure 15.
The
Electron
beams were not observed on this day, reinforcing the idea that
plasma injection from the plasmasheet is required for electron
beam development.
et al,
D.
1977)
Previous articles (Lin et al, 1979, Parks
have shown similar observations.
ELECTRON BEAM DETECTION
Data collected by sensors
3
and
4
of the MPA revealed at
least one electron beam event for each of the remaining days
in this survey.
in
A beam, again, is defined by a local maximum
the distribution
Every
function,
beam detected here
as
illustrated in Figure
occurred within minutes
after
6.
a
plasma injection, signifying a strong coupling between the two
events.
The intermittent samples prevented determining if
16
these two processes occur simultaneously.
A single beam was
Each of these
detected on April 13, April 19, and April 20.
beams diffused prior to the next detector sweep, indicating a
maximum lifetime of
6
Two beams were detected on
minutes.
April 14, each associated with a different plasma injection
(see Figure 9)
UT and the second was
The 0640 injection (Figure 11) produced the most
at 1000 UT.
energetic
The first was at 064
.
beam
this
in
Figure
survey.
distribution versus energy plot of the data,
secondary peak at 1900 eV.
shows
6
the
with a large
The accelerating potential was
estimated to be 1850 V, and was more than twice as large as
A Maxwellian fit of this
any other beam seen in this survey.
distribution gave a temperature of 576 eV and a density of .27
cm" 3
Each
.
beam
faded
before
the
indicating a maximum lifetime of
following
The
observations.
approximately
day,
The
0550,
April
first
in
detector
next
minutes.
6
15,
beam
was
1990,
detection
conjunction
with
similar
in
made
at
was
the
first
injection event of the day as illustrated in Figure 16.
beam diffused after approximately
9
minutes.
was detected at 0857, and diffused within
6
within
9
6
plasma
This
A second beam
minutes.
distinct beams were observed on April 17, 1990.
beams diffused within
sweep,
Three
Two of these
minutes, while the third beam diffused
minutes.
17
April
April 12,
5,
1993 was a magnetically active day,
similar to
Figure 17 shows the field aligned data in
1990.
energy versus time format for April
5,
1993.
The spacecraft
was within the plasmasheet until approximately 1000 UT (local
noon)
,
and experienced numerous plasma injections from the
plasmasheet.
The spacecraft then reentered the plasmasheet at
about 1600 UT (local dusk)
.
At least
7
electron beams were
recorded with energies ranging from about 100 eV to
a
maximum lifetime of about 20 minutes.
highest
energy
is
shown
in
Figure
potential was estimated to be 800 V.
1
keV and
The beam with the
The
18.
accelerating
A Maxwellian fit of this
distribution gave a temperature of 593 eV and a density of
1.54 cm" 3 at the source.
April
and
12
observations
of
18
were
electron
magnetically
beams
were
active
numerous.
days,
and
April
12,
April 18, and April 19 will be used for case studies in the
next chapter.
A total of approximately 30 electron beams were observed
in this survey, with an average lifetime of about 10 minutes.
The longest lifetime of a beam occurred on April 12 in which
the beam diffused after about 30 minutes.
These lifetimes are
only rough approximations due to the three minute time lag
between
detector
conservatively
sweeps,
high.
Mauk
but
and
are
considered
Mcllwain
(1975)
to
be
reported
electron beam lifetimes of hours, which may be explained by
18
the difference in magnetic activity between 1975 and 1990.
Work
by
Mauk
and
Mcllwain
relatively high magnetic
(1975)
activity
was
conducted during
period
compared
to
a
the
interval presented in this survey.
A second interesting difference between these surveys is
in
Mcllwain
beam energy.
(1975)
and
Parks
reported electron beam energies of a few keV.
the approximately
3
et
al
(1979)
By contrast, of
electron beams observed in this research,
only a few displayed an energy above
1
keV.
remaining beams ranged from about 40 eV to
Energies of the
1
keV.
These
observations are closer to those of Moore and Arnoldy (1982)
who reported counterstreaming. electron beams of a few hundred
eV.
The next chapter will present case studies of specific
beams found in this survey.
19
IV.
CASE STUDIES
Three days have been selected from the survey for a more
detailed analysis.
of
These three days were chosen for a range
quiet to active magnetospheric conditions.
program
was
developed
to
analyze
electron
A computer
distribution
functions in order to determine the temperature and density of
observed beams.
A.
APRIL 19, 1990
Figure 19 is a spectrogram for the field aligned particle
distributions observed on April 19.
A single plasma injection
The evolution of a
event is seen at approximately 1040 UT.
beam is illustrated by the sequence of Figures which follows.
Figure 20 and 21 show the energy versus pitch angle plots
collected by detectors
3
and
4
respectively at the injection
boundary when the beam is most distinct.
A high
flux of
pitch angle of 180° and an
electrons is seen in Figure 20 at
a
energy of approximately 600 eV.
Figure 21 also shows a high
flux of electrons at a pitch angle of
approximately 600 eV.
0°
and an energy of
These two 'beams' are counterstreaming
in nature; their appearance in adjacent detectors is a result
of the offset between magnetic field direction and the north-
south axis.
The velocity plots in both Figures also show a
20
high flux of electrons peaked along the
Vj
axis.
These are
the first indications that an electron beam may be present.
The distribution function plots in Figures 20 and 21 also
show an increased flux at 180° and
functions
distribution
respective
pitch
nominally
bi-directional.
detector
studies.
3
will
It
entire
survey,
primarily
at
fitted
the
with
the distribution functions are
nearly identical for detectors
the
energy
This is depicted in Figures 22 and
As these Figures show,
throughout
versus
least-squares
and
angles,
Maxwellian approximations.
23.
plotted
were
These
respectively.
0°
3
indicating
Therefore,
be
This was the case
and 4.
used
in
these
data
the
beams
are
collected
by
remaining
case
should be noted that data collected by both
detectors were surveyed for this project.
Figures 22 and 23 reveal the characteristic peak in the
distribution function indicating an acceleration of electrons
along the field line.
The temperatures in both Figures were
determined from the slope of the fit from 500-3000 eV.
This
fit assumes the distribution to be Maxwellian.
The density calculation has become inaccurate due to the
energy shift in the distribution function.
An accelerating
potential term must be added to determine the correct particle
density of the beam.
This correction is seen as:
21
n=n e
where n
kT
is the original density calculation as obtained from
a least squares fit to the distribution function.
is
The term
the accelerating potential of the electron beam.
q<p
This
correction will be included in a subset of the Figures which
follow to determine the density.
plot of the detector
3
Figure 24 shows a log-linear
data shown previously in Figure 22.
The density estimate has been corrected using the assumption
that the distribution is Maxwellian at its source.
The following four Figures show the distribution before
and after the beam measurement.
versus
energy plot on a
occurrence.
Figure 25 is the distribution
log-log
scale
just prior to beam
These data has been fitted with a Maxwellian
approximation to determine the temperature.
the data on a semi-log scale.
Figure 26 shows
Both plots are fitted from 100-
1000 eV, and show similar densities and temperatures prior to
beam development.
Six minutes after the beam is observed, it has diffused in
energy
and
pitch
angle.
Figures
27
and
28
distribution function in the same formats as above.
show
the
Figure 27
shows the distribution function and differential energy flux
versus energy about
6
minutes after the beam was detected.
Maxwellian fit is again used.
A
The characteristic peak in the
distribution function has practically disappeared, while the
22
temperature
over
the
same
500-3 000
log scale, and the density of 0.37
observed
in
energy
range
has
Figure 28 shows the same data on a semi-
increased to 860 eV.
that
eV
the
cm" 3
indicated
This
beam.
is nearly one quarter
diffused into the surrounding hot plasma.
beam had
the
This was the only
beam seen on April 19.
B.
APRIL 18, 1990
The second case study is from a more active day in the
The energy versus time spectrogram for
observation period.
April 18 is shown in Figure 29.
There are three distinct
plasma injection events at approximately 0400, 0840, and 1240
UT.
This case study will concentrate on events occurring
during the second plasma injection, when an approximately 100
eV beam is found.
Data are shown for 0843 to 0855 UT, which
is approximately 2200 local time.
Figure 30 is the energy versus pitch angle plots at 0843
UT
from
collected
data
by
detector
3.
A
high
flux
of
electrons is clearly seen at a pitch angle of 180° and an
energy of about 300 eV.
increased
direction.
flux
of
This
The velocity plot also shows an
electrons
is
being
believed
to
accelerated
be
the
in
beginning
the
v«
of
an
electron beam formation. Figure 31 is the distribution versus
energy plot at a pitch angle of 180°.
The characteristic peak
in the distribution function is not yet seen.
23
Figure
32
shows the data
in
energy versus pitch angle
format three minutes later at 0846 UT.
The flux of electrons
at 180° pitch angle appears to have increased in amplitude
with enhanced fluxes around 100 eV.
Figure
shows the
33
distribution versus energy on a log-log scale at
180°.
The
least-squares fit of a Maxwellian shows a small peak in the
distribution function at approximately 120 eV.
a
There is also
substantial depression in the distribution function at less
than 120 eV below what would be expected for a Maxwellian.
Figure 34 shows the same data on
a
semi-log scale.
The fit
from 300-900 eV show the temperature to be about 126 eV.
accelerating potential was estimated to be 100 V,
source density of 9.34
cm" 3
The
giving a
.
Figure 35 presents the energy-angle distributions for the
The flux at 180° appears to have the
next sweep at 0849 UT.
same characteristics as that seen at 0846 UT.
the field aligned data for this snapshot.
squares fitted with
eV.
a
Figure 36 shows
The data are least-
Maxwellian giving a temperature of 127
Figure 37 shows that once the accelerating potential of
approximately
100
describes the beam.
V
is
included,
a
density
of
7.47
cm" 3
This temperature and density nearly match
the temperature and density seen at 0846.
Figure 38 shows the third consecutive beam measurement at
0852
UT.
The beam flux at 180° pitch angle has decreased
substantially
from
that
seen
24
in
the
previous
two
sweeps,
.
indicating a diffusion of the beam.
distribution
energy
along
function
with
Figure
differential
and
Maxwellian
shows the
flux versus
energy
The
fits.
39
temperature
has
dropped to 81 eV, a decrease of about 50 eV from the previous
Figure
observations.
4
shows the estimated accelerating
potential of 80 V, giving a density of 2.02
cm' 3
.
Figure 41 shows data collected during the next sweep at
0855
UT
as
distribution
the
has
diffused in energy and pitch angle.
least-squares fit is 129 eV.
a
relaxed.
The
beam
has
The temperature from the
Figure 42 shows the same data on
semi-log scale, and displays the corrected density of 1.29
eV.
It appears from this series of Figures that the electron
beams observed at approximately 100 eV are from a distribution
function which is largely constant in temperature and simply
accelerated through varying potential drops.
C.
APRIL 12, 1990
April 12 was the most magnetically active day in this
survey,
and the
injection
spacecraft encountered a number of plasma
events.
Figure
spectrogram for April 12,
43
1990.
is
the
energy
versus
time
The first plasma injection
was at approximately 0330 UT, and plasma injections continued
until about 1215 UT.
This case study will focus on a plasma
injection at approximately 0520 UT,
1800 local time)
25
near local dusk
(about
Data are shown in detail for an
3
minute interval in four
Figure 44 shows the first segment,
snapshots.
detector
8
The plot shows a concentration of flux
at 0521 UT.
at pitch angles of
and 180° and at energies of about 50 eV.
0°
The velocity plot shows a high flux along
and negative values.
both
directions
collected by
at both positive
Vi
This clearly shows an acceleration in
along
the
magnetic
field
This
line.
counterstreaming is seen throughout the injection events on
April 12.
Figures
and
45
show the
46
field
aligned data.
The
distribution has been least-squares fitted with a Maxwellian
distribution, giving a temperature of 54 eV.
A small hump
appears to be forming at an energy of about 20 eV.
shows
the
data
on
semi-log
a
The
scale.
potential was estimated to be 40 V giving
cm" 3
a
Figure 46
accelerating
density of 13.5
It is believed this is the start of a beam development
.
for this injection event.
Figure
47
shows
the
sweep
next
at
0524
concentration of flux is again seen at pitch angles of
180°.
Counterstreaming
continues
to
be
A
UT.
0°
observed.
and
The
dimensions of the flux appear to be the same as that seen at
Figures 48 and 49 show the field aligned data in
0521 UT.
line plot form.
a
Maxwellian,
formed
in
the
The data have been least-squares fitted with
giving
a
temperature of
distribution
at
26
an
34
energy
eV.
of
A peak has
about
50
eV.
Figure 49 shows the data in semi-log form.
An accelerating
potential of 50 V was estimated, giving a source density of 29
cm'
The distribution function again shows a substantial
3
.
depression
energies
in
than
less
the
local
This
peak.
depression suggests the possibility that electron beams are
due
to
the
dropout
of
low
energy
electrons
vice
the
development of a secondary peak in the distribution function.
Figures 50 through 52 show data from the next sweep by the
MPA at 0526 UT.
The shape of the pitch angle distribution
appears to be the same as that seen in the previous sweep.
The velocity plot still shows counterstreaming electrons along
the magnetic field line.
50 eV.
The line plot gives a temperature of
The corrected source density is shown to be 17.65
cm"
3
.
The conclusion of the sequence is shown in Figures 53-55
at 0529 UT.
The data are not substantially different from
those taken in the previous three sweeps by the MPA.
Figure
54 is the distribution versus energy plot on a log-log scale,
and again shows the peak characterizing an electron beam.
Maxwellian fit gives a temperature of 52 eV.
the same data on a semi-log scale.
The
Figure 55 shows
The accelerating potential
was estimated to be 80 V, giving a density of 28
cm"
3
.
The
next sweep of the MPA was made at 0532 UT, and showed the beam
had
diffused
in
pitch
angle
and
energy.
This
diffusion
translates to a beam lifetime of approximately 11 minutes.
27
DISCUSSION
V.
There are three primary questions that remain unanswered
with respect to electron beams.
This
These questions are:
1.
What is the origin of the particles in the beam?
2.
What is the acceleration method?
3.
How and where is the electron beam diffused?
chapter
will
theories
compare
presented
in
previous
research to the observations made in this thesis.
A.
ORIGIN OF BEAM PARTICLES
Many previous research papers attempted to explain the
origin of particles in electron beams.
Parks et al
(1977)
deduced the increased electron flux seen along the magnetic
field line originated in the upper atmosphere
Lin et al
(1979)
(ionosphere).
reported that the beams were confined to
pitch angles of approximately 10-30° at the equatorial plane,
and suggested that the ionosphere was the likely source of the
particles.
Parks et al
are characteristic of
(1979)
reported that electron beams
ionospheric potentials,
but that the
particles are probably of two sources; the ionosphere and the
plasmasheet.
Mcllwain
(1975)
also
argued
that
the
distribution functions of these beams indicate that at least
some of the particles in the beam originate in the ionosphere.
A recent article by Klumpar (1989) concluded that the enhanced
28
electron fluxes (beams) encountered along the magnetic field
line
secondary
are
backscattered
and
electrons
from
the
auroral ionosphere.
Observations
ionosphere
the
as
this
thesis
also
likely
source
for
in
support
electron
topside
the
The
beams.
enhanced fluxes are counterstreaming as in Klumpar (1989) and
temperature,
exhibit
and
flux,
particles in the topside ionosphere.
particles
through
stable
relatively
constitute
that
environment,
their
the
The beams appear to be
lifetime,
suggesting
beam originate
such as the ionosphere.
with
consistent
density
in
a
the
stable
The beams are highly
field aligned, intimating that the origin of the particles is
not local, but at some distance along the magnetic field line.
METHOD OF ACCELERATION
B.
Electron
beams
the
are
result
of
accelerated along the magnetic field line.
in
thesis
this
ionosphere.
suggest
It
is
these
also
clear
particles
from this
particles
being
The observations
originate
in
the
observation that
electron beams are formed at or just after a plasma injection
event upon passage of the plasmasheet in the equatorial plane.
This
suggests
that
acceleration
the
method
must
form
a
connection between these two events.
A common
potential
region.
idea
structure
in
is
all
acceleration theories
is
that a
formed just above the acceleration
Tetreault (1991) suggested that double layers formed
29
.
by hole/clump instability along the magnetic field line can
cause a sufficiently large potential drop to form electron
beams.
The existence of these double layers has been shown,
but it is still uncertain whether these interspersed double
layers can accumulate the potential necessary to form electron
beams
A second acceleration theory involves parallel electric
fields.
Lin et al (1982) suggested the acceleration method is
oppositely directed electric fields pointing to the spacecraft
along
the
magnetic
Mizera
field.
(1977)
showed
that
substantial electric fields along the magnetic field line are
operating over both hemispheres at an altitude of less than
These electric fields produce accelerating
two earth radii.
potentials along the magnetic field line at low altitude.
Klumpar
(1989)
has suggested that plasmasheet electrons
are accelerated downward by a parallel electric field.
energetic
electrons
secondary
produce
electrons in the ionosphere.
and
These
backscattered
A diminishing or movement of the
potential structure above the ionosphere would allow these
electrons to escape along the magnetic field line, forming the
beams
seen
at
the
eguatorial
plane.
Figure
56
is
an
illustration of this theory, and is considered by the author
to be the most viable theory in the formation of electron
beams.
30
DIFFUSION PROCESS
C.
Observations in this research indicate the lifetimes of
This dictates
electron beams are on the order of minutes.
that a strong diffusion process must take place along the
field
line
to
dissipate
the
although
beam,
part
of
the
evolution may be due to the relative motion of the spacecraft
Figure 57 is the energy versus pitch
to the injection front.
angle plot from data collected by detector three on April 17,
1990.
An electron beam is seen at a pitch angle of about 180°
and at an energy of
2
00
Just above the beam are two
eV.
concentrations of flux bending toward equatorially trapped
Figure 58 also shows a concentration of flux
pitch angles.
bending away from the beam and towards pitch angles of 90° and
270°.
Two
contrasting
The
Figures.
equatorially
conclusions
first
trapped
can
possibility
pitch
angles
be
is
are
drawn
from
these
electrons
that
losing
forming an electron beam along the field line.
energy
at
and
Observations
shown here indicate that the beam densities require that the
beam originate in the ionosphere, not the equatorially trapped
particle population.
within
the
beam
The second possibility is that particles
are
gaining
neighboring pitch angles.
energy
and
diffusing
into
A widely cited diffusion process by
whistler mode waves, as discussed in Johnstone (1993)
,
the mechanism necessary to support this possibility.
31
provide
Electron
beams
Magnetosphere.
VI.
CONCLUSION
are
a
common
Observations of
disclosed the presence of over
occurrence
spectrograms
in
the
11
days
from
distinct electron beams.
3
These beams appear at or just after a plasma injection from
the plasmasheet.
The beams are travelling in both directions
along the magnetic field line,
indicating counterstreaming.
An interesting observation is that beam temperature is not
dependent on substorm intensity.
April 12, 1990 displayed the
highest magnetic activity,
but the beam temperature was no
higher than in other days.
Beam lifetime, though, did appear
to depend on substorm intensity as beams detected on April 12
lasted up to five times as long as beams detected on other
days.
temperature
Beam
Maxwellian
and
approximations.
density
The
were
using
determined
estimated temperature
and
density remained nearly constant through the beam's lifetime,
and
are
consistent
ionosphere.
with
particles
found
in
topside
the
The topside ionosphere is the suggested choice
for the origin of the particles in the beam.
Klumpar's (1989) electric field model is consistent with
the observations in this research, and is marked as a viable
solution to the acceleration question.
conclusions
are
also
supported
32
by
Hada et al's
observations
in
(1981)
this
.
Lack of a wave sensor on the spacecraft prevented
research.
determining if a wave-particle interaction caused dispersion
Observations in this report suggest particles
of the beam.
within the beam gain energy and are diffused into neighboring
pitch angles.
Whistler mode waves are suggested as the cause
of this diffusion.
The three minute time lag between sweeps was detrimental
The number of beams and their
in the analysis of this data.
respective
lifetimes
can
only
be
estimated,
as
their
development and diffusion could have occurred between sweeps.
Improvements in the time resolution would prove helpful in
While it is essential in
answering some of these questions.
plasma physics to collect data at all pitch angles, it would
prove
also
magnetic
useful
field
train
to
line
to
a
plasma
continuously
detector
collect
along
data.
the
Beam
development and diffusion would be accurately recorded by such
a detector.
The observations made in this report cover a relatively
short period, and conclusions drawn are subject to change by
a
more
extensive
survey.
It
is
recommended
collected by the MPA on satellites 1989-046,
that
1990-095,
data
and
1991-080 be furthered studied to accurately analyze electron
beams
33
1
1
APPENDIX
—
Mlj
1
"I
I
'
I
1
I
1
I
|
I
III
4
6
1
I
PITCH ANGLES FOR
8
10
—
1
|
I
I
II
I
1
1
*'S
2
I
."*
,*x
10-
""""""""".••••--•-
XXX"
•••
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I
PITCH ANGLES FOR «'S 70* TO 90*
\
-
•
*
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_i
I0<
• x
0555 27-40 UT
JUNE 16, 1974
DAY 167
10*
i
i
I
i
i
_i
i
i
X
•I
i
i
i
1
10"
1
I
10*
E--ENERGY
IN
I0
3
EV
Figure 1 The differential number flux of electrons travelling
close to the magnetic field direction measured during the first
minutes of a magneto spheric substorm plasma injection.
Figure
1
Electron Flux versus Energy, Mcllwain (1975)
34
r
1
IVI
<
VELOCITY
10"
IN
3x10*
i
'
1
KM/SEC
—
100
PITCH ANGLES FOR
8
10
10
'.
X.X
*"*«*,
I
xxx
••
•
—
4
6
*'S
2
12
xx x
..«
'•••,
"•
x
PITCH ANGLES FOR *'S 70* TO 90'
to
*.'
•
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«
•
»
•
?
0555 27-40 UT
JUNE 16, 1974
.01
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x
•
«
•
167
x
•
x
•
.001
i
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.0001
i
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i
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i
1
I0<
E
Figure
scales.
i
^
=
ENERGY
IN
EV
The distribution function replotted using logarithmic
Distribution versus Energy, Mcllwain (1975)
35
10
T
-r
T
<_
l
2.9-4.9
'
l
keV
85152
a
23:18:53-23:18:59
-—
6.6-11.1
15.-25.
210
PITCH ANGLE
Figure
3.
keV
keV
270
(°)
Pitch angle distribution showing the three
components
of the distribution: loss cone component, halo component, and
locally trapped
Figure
3
component
Electron Flux versus Pitch Angle, Klumpar (1989)
36
FIGURES
APPENDIX B
Magnetosphere
Figure 5.4
Cross section of the magnetosphere showing the prin-
cipal current systems:
magnetopause current,
cross-tail (or neutral)
current sheet, ring current, and field aligned currents. Also
are the regions of convective and co-rotation
Figure
4
shown
plasma flow directions
Cross Section of the Earth's Magnetosphere
Tascione (1988)
37
4
i
-APR- 90
6:34:23
n
n (V)
<
-
kT -
o
79.80 eV
Detector 3
it:
<\nqle
3
cm
»
c
$
3.8
=
180
lo'
1"
10
L
400
600
800
__J
1
000
Energy (eV)
Figure
5
Representation of Distribution Function
38
141
APR-90
6:40: 8
=
cm" 3
fj()()(l
n(V)
1
(II
0.7/
A'-'-elernting Potentiol
V)
kl
1850.0 V
-
=576.41 pV
Detector 3
100
Angle
-
180
n
in
.>*.
1000
2000
3000
4000
5000
Energy (eV)
Figure
6
Representation of Distribution Function with
Electron Beam
39
AHOU WAWOt
AZIMUTH
iO«t «HO fltCTMON*
tf*J
»*«
POIAH ACCfrTAHCf
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Figure
7
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»«U
a
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other feature* of the
or
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Cross Sectional Views of the MPA
Bame (1993)
40
into the
pp
«olar
of the platev sot tbovn in the
-J»
FIG
J
CileuUiad.
MP*
FIG
sphere
Figure
8
-*0 -40
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POLAR ANOUE
pfOClEV l^p
MPA transmmkxt
40%. ind 10*
ihown on
Contouri of
8
tt
the \0%,
the unit
Irrtfc.
MPA Transmission Response Curves and Unit Sphere,
Bame (1993)
41
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
1989-046
14-APR-1990
Field-Aligned
35415.2
>
en
i-
0)
c
UJ
c
o
1-
o
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38219.3
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5991.8
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c
c
o
12
TIME(HR)
20
16
Log 10 Flux
Electrons
1.0
'
Ions
Plot run
0.0
28-May-1993 11:02:36.00
Figure
9
2.0
1.5
":
'
$:
3.0
:
0.5
1.0
1.5
Naval Postgraduate School
Energy vs Time Spectrogram
42
2.5
i»l
— Field
Aligned
24
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
1
989-046
1
4-APR- 990
1
Perpendicular
>
a>
a>
c
lj
c
o
l_
o
>
en
38219.3
17274.3
5991.8
2078.3
-§
720.9 t
k_
a>
c
UJ
c
o
8
12
TIME(HR)
16
20
Log 10 Flux
Electrons
1.0
Ions
28-May-1993 11:04:15.00
Naval Postgraduate School
Figure 10 Energy VS Time Spectrogram Perpendicular
Plot run
—
A3
24
LANL MPA - 1989-046
Detector 3
14-APR-90
6:40:08
- 3270.09 eV
1
•30
3270.09 eV
30
-30
30
V x (Mm/s)
V x (Mm/s)
Log
Diffl
Energy Flux
Loq
Dist.
Fen
7.5
10000
2.0
7.0
1.5
6.5
1.0
6.0
0.5
90
180
270
360
5.5
Figure
11
90
180
270
Pitch Angle
Pitch Angle
Energy versus Pitch Angle Spectrogram
44
360
0.0
p
Magnetic Activity
4
r\r\
i
——— ————— — —— ——
f
i
»
i
i
»
i
»
f
»
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»
1
1
1
1
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l_l
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-200
-300
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1
20
15
April
Figure 12
I
25
I
1
I
l_
30
1990
Magnetic Activity, April 12 through April 21,1990
45
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
1989-046
16-APR-1990
Field— Aligned
>
i-
CD
C
Ld
C
o
u
_cd
LJ
>
<v
l
C
UJ
c
o
12
8
20
16
TIME(HR)
Log 10 Flux
Electrons
Ions
Plot run
0.5
0.0
27-Jul-1993 17:31:37.00
Figure 13
1.0
1.5
0.5
2.0
2.5
1.0
1.5
Naval Postgraduate School
Field Aligned Spectrogram for April 16, 1990
46
24
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
21-APR-1990
1989-046
Field— Aligned
>
>»
i_
c
bJ
C
o
o
>
L.
0)
c
20
16
12
TIME(HR)
8
Log 10 Flux
Electrons
lons
Plot run
0.0
0.2
29-May-1993 14:45:40.00
Figure 14
0.4
0.6
0.8
1.0
1.2
1.4
Naval Postgraduate School
Field Aligned Spectrogram for April 21, 1990
47
24
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
1989-046
10-DEC-1989
35415.2"
16006.8^
>
5552.1
^<
1925.8
fc
668.0
c
24
20
16
12
8
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TIME(HR)
i
i
1
16
i
i
i
1
i
20
i
i
24
Log Flux
Electrons
0.6
Ions
0.0
Plot run
27-May-1993 18:25:52.00
Figure 15
Naval Postgraduate School
Energy versus Time Spectrogram, December 10, 1990
48
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
1989-046
5-APR-1990
Field-Aligned
>
cn
^_
a>
c
c
o
L.
o
LJ
>
CD
cn
l.
a>
c
LJ
C
o
12
16
20
TIME(HR)
Log 10 Flux
Electrons
0.5
1.0
1.5
Ions
Plot run
1
6-Jul- 993 15:36:22.00
Figure 16
1
Noval Postgraduate School
Energy versus Time Spectrogram, April 15, 1990
49
24
Los Alamos National Laboratory Mcgnetospheric Plasma Analyzer
05-APR-1993
1990-095
Field— Aligned
>
cx>
a>
c
LxJ
C
o
o
>
>s
CT>
i_
CD
c
c
o
20
12
8
TIME(HR)
Log 10 Flux
Electrons
Ions
Plot run
0.5
0.0
27-Aug-1993 14:17:47.00
Figure 17
1.0
1.5
0.5
2.0
2.5
1.0
1.5
Naval Postgraduate School
Energy versus Time Spectrogram, April 5, 1990
50
24
05- -APR-93
ono
'
'''
•
1
1:44:41
•
=
n(V)
•
*
>
c
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100
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•
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•
>
*
>
'
cm" 3
1.54
Accelerating Potential
o
o
1
i
=
-
800.0 V
=593.46 eV
kT
•
-
N
Detector 3
c
Angle =
.
C
180
o
~3
1
1.
X)
.
1
,
.
1
•
•
1
•
1
1
1
2000
1000
1
1
1
1
r\
1
1
1
1
»
4000
3000
Energy (eV)
Figure 18
Distribution versus Energy, April
51
5,
1993
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
19-APR-1990
1989-046
Field— Aligned
>
cn
^_
C
C
O
a
a;
LxJ
>
tu
c
Ld
c
O
12
16
20
TIME(HR)
Ions
Plot run
0.0
19-Aug-1993 10:36:41.00
Figure 19
0.5
1.0
1.5
Naval Postgraduate School
Energy versus Time Spectrogram for April 19, 1990
52
24
1
LANL MPA - 1989-046
Detector 3
19-APR-90
10:43:30
- 3270.09 eV
1
- 3270.09 eV
1
30*«<*3Sgp*f
20-
'
jjfc-
10
mm-
Hi
#
mm§A
1
i
Ipv
20
i
30
i
-30
Loq
lZj
Diffl
u_j
i
-30
30
o
Vj.
30
(Mm/s)
V x (Mm/s)
Enerqy Flux
l_i
2A
Loq
-'
i
i
i
Dist.
Fen
i
i
I
2.0
10000
7.5
1.5
en
7.0
en
1.0
6.5
0.5
90
180
270
360
6.0
Pitch Angle
Figure 20
90
180
270
360
Pitch Angle
Energy versus Pitch Angle
53
— Detector 3 — April
19
0.0 _
LANL MPA - 1989-046
Detector 4
19-APR-90
10:43:30
3270.09 eV
- 3270.09 eV
1
-101
30
30
-30
Log
Diffl
Energy Flux
10000
100
Loq
Dist.
Fen
90
180
270
7.5
1000
uj
30
o
V x (Mm/s)
V x (Mm/s)
7.0
-
6.5
6.0
90
180
270
360
5.5 L_
Figure 21
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle
54
— Detector 4 — April
19
19-APR-90
8
10°
'
'
=
n
.
'
3.41
10:43:30 UT
;
""'
8
cm
10
6
""'
Angle =
•
kT =
""'
522.54 eV
180
••
•
•
•
/
d 3
:•
•
>
/
•
LJ
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4
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7
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2
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10°
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r2
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1
A.
5
-
-
—
I
/
1
.
."..1
1
100
1000
Energy (eV)
100 1000 10000
Energy (eV)
Figure 22
•
/
•
\
10
/
\*
Distribution versus Energy
55
j
i
i
in
10000
— Detector — April
3
19
19-APR-90
10
(
"""1
'
—
n
10:43:30 UT
T
'
'
1.83
cm
-3
kT = 643.28 eV
•
10
•
-
•
•
•
•
•
10
-
•
•.
10
•
z
»••
~*^*
V
10
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•
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10
•
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-2
.
1
Figure 23
1
IMHilL
1
L
1
,,„|
|
,,,!,„
100 1000 10000
Energy (eV)
10
100
1000
Energy (eV)
10000
Distribution versus Energy—Detector 4--April 19
56
.
19- -APR-90
1000
.
1
i
,
,
10:43:30
,
,
,
E
k
n(V)
=
1.31
Acceleroting Potential =
c
100
o
u
s«
C
kT
•
•
c
D
o
,
E
cm -3
-
500.0 V
=522.54 eV
|
•
•
-
Detector 3
•\.
Angle =
180
-
10
1
-
.
.
.
,
,
,
.
,
1
1
J
1000
1
.
1
1
2000
3000
4000
5000
Energy (eV)
Figure 24
—
Distribution versus Energy Detector
Corrected Density Calculation
57
3
— April
19
19-APR-90
10
n,
C
n
10:40:38 UT
|
=
0.50
kT =
cm -3
174.84 eV
10'
10
10'
10
v
-2
100 .1000 10000
Energy (eV)
10
Figure 25
1
Distribution versus Energy
58
10
1000
100
10000
Energy (eV)
— April
19
— 10:40:38
UT
'
19-APR-90
1000
,
,
t
.
.
.
10:40:38
.
.
,
.
,
.
,
n(V)
=
0.50
4
cm" 3
-
-•
c
100
o
"u
c
o
kT
f\
-
c
3
.._
•
\
=174.84 eV
1
Detector 3
Angle -
180
10
\•
in
'"O
1
r
\
—
•
\
1000
2000
3000
4000
5000
Energy (eV)
Figure 26
Distribution versus Energy
59
— April
19
— 10:40:38
UT
—
19-APR-90
10
C
•I
'
10:49:14 UT
"""i
0.37 cm"
n
•
'
i
•
-3
•
180
859.74 eV
•
(
10
Angle =
.
kT =
•
•
D 3
•
•
•
•
£
•
•
7
10
•
•
•
10'
•
-
-
c
•
•• •
a;
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—^--*»
10
v
%v»
\ •
10
\
-2
1
Figure 27
«
j
.i
10
100 1000 10000
Energy (eV)
1
Distribution versus Energy
60
100
1000
10000
Energy (eV)
— April
19
— 10:49:14
UT
19-APR-90
1000
10:49:14
.
i
,
n(V)
=
;
.
,
i
0.37
cm
-3
•
c
100
o
;
kT
•
u
c
Detector 3
•
D
• •
C
o
-859.74 eV
Angle -
180
10
jQ
CO
'"D
1
^~"\^
1000
2000
3000
^^
•
4000
5000
Energy (eV)
Figure 28
Distribution versus Energy— April 19
61
— 10:49:14
UT
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
18-APR-1990
1989-046
Field— Aligned
>
l_
a;
c
C
o
u
<v
>
CD
cn
L.
a.
c
LU
c
o
12
8
20
16
TIME(HR)
Log 10 Flux
Electrons
Ions
Plot run
0.5
1.0
0.0
19-Aug-1993 10:34:35.00
Figure 29
1.5
0.5
2.0
1.0
2.5
1.5
Naval Postgraduate School
Energy versus Time Spectrogram for April 18, 1990
62
24
LANL MPA - 1989-046
Detector 3
18-APR-90
8:43:43
- 3270.09 eV
1
- 3270.09 eV
1
3020-
^K
io
jAr.«
^!aH
1
-j
o-
-10-20-
-30
1
-30
-30
30
30
V x (Mm/s)
oq
Diffl
Vi
Enerqy Flux
Loq
(Mm/s)
Dist.
Fen
4.0
10000
7.5
3.5
1000
3.0
en
7.0
L.
c
uj
100
cn
2.5
-^i
2.0 1
10-
r
6.5
1.5
90
180
270
360
6.0
Pitch Angle
Figure 30
90
180
270
360
Pitch Angle
Energy versus Pitch Angle—April 18—08:43:43
63
1.0
18-APR-90
10000
>
i
1
'
'
8:43:43
i
i
t
|
i
;
'
n(V)
7.76 cm'
=
-3
_•
_
•7
r
c
•|
1000
I
kT
-216.25 eV
-
•
^
c
D
Detector 3
^^-
-
c
Angle =
^^^
o
1
8C
-
•
-
.
D
Q
^\^»
100 T
-
XT'
-
10
•
^
..
-
i
1
200
.
400
600
1000
800
Energy (eV)
Figure 31
Distribution versus Energy
64
— April
18
— 08:43:43
1
LANL MPA - 1989-046
Detector 3
18-APR-90
8:46:35
- 3270.09 eV
1
3270.09 eV
30-
2010
^m
BK
(
'^HR^^^^^kI ^B
0]
-10-20-
-30
i
-30
30
30
30
V x (Mm/s)
V x (Mm/s)
Log_
Diffl
_
Energy Flux
Loq
Dist.
Fen
90
180
270
10000
7.5
1000
CH
7.0
en
100
10-
r
90
180
270
360
6.5
6.0
Figure 32
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle—April 18
65
— 08:46:35
,
10
18- -APR- 90
8
8:46:35 UT
= 20.66 cnn"
n
.
""'
8.5
i
Angle =
•
kT =
•
10
6
125 .97 eV
•
8.0
D3 ^
:
"
•
LJ
*
•
^
•
-
1
••,
>»,.»«k
s.
/•
N
•
180
/•
•
,J
,,..,
''
— —
7.5
/*
X
3
/
•
^
>.
\
\
•
/ •
•
i
/
•
i
/
•
7.0
/
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en
10
2
l.
/
<u
/
\
c
•
\
\
•
1
•
/
i
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•
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/
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10°
•
•
i
-
6.C
•
\
/
•
1
r
•
*
i
•
/
^~
\*
*
•
/
6.5
*•
I
*
/
<
2
1C
,
.
5.5
\
i
10
100 1000 10000
Energy (eV)
Figure 33
,
1
/..ll
10
Distribution versus Energy
66
,,
.1
100
1000
10000
Energy (eV)
— April
18
— 08:46:35
18- -APR
10000
:
\
-90
|
i
i
i
|
i
:
i
n(V)
i
=
9.34
Ac celerot ng Potential
•
•\^
c
o
u
8:46:35
i
i
kT
=
cm
-3
-
100.0 V
= 125.97 eV
-
1000
Detector 3
c
Angle =
C
180
o
01
-
100
•\
10
i
200
i
400
600
1000
800
Energy (eV)
Figure 34
Distribution versus Energy
67
— April
18
— 08:46:35
LANL MPA - 1989-046
Detector 3
8-APR-90
8:49:27
- 3270.09 eV
6
- 3270.09 eV
1
—101
>
-2CH
-30
30
-30
30
V x (Mm/s)
Loq
i
JL
Enerqy Flux
Diffl
i
,
V x (Mm/s)
,
i__.
2A
,
Loq
Dist.
Fen
90
180
270
u__i
10000
90
180
270
360
6.0
Figure 35
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle--April 18—08:49:27
68
—
_
8-APR-90
'
!
'
1
8:49:27 UT
'
= 16.39
n
""'
8.5
cm
Angle =
127.24 eV
-
/
•
•
u
•
•
7.5
•
10
/
/ •
•
*~i
•
•
•
\
\
A
•
/
—^^\
-—
180
D 3
8.0
•
10*
""'
""'
'
•
kT =
'
/
••••••^\
*
/
••
1
7.0
en
•
/
/
c
•
6.5
10
/
•/
•
\
•
1
6.0
r
.
'
•
\
•
1
5.5
1
100 1000 10000
Energy (sV)
10
Figure 36
•
i
».
\
I
•
/
-
,-2
i
1
•
•
\
•
•
/
\m
v
!•"
/
•
<v
10'
•
/
Distribution versus Energy
69
100
1000
Energy (eV)
— April
18
10000
08:49:27
18- -APR-90
10000
i
1
-
n(V)
N.
•
i
8:49:27
i
|
.
,
.
,
i
=
7.47
cm -3
:
-•
Accelerating Potential =
••
-
•••
•
-
c
Q
o
c
D
100.0 V
\
kT
1000
\
Detector 3
Angle =
N.
C
=127.24 eV
180
-
o
O
100
:
C
•
>.
-
X.
10
•
1
200
400
600
1000
800
Energy (eV)
Figure 37
Distribution versus Energy
70
— April
18
— 08:49:27
LANL MPA - 1989-046
Detector 3
18-APR-90
8:52:19
- 3270.09 eV
s
— 10
3270.09 eV
i
-30
30
-30
30
V x (Mm/s)
V I (Mm/s)
Log
Diff
I
Energy Flux
Loq
Dist.
Fen
90
180
270
100007.5
1000
en
c
UJ
7.0
100
10-
r-
90
180
270
360
6.5
6.0
Figure 38
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle—April 18—08:52:19
71
_
18-APR-90
10
8
i
=
n
5.42
kT =
10
6
•
cm" 3
,...,
""'
Angle =
180
D 3
8.0
•
-
•
N
LJ
•
£
•
10
8:52:19 UT
81 .16 eV
•
10
'
8.5
"i
i
4
•
^\
CP
•
/
QJ
\
C
/
•
•
/ •
1)
6.5
•
\
*•
\
~o
•
•
\
•
\
*/ •
6.0
\
/•
•
\
1
4
-J
100 1000 10C00
Energy (eV)
Figure 39
*
t, 7.0
\
10' 2
/•
/
•
\
10
•
X
3
•
?
-
7.5
.
«J
Xi
10
Distribution versus Energy
72
i
100
1000
Energy (eV)
— April
18
10000
— 08:52:19
18-APR-90
8:52:19
10000F
n(V)
=
2.02
Accelerating Potential =
kT =
c
°
u
1
cm
-3
80.0 V
81.16 eV
000
Detector 3
c
D
Angle =
C
180
o
D
JO
200
400
600
1000
800
Energy (eV)
Figure 40
Distribution versus Energy
73
— April
18
— 08:52:19
1
18-APR-90
8:55:1
1
UT
g
=
n
1
.29 cm"'
•
kT 10
6
129.28 eV
•
•
•
•
10
4
•
•
•
•
••
•
10
~*V
?
\ •
'•
\
10
•
\
•
\
•
\
\
10'
i
2
5.5
100 1000 10000
Energy (eV)
10
Figure 41
1
10
t
Distribution versus Energy
74
100
1000
Energy (eV)
— April
18
10000
— 08:55:11
18-APR-90
10000
i
8:55:11
'
i
-»
'
i
=
n(V)
i
cm
1.29
-3
-
c
o
o
c
D
*
1000 —
kT
=129.28 eV
-
•
Detector 3
Vv
•
Angle =
C
180
-
o
D
100 -
-
•s.
-
10
i
200
.
,
i
.
400
.
X
i
600
.
•
.
.
i
1000
800
Energy (eV)
Figure 42
Distribution versus Energy
75
— April
18
— 08:55:11
Los Alamos National Laboratory Magnetospheric Plasma Analyzer
1989-046
12-APR-1990
Field-Aligned
>
c
c
O
*^
u
a;
Ld
>
c
c
o
12
20
16
TIME(HR)
Log 10 Flux
Electrons
Ions
Plot run
0.5
1.0
0.0
22-Sep-1993 17:24:09.00
Figure 43
1.5
0.5
2.0
1.0
2.5
1.5
Naval Postgraduate School
Energy versus Time Spectrogram for April 12, 1990
76
24
LANL MPA - 1989-046
Detector 3
12-APR-90
5:21:08
- 3270.09 eV
1
3270.09 eV
30-
2010
-
o-
-10-20-
Jt
'
\
m~ v AQl - -ifB
flip ^^p^
:
"
1§
*
<
^%
-30-30
-30
30
30
V x (Mm/s)
V x (Mm/s)
Loq
Diffl
Enerqy Flux
10000
Loq
Dist.
Fen
90
180
270
7.5
1000
7.0
en
0)
c
100
Ld
6.5
6.0
90
180
270
360
Figure 44
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle—April 12—05:21:08
77
—
12- -APR-90
~8
10°
.,.,
28.47 cm"
n
kT =
10
6
5:21: 8 UT
,
3
Ang'e =
53.53 eV
D 3
••
-
•
•
•
•
»•
x
TO
8
4
en
^O
2
u
i
7
\»
•
i
10°
**
\
•
i
•
i
•
,-2
10
i
,,„i
•
,
10
100
1000 10000
1
10
Energy (eV)
Figure 45
100
1000
10000
Energy (eV)
Distribution versus Energy
78
— April
12
05:21:08
-
12- -APR-90
^6
10
,
.
5:21: 8
,
|
i
i
n(V)
= 13.49 cm" 3
\
•
10°
5V
c
kT
•
c
u
c
3
Acceleroting Potentiol =
10
40
V
4
= 53.53 eV
:
Detector 3
-=
Angle =
C
o
•
D
-
•
10
-
>
3
•^\
:
To
1C
2
—
>v^ •
:
-
X
1
.o
_l
1
1
i
.
.
,
i
600
400
200
Energy (eV)
Figure 46
Distribution versus Energy
79
— April
12
— 05:21:08
'
LANL MPA - 1989-046
Detector 3
12-APR-90
5:24:00
- 3270.09 eV
1
- 3270.09 eV
1
30:
20^
10-
o-
-10-20-
&HM*>
K^^PI^f
^H
*"*'"'
^U.~*./
-30-
30
-30
30
30
V x (Mm/s)
V x (Mm/s)
Loq
Diffl
Enerqy Flux
10000
Loq
Dist.
Fen
90
180
270
7.5
1000
5^
7.0
ex.
c
CP
V
c
100
6.5
90
180
270
360
6.0
Figure 47
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle—April 12—05:24:00
80
12-APR-90
10
—5:24:
(
i
'
UT
'""I
1CT
10
10'
10^
10
100 1000 10000
Energy (eV)
10
Figure 48
10
Distribution versus Energy
81
100
1000
Energy (eV)
— April
12
10000
— 05:24:00
12- -APR-90
~6
10°
i
5:24: Q
i
i
|
i
i
i
\
»\
10
5
Accelerating Potenticl =
^^
c
o
u
c
D
kT
io
= 29.18 c-d~
n(V)
4
5
-
50.0 V
= 33.83 eV
\
Detector 3
-
Angle =
c
o
r
.0
10
3
"
\
10
2
•
\
r
~
\
:
10
-
•
•
1
i
,
,
,
\
i
400
200
600
Energy (eV)
Figure 49
Distribution versus Energy
82
— April
12--05:24:00
LANL MPA - 1989-046
Detector 3
12-APR-90
5:26:52
- 3270.09 eV
1
-30
3270.09 eV
30
-30
30
v i (Mm/s)
V x (Mm/s)
Loq_
Diffl
Energy Flux
Loq
i
10000-
~>
Dist.
Fen
i
i
7.5
10007.0
6.5
90
180
270
360
6.0
Figure 50
90
180
270
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle— April 12—05:26:52
83
1
_
12- -APR- -90
~8
10
58.88 cm"
n
kT 10
5:26:52 UT
"I
49.80 eV
5
••
"•T^
<o
•o
4
-
2
-
-
•
\
•
i
I
-o°
i
•
•
•
,-2
10
•
,,„i
,
i
100 } 000 10000
Energy (eV)
10
Figure 51
1
10
Distribution versus Energy
84
100
1000
Energy (eV)
— April
12
10000
— 05:26:52
12-APR-90
1
"T
*
5:26:52
1
|
[
n(V)
1
1CT
7
= 17.65
Acceleroting Potential =
cm
-3
:
60.0 V
MUIU
c
1
1
o
v
-
O
5
A
4
10 -
kT
.
>v»
-
X.
Detector 3
N.
c
-
= 49.80 eV
-
Angle =
;
\
o
1
10
3 —
—
T3
10'
'-
:
•
10
I
,
,
1
,
200
600
400
Energy (eV)
Figure 52
Distribution versus energy
85
— April
12
— 05:26:52
LANL MPA - 1989-046
Detector 3
12-APR-90
- 3270.09 eV
1
s
5:29:44
- 3270.09 eV
1
-10
•30
-30
30
30
V x (Mm/s)
V x (Mm/s)
Log
Diffl
Energy Flux
0000
Loq
Dist.
Fen
90
180
270
7.5
10007.0
en
100
6.5
90
180
270
360
6.0
Figure 53
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle—April 12—05:29:44
86
_
12-APR-90
10
C
'1
'
'
=131
n
5:29:44 UT
"""
.00
3
cm
Angle =
•
kT
=
51 .67 eV
D 3
•
10
(
•
/ •
•
x
10
-
•
•
/
-
•
/
\
U
"D
*
10'
\
•
/
/
10'
•
/
8
\
•
O
••
A.-
I
•
•
•
•
•
•• ••
•
•
10'
.
i
i
i
10
100
i
1000 10000
.
100
1000
Energy (eV)
Energy (eV)
Figure 54
i
Distribution versus Energy
87
— April
12
10000
— 05:29:44
12- -APR-90
~6
10
1
i
1
10
c
3
• •
'
^\«
kT
4
= 27.85
cm
-3
-
80.0 V
- 51.67 eV
-
Angle =
>v
:
Detector 3
C
O
10
=
Accelerating Potential =
:•
10
n(V)
5
c
o
o
5:29:44
i
:
3
-
~
-
^^
"O
10
2
-.
\
•
-
-
^o
1
1
,
,
.
1
400
200
600
Energy (eV)
Figure 55
Distribution versus Energy
88
— April
12
— 05:29:44
J
as
*\
,
in
EVANS, 1974
LOGE*^
Figure
5.
and how
A
/
/
/
/
A representation of a discrete
auroral structure (panel
A)
a displacement of the potential could allow auroral albedo
electrons to be injected into the magnetosphere (panel B).
Figure 56
Acceleration Potential Structure, Klumpar (1989)
89
LANL MPA - 1989-046
Detector 3
17-APR-90
1
-
-
11:13:27
3270.09 eV
3270.09 eV
302010
-
^^L
^^^WPIP^
o-
-10-20-30-30
-30
30
30
V i (Mm/s)
V i (Mm/s)
Log
Diffl
Energy Flux
10000
Loq
Dist.
Fen
90
180
270
7.6
7.4
1000
en
7.2
100
7.0
6.8
90
180
270
360
6.6
Figure 57
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle
90
— April
17,
1990
LANL MPA - 1989-046
Detector 3
17-APR-90
12:30:52
- 3270.09 eV
1
- 3270.09 eV
1
30-
30
i
20
|
10-
-
|
0i
BB^-
.
-jflfc
r
;
20^
10
i
B
W
0^
J&BM
10f
—10
-1
-20-
20^
f
30f
-30
30
-30-
-30
30
VI (Mm/s)
V i (Mm/s)
Log
Diffl
Energy Flux
Log
Dist.
Fen
4.0
10000
7.6
3.5
7.4
7.2
3.0
7.0
2.5
6.8
90
180
270
360
6.6
Figure 58
90
180
270
360
Pitch Angle
Pitch Angle
Energy versus Pitch Angle—April 17, 1990
91
2.0
LIST OF REFERENCES
Magnetospheric Plasma Analyzer for Spacecraft with
Constrained Resources Review of Science Instrumentation,
Bame, S. J.
,
,
Vol. 64, No. 4, p.
1026, April,
1993.
Eather, R.H.
S.B. Mende, and R.J.R. Judge, Plasma Injection
at Synchronous Orbit and Spatial and Temporal Auroral
Morphology Journal of Geophysical Research, Vol. 81, No.
16, p. 2805, June, 1976.
,
,
A. Nishida, and T. Terasawa, Bi-directional Electron
Pitch Angle Anisotropy in the Plasma Sheet, Journal of
Geophysical Research, Vol. 86, No. A13, p. 11,211,
December, 1981.
Hada, T.
,
E.W.Jr., J.R. Ashbridge, S. J. Bame, and S. Singer,
Energy spectra and angular distributions of particles in
the plasma sheet and their comparison with rocket
measurements over the auroral zone, Journal of Geophysical
Research, Vol. 76, No. 1, p. 63, January 1971.
Hones,
Johnstone, A.D., D.M. Walton, and R. Liu, Pitch Angle
Diffusion of Low-Energy Electrons by Whistler Mode Waves,
Journal of Geophysical Research, Vol. 98, No. A4 p. 5959,
April, 1993.
,
Klumpar, D.M. J.M. Quinn, and E.G. Shelley, Counter-Streaming
9
Electrons
at
the
Geomagnetic
Equator
Near
RE
Geophysical Research Letters, Vol. 15, No. 11, P. 1295,
October, 1988.
,
,
Klumpar, D.M.
Near Equatorial Signatures of Dynamic Auroral
Processes
in Physics of Space Plasmas, edited by T.
Crew,
Jasperse,
Scientific
Chang,
G.B.
and
J.R.
Publishers, 1990.
,
,
Lin,
C.S.,B. Mauk,G.K. Parks, S. DeForest, and C.E. Mcllwain,
Temperature Characteristics of Electron Beams and Ambient
Particles, Journal of Geophysical Research, Vol. 84, No.
A6,
p.
2651, June,
1979.
Lin, C.S., J.L. Burch, J.D. Winningham, and J.D. Menietti, DE1
Observations of Counterstreaming Electrons at High
Altitudes Geophysical Research Letters, Vol. 9, No. 9, p.
925, September, 1982.
,
92
,
B., and C.E. Mcllwain, ATS-6 UCSD Auroral Particles
Experiment, IEEE Trans. Aerosp. Electron. Syst.
AES-11,
Mauk,
,
p.
1125,
1975.
McComas, D.J., Magnetospheric Plasma Analyzer (MPA) : Initial
Three-Spacecraft Observations from Geosynchronous Orbit,
Submitted to Journal of Geophysical Research, November,
1992.
Mcllwain, Carl E.
Auroral Electron Beams Near the Magnetic
Equator, in Physics of the Hot Plasma in the
Magnetosphere, edited by B. Hultqvist and L. Stenflo, p. 91,
Plenum, New York, 1975.
,
Mende, S.B., and E.G. Shelley, Coordinated Electron Flux and
Simultaneous Auroral Observations Journal of Geophysical
Research, Vol. 81, p. 97, 1976.
,
Mizera, Paul F. and Joseph F. Fennell, Signatures of Electric
Fields from High and Low Altitude Particles Distributions
Geophysical Research Letters, Vol. 4, No. 8, p. 311,
August, 1977.
,
,
and
Pitch
Angle
T.E.,
R.L.
Arnoldy,
Plasma
Distributions Near the Substorm Injection Front, Journal
of Geophysical Research, Vol. 87, No. Al, p. 265, January,
Moore,
1982.
Parks, G.K.,C.S. Lin,B. Mauk,S. DeForest,and C.E. Mcllwain,
Characteristics of Magnetospheric Particle Injection
Deduced From Events Observed on August 18, 1974, Journal
8
of Geophysical Research, Vol. 82, No. 32, p. 5 2
November, 1977.
,
Parks, G.K., B. Mauk, C. Gurgiolo, and C.S. Lin, Observations
of Plasma Injection, in Dynamics of the Magnetosphere,
edited by S.I. Akasofu, p. 371, D. Reidel, 1979.
Tascione, Thomas F.
Introduction to the Space Environment
p. 45-100, Orbit Book Company, 1988.
,
Tetreault, David, Theory of Electric Fields in the Auroral
Acceleration Region, Journal of Geophysical Research, Vol.
No. A3, p.
3549, March,
1991.
93
9
INITIAL DISTRIBUTION LIST
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Copies
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