Author(s)
Lowery, Donald Ray.; Olsen, Richard C.
Title
Survey of the Air Force P78-2 (SCATHA)--satellite plasma wave data during electron
gun operations.
Publisher
Issue Date
1987
URL
http://hdl.handle.net/10945/22530
This document was downloaded on May 04, 2015 at 22:09:29
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ilix.\,-
NAVAL POSTGRADUATE SCHOOL
Monterey , California
THESIS
Survey of the Air Force P78-2
(SCATHA)
Satellite Plasma Wave Data During
Electron Gun Operations
by
Donald Ray Lowery
December 1987
Thesis Advisor:
R.C. Olsen
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ELEMENT NO.
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NO
ACCESSION NO.
UNIT
ITLE (Include Security Classification)
OF THE AIR FORCE P78-2
iCTRON GUN OPERATIONS
.VEY
(SCATHA)
SATELLITE PLASMA WAVE DATA DURING
'ERSONAL AUTHOR(S)
ery,
Donald
TYPE OF REPORT
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1987 December
lUPPLEMENTARY NOTATION
COSATI CODES
FIELD
GROUP
18.
SUBJECT TERMS (Continue on reverse
if
necessary
and
identify by block
number)
Satellite, SCATHA, Electron Cyclotron Frequency,
gyrof requency Stimulated Plasma Waves, Electron
Beam, Electron Gun
SUB-GROUP
,
ABSTRACT (Continue on reverse
if
necessary
and
identify
by block number)
The Air Force P78-2 satellite, known as SCATHA, was designed to study
cecraft charging processes at geosynchronous orbit. This thesis examines
plasma wave data taken during two periods when active experiments were
ducted with the electron gun. Emissions at the electron gyrof requency
e stimulated by the operation of the electron gun on some occasions. These
icate interaction between the electron beam and plasma at local resonant
quencies of the plasma.
A major objective of this thesis is to catalogue the characteristics
the plasma wave data common to the modes of operation of the electron gun.
purpose is to provide a baseline for analysis of data not only from
THA, but from other spacecraft including the space shuttle orbiter.
mulated emissions at characteristic frequencies dependent on gun current
voltage were identified. These were consistently observed during the
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Approved for public release; distribution is unlimited.
Survey of the Air Force P7a-2 (SCATHA) Satellite Plasma
Wave Data During Electron Gun Operations
by
Donald Ray Lowery
Lieutenant Commander, United States Navy
B.S.E.E. North Carolina State University, 1975
Submitted in partial fulfillment of the
requirements for the degree of
MASTER OF SCIENCE IN ENGINEERING SCIENCE
from the
NAVAL POSTGRADUATE SCHOOL
December 1987
^C'^-^
'S^^
"c'^
ABSTRACT
The Air
designed
Force P7B-E
study
to
geosynchronous
wave
experiments
charging
processes
at
This thesis examines the plasma
during
were
periods
two
conducted
the electron
Emissions at
by the
spacecraft
orbit.
taken
data
satellite, known as SCATHA, was
with
the
active
when
electron
gun.
gyrof requency were stimulated
the electron gun on some occasions.
operation of
These indicate interaction between the electron
beam and
plasma at local resonant frequencies of the plasma.
A major
objective of this thesis is to catalogue the
characteristics of the plasma
modes of
operation of
to provide a
SCATHA,
wave
data
the electron gun.
baseline for analysis of data
from
but
shuttle orbiter.
other
common
The purpose is
not only from
spacecraft including the space
Stimulated
emissions at characteristic
current and voltage were
frequencies
dependent
identified.
These were consistently observed
experiment presented
not displayed.
on
to the
gun
during the
here, and other events analyzed but
TABLE OF CONTENTS
ABSTRACT
4
LIST OF FIGURES
6
LIST OF TABLES
9
CHAPTER
INTRODUCTION
I.
10
A.
PROBLEM OF SPACECRAFT CHARGING
B.
EXPERIMENTS
CHAPTER II.
.......
10
12
THE SCATHA PROGRAM
17
A.
SATELLITE DESCRIPTION
17
B.
ELECTRON GUN
20
C.
SClO/SC-1 DETECTORS
21
CHAPTER III.
OBSERVATIONS
A.
EO JULY 1979
SE^l-SSSO UT
B.
3
APRIL 1979
1*^13-1^36 UT
C.
OTHER OBSERVATIONS
CHAPTER IV.
APPENDIX.
2 3
.
23
.
CONCLUSIONS AND RECOMMENDATIONS.
48
78
...
81
TABLES
84
LIST OF REFERENCES
89
INITIAL DISTRIBUTION LIST
92
LIST OF FIGURES
Page
No.
I.
Figure I-l
Local time plot of satellite
operations anomalies
.
11
SCATHA space vehicle (P7a-2)
..18
S.
Figure II-l.
3.
Experiment and boom locations on
Figure II-E.
the SCATHA satellite
19
Narrowband electric and
Figure IIIA-1.
magnetic receiver data for 20 July 1979
24
^.
5.
6.
7.
8.
9.
10.
II.
12.
.
.
....
Spectrogram showing typical
Figure IIIA-2.
plasma wave data
25
Figure IIIA-3. Electron gyrof requency
measured at E590 Hz at 22:50:50
27
Figure IIIA-*^.
Naturally occurring
electron cyclotron waves are present.
Effect of electron gun being turned
on is seen at 22:55:00
30
Monochromatic signal similar
Figure IIIA-5.
to the fee wave seen in the plasma wave data
.
.32
Figure IIIA-6.
Spectrogram for 22:57 to
23:02.
The monochromatic signal drops below
the gyrof requency at 22:59:00
33
Figure IIIA— 7.
Spectrogram shows spectra
with the electron gun on at 10 hA, 50 volts.
Gun current was briefly increased to 100 HA
between 23:02:28 to 23:03:15
35
Figure IIIA-8.
Spectrogram shows change in
plasma wave data when gun was turned off at
23:07:'^!
37
Figure IIIA-9.
Repeatability of the effects
of the electron gun operation is seen when the
beam was reenergized at 23:18:31
38
13.
Figure IIIA-10. Electron beam is turned off at
23:23:'^a.
The interference lines at 700, 1-^00
and ElOO Hz return
40
1^.
Figure IIIA-11.
Sporadic electron gyrof requency
emissions present in the electric receiver data;
electron gun is off
41
15.
Figure IIIA-12.
(top) Plasma wave oscillation
with gun on. (bot) Solar array current modulated
at the satellite spin period
43
16.
Figure IIIB-1.
50 volts
17.
18.
10 HA,
51
Figure IIIB-E.
Magnetic receiver frequency
spectrum taken at 1^:13:21 on 3 April 1979.
Interference lines are present at 700, l<4-00,
ElOO and 3000 Hz.
The electron gun is off.
1
HA;
50,
1
ha;
.
500,
.52
54
Spectrograms for beam current
1500 and 3000 volts
56
150,
Figure IIIB-^.
of
.
Spectrograms for beam current
and 300 volts
Figure IIIB-3.
of
19.
Beam on at 1^:1^:0^,
20. Figure IIIB-5.
Magnetic receiver spectrum with
electron beam on at 1 HA, 500 volts.
The 700
and ElOO Hz tuning fork interference lines are
the most prominent features
57
Spectrograms for beam current
21. Figure IIIB-6.
of 10 HA; 50, 150 and 300 volts
59
Spectrograms for beam current
1500 and 3000 volts
62
22. Figure IIIB-7.
of 10 HA; 500,
23.
2^^
.
Figure IIIB-8.
Spectra taken while receiver
is tuned to the magnetic receiver.
The beam
is on at 10 HA, 500 volts
Figure IIIB-9.
100 HA; 50,
64
Spectrograms for beam current of
150 and 300 volts
66
25. Figure IIIB-10.
Magnetic receiver spectrum
showing a sporadic signal (probably natural) at
•^^80 Hz.
Beam is on at 100 HA, 5 volts
67
Plasma wave harmonic structure.
Spectrogram taken at 1^:31:1E. Gun is on at
69
100 HA, 500 volts
26. Figure IIIB-11.
Magnetic receiver frequency
spectrum of the harmonic structure seen in
Electron beam is on at 100 HA,
Figure IIIB-9c.
150 volts
70
Spectrogram of focus change
28. Figure IIIB-13.
from low to medium at 1^:32:30 for beam current
of 100 hA and beam voltage of 300 volts
72
27. Figure IIIB-12.
29. Figure IIIB-l"^.
of 100 HA; 500,
Spectrogram for beam current
1500 and 3000 volts
Spectrogram of focus change
from medium to high at 1'^-: 15:05 for beam
current of 1 HA and beam voltage of 50 volts
73
30. Figure IIIB-15.
.
.77
LIST OF TABLES
Page
No.
1.
Table I.
List of" scientific experiments
on the SCATHA satellite
2.
Table II.
3.
Table III.
SC4-1 commands for 3 April
^.
Table IV.
emissions
Summary of the commonly seen
SC^-1 commands for EO July 1979
1979
84
.
.
.
85
.86
.88
INTRODUCTION
I.
A.
PROBLEM OF SATELLITE CHARGING
1
Satellite Charging
.
Satellite
electrical charge
become
charging
potentials
imbalance between ambient electron
currents
generated
Spacecraft
electrons.
(DeForest,
(Olsen,
The
1985).
linked
on
the
to
changes that have
several
past
attributed to
arcing
on
(Garrett,
1972),
induced
been
charging
several satellites
observed on
the
satellite
occur
due to an
currents and
and ion
photoemission
by
of
use
the
in
negative
Large
systems.
issue
and
effects
over the
1981),
of static
satellites and has
surface of
on the
important
an
buildup
the
is
secondary
have
been
past few years
(Grard,
1983)
and
large negative potentials that have
geosynchronous
satellites
have
been
satellite failures and unexpected mode
been
years.
observed
periodically
over the
anomalies can be directly
These
spacecraft charging
effects, which create
satellite surface, resulting in material
breakdown and subsequent failure of the satellite. Figure
I-l
shows
the
correlation
between
10
observed satellite
LOCAL TIME DEPENDENCE OF ANOMALIES
7 osp \c^(. uPsers
O »SCS U nOA UPSETS
T
INietSAT
O tNT»\.$Al
iV
III
Figure I-l. Local time p.ilot of satellite
operations anomalies.
11
,
anomalies and the satellite
1983).
It
local
midnight
concern
immediate
of
to
1981).
j
EXPERIMENTS
1.
As a result of satellite charging effects, active
potential control
by use of ion
(Glsen,
1985)
designed to
on ATS
(Olsen,
program
SCATHA
The
1981) and
was specifically
study the effects of spacecraft charging and
environment
designed experiments.
with the
sources
attempted
and on SCATHA using an electron beam source
determine the effects
satellite
5 and ATS 6 has been
electron
and
1987).
(Dlsen,
to
dawn period.
the effect of satellite
is
charging on plasma measurements (Garrett
B.
et al
be seen that a majority of the satellite
can
anomalies occurred during the
Also
(Grard,
time
satellite and
on the
through
In
a
series
of
particular, this
the near
carefully
thesis deals
plasma wave observations during SCATHA electron
gun experiments.
in the published
Reports
on such
observations ars rare
literature.
Stimulated plasma waves in the VLF range are reported
by Akai
Japanese
(ISAS RN285) and Kawashima, et al,
satellite,
Jikiken
(EXOS-B).
experiments were conducted to
study the
(1976) for the
Electron
gun
wave excitation
phenomena (both linear and non-linear) due to beam-plasma
12
interactions,
electron
and
beam
emission.
stepped
was
increments.
.
from
The plasma
potential
E5 mA increments.
100
waves
The gun
to EOO volts in E5 volt
were
classified
based on the L-region in which they were observed.
electron
at the
by
The electron gun current was
stepped from .25 - 1.0 mA in
voltage
satellite
control
to
gyrof requency
and
by type
Waves
harmonics, the
its
upper hybrid resonance frequency and the plasma frequency
were observed.
Kawashima, et al
beam experiments
11
VLF and
plasma heating
and electrostatic
al,
(1987)
operations
(1982) reported results of electron
from ionospheric sounding rockets K-10-
and K-lO-12.
beam and
,
were excited
was observed
in
analyzer measurements.
reported VLF
on
HF waves
the
Langmuir probe
Kawashima, et
by electron beam
waves excited
Japan-US
rocket
tether
by the
experiment
CHARGE-2.
Koons
and
Cohen
reported
(1982)
electrical discharges stimulated by
SCATHA
.
Correlation between
a
plasma waves and
an electron
beam on
change in gun parameters
Electrostatic
and a change to
the spectrum
emissions above
the electron gyrof requency were detected
on the electric antenna.
13
was noted.
of 10-60 HA
Experiments on ISEE-1 used beam currents
and
energies
beam
of
eV
O-'^O
This is comparable to
,
Lebreton,
SCATHA data we will present.
et
al
(19Q2)
,
reported the enhancement of the electric wave spectrum by
No clearly
the injection of an electron beam on ISEE-1.
identified resonances were reported.
Matasumoto,
phenomena in
et
the
sounding rocket
used to
al
emissions
non-linear
the
ionospheric
the
in
frequencies
at
observed
new
on
wave
the Japanese
by
A low energy electron beam was
K-9M-''tl.
investigate
interactions
range
VLF
reported
(1975)
,
and particle
wave
Triggered
plasma.
around
hybrid
lower
the
resonance frequency were found.
Plasma
heating
as
result
a
of
injections is discussed in Margo t-Chaker
The experiment
that electron
al
,
(19S6).
auroral arc.
It
was shown
beam plasma interactions in the 200-250 km
ionosphere resulted in
currents were
et
beam
on a Black Brant V rocketj
was conducted
AAF-NVB-06 fired through an
j
electron
1,
electron
strong
10
and 100
at
the
mA and
heating.
Beam
beam voltages were
1.9, ^ and 8 kV.
Plasma waves
electron
gyrof requency
discussed by
frequency
plasma
generated
Bernstein, et
al,
14
in the
(1975).
and
at the
laboratory are
Electron beam-
plasma
interaction
briefly
only
is
discussed.
laboratory data was of interest, but tended to
the
beam-plasma
This
deal with
which involves a neutral gas
discharge
background, not our case.
There have been
naturally
reports
few
emissions
occurring
relation for
or near the electron
at
gyrof requency (Koons and Edgar,
literature of
the
in
The dispersion
1985).
electron gyrof requency
harmonic waves does
not have a solution at exactly the gyrof requency
(1985) report
and Edgar,
VLF receiver
electron
on
SCATHA
gyrof requency
detection of
and
at
just
theories could not account
above
the local
that present
waves that
for the
Koons
emissions by the
concluded
They
.
.
were the
subject of their report.
will examine
This thesis
the plasma wave data taken
during two periods when active experiments with the SC^-1
electron
gun
were
being
conducted.
effect the
The
operation of the electron gun has on the plasma wave data
is
described
in
an
attempt
comparison of future data
other spacecraft
are made
to
plasma wave
not only
including the
distinguish
data that
provide
to
those
baseline for
for SCATHA,
space shuttle.
characteristics
are generated
15
a
but for
Attempts
of the
or affected by the
electron
gun
occurring.
the electron
operations
from
those that ars naturally
Identification of plasma waves
beam at
stimulated by
or near the electron gyrof requency
were a major focus of this investigation.
1«
II
A.
THE 5CATHA PROGRAM
.
SATELLITE DESCRIPTION
1.
5CATHA Satellite
The Air Force P78-S satellite (Figure II-l), known as
SCATHA for
Charging
Spacecraft
at_
High
Altitudes was
January 1979 to study causes and dynamics of
launched in
processes
spacecraft charging
The satellite
geosynchronous orbit.
at
into a nearly geosynchronous
was launched
orbit with a period of E3 5 hours at an apogee
of 7.3 Re
.
The satellite is cylindrical
and a perigee of 5.8 Re.
shape measuring approximately 1.75
meters wide.
It
meters long
is spin stabilized at about
in
and 1.75
1
rpm with
the spin axis in the plane of the orbit and perpendicular
to a
line between the earth and sun.
bellyband and
mostly contained in the
The instruments are
solar cells cover
most of the remaining part of the cylinder (Figure II-S).
Also carried
detectors
on
and
instrument
the
electron
and
described
package
were
potentials
various
existing
near
were particle
guns to be used for
gun experiment
included in the scientific
Also
below.
ion
The electron
charge control experiments.
is
package
instruments
the
17
to
measure
the
spacecraft and to detect
UCSO PLASMA DETECTOR
FORWARD END
GSFC
MAGNETOMETER
Figure II-l. SCATHA Space Vehicle
18
(P78-2)
ANTENNA
I /SC&2
ASSY
VIEW OF
SC9
FORWARD END
SC1-3
-Y
M1127
:^SC7-2
sen
SC2-1
SCI?
SC1M
RADIAL
VIEW
AFT DECK
M123
REF
BAND
/SC5/SC7-3pSC102
M112
4
—
SC7 1SC61 'SCI-4
V
SC10-3 SC2 S SC4
1
SC22
VIEW OF AFT END
Figure II-2. Experiment and boom locations on the
SCATHA satellite.
19
.
wave and particle emissions.
summarized
are
Table
in
The
scientific instruments
and the description of the
I
experiments and the principal investigators are
Fennel
1.
(1982)
Survey
wave
plasma
the
of
active electron beam
thesis.
found in
experiments
generated during
data
are
included
in this
Survey of the plasma wave data generated by ion
gun experiments is the subject of the Master's
thesis of
Lt. Leonard Weddle, USN
The study of spacecraft charging was conducted on the
SCATHA satellite to determine the effect
charging
of
the
satellite
spacecraft potential
periods
of
plasma
and
attempt to control the
active
through
of both natural
experiments.
Two
data generated during electron
wave
beam operations are examined in Chapter III.
B.
ELECTRON GUN
1
.
The
SC^-1 Experiment
electron
designed to
emit a
beam
system
stream of
beam currents and energies.
(SC4-1)
SCATHA
on
electrons over
a
was
range of
The electron beam emitter is
basically a power triode tube consisting of
focusing
heated cathode, control grid,
20
a.rt
indirectly
assembly
and an
.
)
exit anode at satellite ground.
The beam characteristics
are summarized as follows:
Beam current levels <mA):
.001,
Beam energy levels (v): 50,
Beam duty cycles:
100*/,,
t
The higher
kV,
6.25*X
6.0,
1.0,
.1,
300, 500,
150,
1500,
(beam width
13.0
3000
3.9 msec,
16
imes/sec
current settings
restrictions or
.01,
were not
used due to power
operational constraints.
The
13 mA
,
3
mode was locked out due to power limitations and
100*/.
currents above
1
were not
mA
detrimental effect
(Gussenhoven, et al
was noted
on the
routinely used
due to the
the beam had on other instrumentation
,
1937).
Specifically,
severe arcing
satellite surfaces and resulted in the
failure of two of the experiments on S9 March 1979 (Koons
and Cohen,
C.
1982)
SClO/SC-1 DETECTORS
1
.
Associated Detectors
The SC-1 experiment measured VLF and HF emissions and
provided
the
spectrograms.
broadband
data
presented
in
the
The SC-1 experiment employed two antennas,
one for electric field measurements and
21
one for magnetic
The electric antenna was a 100 meter
field measurements.
tip to tip dipole from
experiment.
SCIO
the
The two
halves were extended perpendicular to the spin axis.
inner 30 meters of each 50 meter segment
was coated with
The magnetic antenna was an air core
Kapton insulation.
loop electrostatically shielded with an effective
cross section
at
magnetic receiver
dB
dynamic
sensitivity
was SxlO"-^
range.
was
5x10-''
V/(MHz)*iat 10.5 kHz.
antennas were
day and
progress.
The
when active
1,
sensitivity of the
The
gamma/Hz^ at 1.3 Hz with
for one
charge control
1982)
22
data
to
a
receiver
kHz and lO""'
1.3
at
broadband
The
field
electric
V/(MHz)HL
normally taken
(Fennel
575 m*
1.6 kHz mounted on a two meter boom off
the belly band of the satellite.
60
The
from these
two hours each
experiments were in
OBSERVATIONS
III.
A.
20 JULY 1979
E24 1-2330 UT
Plasma
data
wave
from
this period was analyzed to
determine the effect the electron gun
satellite.
and/or
the plasma
had on
first example will show:
Our
(a)
stimulated emissions at the electron cyclotron frequency,
linkage between the stimulated emissions and the
and (b)
gun operation.
This
example
was
most physically
the
interesting set of observations.
operations during
The gun
to study enhanced
energy noted
fluxes
this period were designed
electrons
of
in earlier experiments.
above
the beam
The gun on-time is
clearly evident in Figure IIIA-1 denoted by the change in
amplitude of
the electric
and magnetic field strengths.
The strength of the signal in
shown to
play an
This
below.
the magnetic
important role
period
has
been
data will be
in explaining
discussed
the data
previously by
Olsen <1987).
This was
a
magnetically
the 2100-2^^00 period.
bulge
at
degrees.
7.5
RE,
The
L=8.1
disturbed day with KP=^ for
satellite
and
was
magnetic
in
the dusk
latitude
of 6
Figure IIIA-2 shows typical plasma wave data in
23
—
SCAT HA
20 JUL 1979
AEROSPACE CORP
SC1°8 RECEIVER
ELECTRIC ANTENNA
T
——————
I
I
I
I
I
-r—
MAGNETIC ANTENNA
I
r
I
'
I
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•
1
h
1
1
40.0
50.0
60.0
70.0
80.0
OQ
3
..
^
§
H
D
5:
5
<
-40.0
kHz
-50.0
-60.0
^|V>,K, j^A |/Sr
-70.0 gl,.
-80.0 H t—i
1—
-40.0
-50.0
-60.0
-70.0 2 W__An^w^v.J^\^ v-rv^
i
-8QS
-40.0
-50.0
-60.0
-70.0
-80.0
22-.00-17
22-00-17
23=0007
1
1
1
1
1-
1
1
I
-I
I
i
1
A^
1
1
—jyj\
23
=
0007
TIME
Figure IIIA-1. Narrowband electric and magnetic receiver
data for 20 July 1979.
24
SCATHA
20 JULY 1979
AEROSPACE PLASMA WAVE RECEIVER
natiural
fc^.
H
0','
y
>;'-•
*s ',
iift>ri(ftiiii11ii)irffriivri
i^f.
il n
».
riirm
2248
>
ii n
M
« r8t
2250
2249
i
) ii
M.
ilSi
'mil
<p
ui
i
ii>i
ii
-
t |> iii i iii
i
i
M\t^'
im
i
irm
ii i
ift
i
jfrn
nmht
2251
TIME
Figure IIIA-2, Spectrogram showing typical plasma wave
data. (The arrow indicates the time for the line plot).
25
<
'
ii i
i
i
spectrogram form for this time period. A spectrogram is a
grey scale presentation of the radio data? as
and frequency.
of time
from
of
signal
For example,
of grey.
and 2.1
in
plotted
black,
as
intermediate values
white* and
kHz in
Figure
Amplitude
DB is proportional to the intensity.
in
High amplitude is
function
vertical axis is frequency
The
The horizontal axis is time.
to 3 kHz.
the
a
low
amplitude as
appear as various shades
intense signals can be seen at 0.7
the magnetic antenna data, denoted by B,
The
IIIA-2.
spectrogram format
and the
Figure
amplitude
of
frequency
the
traditional line plot can be
seen by comparing Figure IIIA-3.
versus
between
relationship
plot
IIIA-3
is an
the data taken at
22:50:50 (indicated by the arrow in Figure IIIA-2).
The
receiver is cycled between the electric (denoted by the E
in Figure
every
seconds.
16
electron
magnetic antennae
IIIA-2) and
cyclotron
Naturally
waves
(fee)
(denoted by B)
electrostatic
occurring
short
(the
vertical
striations between 2250 and 2252) ars observed from about
2.5-2.7 kHz.
occur at
They are identified
the unique
frequency, fee,
the magnetic field data.
as calculated from
interference
fee frequency
At 22:50:50 this
was measured at 2590 Hz (Figure IIIA-3).
2 strong
fact that they
by the
lines
are
26
seen
In Figure IIIAin
the magnetic
o
n)
N
s
o
at
in
CM
+J
n)
o
o
ro
4)
u
e
X
>i
o
c
<u
>
CJ
o
z
u
O
u
a;
0> »-
M
o
u
>1
en
ii.
N 3
0>
<u
U-l
c
O
o
> lO
-J
o
3
-3 in
u
0)
O
(Ni
esi
CVJ
H
M
ro
1
<
H
H
H o
•
in
<U
o
:3
in
en
<-i
(8P)
3anindwv 3Aiivi3y
27
••
i^
b
••
CN
04
:
data
receiver
interference lines Are caused by
been seen
22:50:00
to
These
data.
(Koonsj
et
(Figure IIIA-2)
signals can
(less than 300 Hz)
They are highlighted
in most data-
here for identification purposes
field
appear
been identified,
It
,
19S2).
low frequency
be naturally occurring
to
They
have not
(Note crosstalk-electrostatic
however.
emissions are often
al
in the electric
be seen
signals since they have finite bandwidth.
data.
tuning fork
Hz
been identified previously
These interference lines have
From aSz-^StSO
700
a
These
Hz.
is part of another satellite experiment.
oscillator that
and have
2100
and
1^00
700,
at
observed
magnetic receiver
the
in
likely that the signals we are observing are
is
electrostatic
(Koons,
communication,
1987).
et
1985;
al,
Koons,
private
A summary of the SC^^-l commands is
listed in Table II.
All
the remaining data from this operation is ordered
by fee,
from the
over
and we
use the measured magnetic field strength
fluxgate magnetometer
the
spectra.
computed from
The
the local
to compute
electron
gyrof requency
magnetic field
magnetometer
fee = eB/6.28m
28
and plot fee
was
measured by the
where e
electron charge
is the
the mass of the electron (9.11
magnetic
intensity
field
level on
the worst
10""*^
x
axis (Koons, et al
of the magnetic activity can be
2330
period
strength.
the
in
naturally
The
and
B
m
is
is the
The magnetometer
,
19S5).
seen early
fluctuation
10~"*^eV),
one sigma confidence
nT at
1
x
kg),
gammas.
in
accuracy is estimated to be
(1.602
Evidence
in the 22^1-
of the magnetic field
occurring
electron cyclotron
waves (fcs) which begin in Figure IIIA-2 at 2250 continue
on the next spectrogram
(Figure IIIA-^).
occurring
2252
stripes)
waves
from
neatly
are
to
matched
to
varying gyrof requency overplotted.
computed at
strength
2 second
These waves
the
(faint
vertical
calculated
time
The gyrof requency was
intervals from
plotted
and
225A-
The naturally
the magnetic field
on the spectrograms (small dots).
are similar
appearance
in
with those which
will be induced by the electron gun operations.
At 22:52:^0
and it is
the electron
powered
electron gun
up
at
is turned on.
gun system is initialized,
22:5-^:5'^.
A prompt,
At
22:55:00 the
if muddled,
effect
can be seen on the plasma wave data (Figure IIIA-4).
tuning fork
related interference
The
lines are masked and a
strong broadband signal can be seen in the magnetic field
spectrum.
At 22:55:37 the electron beam is energized at
29
,
SCATHA
20 JULY 1979
AEROSPACE PLASMA WAVE RECEIVER
2254
2255
TIME
Gun on
Figure IIIA-4. Naturally occurring electron cyclotron
waves are present. Effect of electron gun being turned on
is seen at 22:55:00 (arrow).. (The second arrow indicates
the time of the line plot)
30
.
a
current level of 10 HA and 50 eV
continuously in
this mode
The gun was operated
.
until 23:0E:28
when the beam
current was increased to 100 HA.
A monochromatic signals
observed in
similar
data during
the VLF
the gun on in the 10 HA mode.
fee wave,
to the
is
the entire period with
The intense, monochromatic
signal above 2 kHz varied in frequency from about EA-OO to
2600 Hz as seen
This signal
is modulated
frequency
in
spin period of 59 sec, has
a very
appears
the
monochromatic
receiver resolution.
magnetic antenna
in
is
calculated
from
the period after the electron
-
line
a
22:57:00)
electron gyrof requency
,
plot of
(time indicated
The only signal seen in this
the
strength for this time was 2385 Hz.
(22:55:00
data to within
monochromatic signal
the strong,
gyrof requency
The
electric
at 22:56:00
data taken
the satellite
at
narrow bandwidth, and
Figure IIIA-5
by arrow in Figure IIIA-^).
plot is
of Figure IIIA-^.
latter period
in the
the
near 2-^00 Hz.
magnetic field
In the early part of
gun
was
signal
turned on
first
was
at or near the
mimicking the naturally occurring
waves
Figure
IIIA-6
between fee and the
22:58:00.
In
shows
that
significant
signal frequency
particular,
the
31
differences
begin to
occur by
signal frequency drops
a
q
a>
(0
0)
>
(0
0)
o
K-i
0)
o
o
M
td
(0
9 >
CM U
z
3
c
UJ
o
UJ
u.
Oi tr«-
o>
>"
3
o
4J
(0
e
O
^
o
O
o
(1)
c
o
**
1
3
-5
O
o
•H
•
rtJ
-p
TJ
CM
CM CM
in
(D
I
g
<:
(9P)
3anindwv
3Aiiv-i3y
a2
tn
H
H
H
rH
a.
0)
0)
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C
rO
SCAT HA
20 JULY !979
AEROSPACE PLASMA WAVE RECEIVER
X
Ui
D
O
Ui
•-MMMMM
2258
2300
2259
2301
Figure IIIA-6. Spectrogram for 22:57 to 23:02. The
monochromatic signal drops below the gyrof requency at
22:59:00
.
33
substantially
below
gyrof requency
the
22:59:00).
(at
This is significant because it suggests the signal is not
an electron cyclotron wave.
the electron
long as
fluctuation
The
approximately sinusoidal
This
periods.
satellite spin
(at 23:00:30j
period
frequency
close
period (Note
equal
or
to
IIIA-6)
This
characteristic of the
is
signal
signal
the
the location
Figure
arrow in
of
is
repeatable over several
and is
is
spectrogram.
field
for as
gun is operated in the 10 HA mode.
the
in
The signal continues
of the 'knee'
the electric
in
distinguishable
a
appears
and
to the
in
the same
general position on the waveform).
The
effect
of
considered next.
data
will
From
23:02:28
the
gun
parameters
is
A significant change in the plasma wave
result
increased to
changing
to
from
a
23:03:15
change to the gun parameters.
the
gun
beam
current was
100 HA
(Figure IIIA-7).
The VLF data with
the gun on at 100 HA
appeared similar
to the
the electron
beam off.
The strong interference lines at
700 and 2100 Hz reappear in the magnetic
examination of
the data
not
clearly
channel.
Close
shows that some of the sporadic
naturally occurring electron cyclotron
(but
data with
visible
waves are present
in the figure).
34
The intense
SCAT HA
20 JULY 1979
AEROSPACE PLASMA WAVE RECEIVER
,^mce
1t^$
—^
r
2303
I-IOOuaJ
iH-||||ill( rii.yr
2304
2305
2306
TIME
Figure IIIA-7. Spectrogram shows spectra with the electron
gun on at 10 yA, 50 volts. Gun current was briefly increased to 100 yA between 23:02:28 to 23:03:15.
35
.
monochromatic
d
seen
signal
at
beam
HA
10
current
isappears
The
repeatability
the monochromatic signal seen
of
previously is shown by returning the gun parameters to 10
MA, 50
At 23:03:15
volts.
(in Figure IIIA-7)
current was reduced to 10 HA and the
returned
those
to
previously
current (i.e. the E.^-E.7
VLF characteristics
observed
10 hA beam
at
is again present).
kHz signal
remained in this configuration until 23:07:^1
The system
when the
the beam
electron beam
off (Figure IIIA-B).
was turned
The VLF characteristics revert to those observed prior to
the gun operations (prior
and 2100
12
to 22:55:00).
The
the
electric
the magnetic
signals, and
spectra
1-^00
For the next 10-
Hz interference lines return.
minutes
700,
reveal
no
obvious
antenna shows only the tuning
fork lines and receiver noise.
The repeatability of the effects of
operations are
At 23:18:31
emphasized by repetition of the sequence.
the electron beam was
HA beam current.
behavior
the electron gun
shown
again turned
on at 10
The VLF data (Figure IIIA-9) resume the
previously.
The
signal
oscillating
between 2400-2600 Hz returns and the low frequency signal
(100-200 Hz) becomes
23:21:58 the
more
beam current
intense.
From
was increased
36
to
23:21:34 to
100 hA, and
SCATHA
20 JULY 1979
AEROSPACE PLASMA WAVE RECEIVER
8
£
*
""
i~M»i
l«*^'T~TM'illlr»'fi|j.>l.l
>>1
X
>-
u
z
o
Elv§
cr
+
2309
Gun off
2310
2311
TIME
Figure IIIA-8. Spectrogram shows change in plasma wave data
when gun was turned off at 23:07:41.
37
SCATHA
20 JULY 1979
AEROSPACE PLASMA WAVE RECEIVER
X
o
o
2318
2320
2319
2321
,tl
lOOjjA
TIME
Gun on
at
10'
yA
Figure IIIA-9. Repeatability of the effects of the electron gun operation is seen when the beam was reenergized
at 23 18: 31.
:
38
again
2^00-S600
the
interference
reappear
lines
S3:S1:5S the beam current
VLF
regain
data
disappears
signal
Hz
and
the magnetic data.
in
was reduced
now
familiar
character.
E3:23:^8 (Figure IIIA-10> the
electron
beam
off
and
the
their
700,
electron
gyrof requency
(Figure IIIA-11).
operated
at
During the
was turned
Also
data.
emissions were present
period
last
the
gun was
signals can be seen in the
several
HA
10
At
and 2100 Hz interference lines
l-'fOO
could again be seen in the magnetic receiver
sporadic
At
HA and the
10
to
the
magnetic receiver data (e.g. circled arrow at 23:22:30 in
Figure
IIIA-10)
strongly
are
that
suggestive
of
an
intermodulat ion effect in the 2.A--2.7 kHz line.
The 2.'^-E.7 kHz signal that is observed during the 10
HA
mode
operation
of
strongly linked in frequency
is
characteristics to electron cyclotron waves, near but not
at the
natural cyclotron
frequency.
This signal is the
dominant effect that was seen in the VLF data during this
gun operation
and we
of this apparently
The
field
satellite
is
and
a
the
electron
stimulated
broadness
apparent
data
attempt here to explain the source
result
of
processing
signal appears to have a
signal in the magnetic
the
of
finite
39
cyclotron wave.
the
AGC
control
system.
bandwidth,
on the
Although this
it
is most
SCATHA
20 JULY 1979
AEROSPACE PLASMA WAVE RECEIVER
TIME
Figure IIIA-10. Electron beam is turned off of 23:23:48.
The interference lines at 700,1400 and 2100 Hz return.
(The arrow indicates the time of the line plot)
.
40
+>
c
o
*
n
0)
u
ft
to
Ci
lO
lO
emissi
.
ff
o
to
o
C
lO
^^
>-i
(M
N
M-l
X
JC
0)
-H
C
u u
>i -p
o >
OJ
C
z
nH
OJ
tiJ
Z)
U)
-p
.*
o
U
(fl
UJ
(T
U.
OJ
+J
tH
nj
0)
-o
ver
oradic
cei
O
cu
s
<u
r
-11.
trie
m
d
(SP)
aanindwv 3Aiivn3d
41
M
M
H
QJ
i-l
0)
a)
0)
3
-P
•H
C
likely
constant amplitude
itself is the source of the
the satellite
suggests that
observed by the
signal
relatively
The
antenna.
electric
Since the signal is only visible
signal.
current
monochromatic
same
the
determine the propagation of
HA beam
10
beam-plasma effects which
are apparently
there
J
at
the signal
the electric
to
Theory
and magnetic antennas through the ambient plasma.
holds
there
that
should
gyrof requency due
gyrof requency is
to fee?
below
drops
below
the
the
The fact
calculated
the
Since the signal is close
disturbing.
we pursued
signals
no
the dispersion relations.
to
oscillation
the
that
be
was something
there
that
idea
causing the magnetic field strength near the satellite to
One
vary.
magnetic field
that
thing
current?
July 1979.
on 19
array current is the plasma wave
July
The
1979.
solar
array
shadowing
of
the
between the satellite and the sun.
shape
of
the
Figure IIIA-
solar
plasma oscillation is
Isa,
for a 305
oscillation seen
current
cells
solar
satellite
Plotted above the solar
modulated at the satellite spin period.
of
the
is the solar array current.
12 is a plot of the solar array
second period
perturb
might
as
is
on EO
obviously
This is a result
the
booms pass
The similarity of the
current to the shape of the
array
striking.
42
We
suggest
that the
O -P
S-P
d cd
+^ -p
•H oj
'^
O O
E
•H
-p
cd
-p
C
^
rH
H
EH
EH
>
cd
5
EH
<
O
m
0)
•H
o
en
cd
C7N
P.
p:i
<
o
CO
H
cd
H
0)
o +^
P4 CO -H
0)
bo
•H
fi4
43
•H
c
I
BSI
cd
CO
-.-
b3-H£
p.
cd
to
CZH>1)
cd
current causes
solar a,rray
This
magnetic field.
design?
but
perturbation
a
largely balanced
field is
out by
The perturbation field, or
non-zero.
is
to the total
satellite magnetic moment? will vary with the solar array
current*
satellite
strength near the
the electron
change in
Afcecx AB)
perturbation in the magnetic field
The
Isa.
gyrof requency
.
in
a
A
(
slight
Ba
A
Isa,
.
One explanation as to why the
not at
results
then
stimulated signals are
or above the calculated electron gyrof requency is
based on the observations of Isa.
from
calculated
of the magnetic field taken
value
the
gyrof requency was
The
from the fluxgate magnetometer which is at the end of a ^
meter boom
surface.
(0
and
Since the
than the
therefore
is
perturbation
The
moment)
will
magnetometer,
the frequency
value
the satellite
to
it
field
(e.g.
is closer
to the
magnetometer has
the
cyclotron
magnetic
an error
satellite
may be responding to a signal
frequency,
determined by the magnetometer.
of
satellite
stronger near the satellite.
be
magnetic receiver
at the local electron
the
closer
The beam itself begins at the satellite surface
meters).
magnetic
magnetic receiver is at the end of a E
The
meter boom.
field
obtained
estimated to
44
rather than
Note that
from
the
be a few gammas
associated with satellite
generated
private
1987).
communicat ion
»
perturbation in the magnetic
the
order
of
gamma
1
perturbation field of
meters
consistent with
meters and
current
values for the
for
a
correct to
within sensor
for
plasma
the
gyrof requency
only a
I
(
R^at/t
strengths
fields
S00-300
Hz
accuracy.
Hz
is
at E
)^j
then the
at
E
change
and
A-
in fee ars
This could account
appearing
oscillation
few hundred
surface
SSO
of
at E
relationship to the
has a
B
The oscillation
.
10 gamma
a
array current on the
the form BcxH*
of
magnetic
required
fee
in
in solar
Assuming that
order of 5 A.
meters
fluctuation
fluctuation
a
perturbed
a
drops to on
satellite
the
at
the
The concept of
gamma at ^ meters,
1
means
This
meters.
^
Ledley?
(B.
field strength
by
gamma
100
and
fields
varies
in
below
the
frequency by
The magnetic intensity would
hertz.
only have to vary at the loop antenna on the order to 6-7
gamma to
produce this change, well within our estimates.
Note again that the modulation of the solar array current
closely
matches
the
shape
the
of
plasma oscillation
(Figure IIIA-IS).
The above scenario assumes
frequency
strength at
is
determined
the
by
antenna.
the
It
45
stimulated wave
that the
local
also
magnetic field
assumed
that the
electric antenna couples in close to the satellite.
in Figure IIIA-9,
switches from
example,
for
the magnetic
electric antenna the
to the
frequency of the stimulated wave does
would
case
the
be
only
antennae coupled at the
location and
size of
is possible,
instead,
to
the
satellite
shift
same
Considering the
radius.
the antennae this is unlikely.
that the signal
first
(within
is
However, this
the plasma
in a
is
meter)
is being
and
means the
why no
switches
receiver
the
It
generated close
This would explain
when
seen
antennae.
beam interacts with
very limited range, near the satellite.
Above we assumed a perturbation field
near the satellite
100 gamma to produce a EOO-
be approximately
surface to
This
not change.
the electric and magnetic
if
"broadcast" to both antennae.
frequency
the receiver
when
that
Note
300 Hz frequency shift at S meters from the surface.
If
the beam-plasma interaction is taking place closer to the
satellite the strength of
perturbation
the
field would
have to be smaller to be consistent with the frequency of
oscillation
we
magnetic
field
satellite
a
be
the
observe.
varied
We
as
assumed
l/r® when,
satellite
the
in fact,
near the
more complicated, undetermined dependence may
controlling
magnetic field.
factor
Hence,
in
determining
the frequency
46
the
local
of any stimulated
generated
wave
point
the
at
interaction would vary depending
of
on
beam-plasma
the
local magnetic
the
field fluctuations.
We observed similar behavior over several operational
periods on this day.
No
emissions
been
have
other examples
of fee related
found
on
other
relationship between the operation
of
the
yet
plasma wave
and the
gun operation
either
satellite
couples
to
possibility
and
is
the plasma wave experiments or
repeatable
cyclotron
frequency.
This
Given
to
the
limitations
the
latter
current dependence?
relationship
the
by
satellite in
way.
suggested by the beam
discounted
The
(electron gun)
the beam interacts with the plasma near the
characteristic)
A
electron gun
spectra is consistently found.
generated interference
a
days.
electron
to
the
accuracy of the sensors (especially the magnetometer) and
location
their
observation
of
with
the
respect
stimulated
satellite,
the
to
plasma
gyrof requency can be adequately explained.
for the
but
generation of
observations
that
below the
The mechanism
has not been pursued,
the signal
suggest
wave
the
a
plasma
wave
was
stimulated at the electron gyrof requency due to operation
of the electron
gun.
This
41
would
be
consistent with
.
standard
calculations
waves (Chen,
generated
beam
of
1985)
B.
3
1^:13:00 - 1^:36:36
APRIL 1979
The initial
basis for
as electron
such a
goal was to catalogue the plethora
that are
commonly seen
and understood.
A second
basis.
of interference lines
plasma wave data so that
in the
features in
the remaining
a
The intense fee
heating.
200 provides
on Day
provide
was to
observations which had
understanding electron
been interpreted
wave seen
this thesis
intent of
the data
could be identified
Towards that goal this sections provides
examples of spectrograms taken during different
modes of
operation of the electron gun.
The
photographs
different modes of
presented
sequence
voltages.
operation
of
operations
and
gun are
arranged in
are
gun
a
current and
The lowest current setting is presented first
with the corresponding voltages
1500,
electron
the
different
at
during the
taken
photographs
The
below.
of
spectra
the
of
100
stepped
through
in
similar
settings
for
HA;
50,
150,
300, 500,
The current is then increased to
3000 volts).
10 HA and then to
(1
HA
and
sequence.
the
each
setting is
Common features between
electron
48
voltage
gun
(voltage
or
current) Bre not readily apparent.
can
be
considered
common
interference lines
the electron gun
interference
The only feature that
presence
the
is
of
the
which appear throughout the data with
on
lines
does
appearance
The
off.
or
appear
not
to be tied
of the
to any
particular setting of the electron gun parameters and may
most likely be a function of the setting of the automatic
gain control of the
identify
will
receiver.
descriptions below
The
those signals that are common interference
characteristics
unique
lines and any particular
of the
plasma wave data.
gun operations
The electron
during this period were
designed to determine the effect the various gun modes of
operation had on the plasma wave data.
at L7.25
local
magnetic latitude
time.
The
range of energies
setting
was
100
of -17
The satellite was
degrees and midnight
electron beam was operated over
and
HA
currents.
due
to
Gusshoven,
et
wide
maximum current
The
the detrimental effects on
other instruments on the satellite noted
experiments.
a
al
,
during previous
(1987)
reported the
effects of electron gun operations on spacecraft charging
during experiments
1983
which
experiments.
were
on Day 90,
similar
in
1979 and Days 312 and 313,
nature
to
the
Day
93
The electron gyrof requency was near ^.2 kHz
49
»
during
this
time
1987).
A
summary
Private communicat ions
Ledley,
(B.
of the SCA^-1 experiment commands is
included in Table III.
The first set of figures show the typical plasma wave
The spectrograms shown
characteristics with the gun off.
are grey
vertical axis
axis
presentations
scale
scale
spectrograms
is
frequency
different
is
due
to
proportional to
white
being
highest.
related
the
from
lowest
to
satellite
previous
The
of the grey scale,
amplitude,
systems
In Figure
being
black
the
ambient
or
in
the
IIIB-1 the spectrum prior to the
Figure IIIB-E
be seen.
line plot of the magnetic receiver spectra during
the time the gun is off.
tuning
the
of
receiver mode.)
the intensity
SC^-1 power being turned on can
data are
(The vertical
The signals that are present are those that are
environment.
is the
that
data. The
The amplitude of the signals in
horizontal axis is time.
DB is
from 0-6 kHz.
different
a
radio
the
of
Present
in the
magnetic field
the 700 Hz tuning fork and the l-^OO and ElOO Hz
fork
interference
interference
harmonic
lines
were
(Day EGO) of this thesis.
seen faintly.
Also
approximately 3 kHz.
discussed
The 1^00
present is
Receiver
SO
lines.
These
in the
Chapter IIIA
Hz line
can only be
an interference line at
noise
characterizes the
^j52:^aauAjj.Q_vo^it^
•gun- off...
/y-^r,;-?;.
,;%•
-
v-.-^»j^^j^^0^5?^,§i^|^
Figure IIIB-1. Beam on at 14:14:04, 10 yA, 50
volts
,
51
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remaining distinctive
feature in
signals are present only
in the
the-
being
Apparently
generated
absence
interference
probably low
electric
the
in
essentially void of
a.r
lines are
other experiments on the satellite.
by
The signal strength is
their
these
These
magnetic receiver data.
The electric receiver spectrograms
any signals.
spectrogram.
which would explain
Turning on the
data.
electron gun system power at 1^:13:3^ did not
affect the
characteristic of the plasma wave data.
Returning
to
Figure
IIIB-lj
there was an immediate
effect on the plasma wave data when the electron beam was
activated at
l^rl-^iO^ at
10 HA,
50 volts.
fork interference lines are masked and
2745 Hz
frequency is well below
this period.
300 Hz
another signal at
spectrum analyzer)
(measured on
electron
the
The tuning
appears.
This
gyrof requency for
This signal appears to have approximately a
bandwidth
in
appears monochromatic
magnetic
the
receiver
electric field
in the
data, but
The
data.
signal is probably monochromatic in both receivers and is
being
"smeared"
in
the
magnetic
receiver data due to
receiver gain.
Figure IIIB-3
shows the
changes to
the plasma wave
data as the beam parameters are stepped through the
50,
150 and 300 volt modes.
1
HA;
The beam current was reduced
53
^^^^JV
v^T*
.
-^-r- - ^-:. .'J:^-'. -r«.- '--^ -^i^'--
50 volts-
—1 UA.
10 yA^ 5Q vQlta ^k
<
--^-/^^^ii^\<; >'^^**^j£t^ ^-^^^r^-^^
y.as^^;
Beam to
(a)
<
1 -PA,
(b)
50 volts
UA,
1
^
50 voltsr
Beam to
yA,
1
Beam to
1
yA,
1
uA,.
I
II
volts->
150 ',j.w^)
-fj.
'
150 volts at 14:15:43.
1
(c)
at 14:14:34.
300 volts-
uA,
300 volts'at 14:17:09.
Figure IIIB-3. Spectrograms for beam current of
1 yA; 50, 150 and 300 volts.
54
to
Broadband receiver
HA at l^il-^rS^ (Figure IIIB-3a).
1
noise between 500-E500
No signals
data.
energy
beam
the magnetic
in
interference line
3 kHz
A
broadband signal from 700-2100 Hz is
feature in the magnetic data.
the dominant
data is essentially
is masked.
increased to 150 volts at 14:15:^-3
is
(Figure IIIB-3b).
present
is
are seen in the electric data and the
tuning fork and the
The
Hz
featureless.
The electric
energy is
beam
The
increased to 300 volts at 1-^:17:09 (Figure IIIB-3c).
plasma wave characteristics ^re
essentially the
The
same as
those at 150 volts.
Figure IIIB-A- shows the change in the characteristics
of the plasma wave data as the gun is stepped through the
1
HA;
1500 and 3000 volt modes.
500,
increased to
Figure
500
IIIB-5
volts
shows
receiver data at the
1
14:18:19
at
line
the
HA,
The beam energy is
(Figure IIIB—^a).
plot
of
the
500 volts setting.
magnetic
The 700 Hz
tuning fork interference line is very strong and the ElOO
Hz
and the 3 kHz
be seen
lines can
faintly.
Receiver
noise dominates the rest of the spectrum and is strongest
around
1
seen that
kHz.
the interference
the mode change.
Figure IIIB-A-a,
Returning to
When the
it
can be
lines are more evident after
beam energy
is
increased to
1500 volts, Figure IIlB-'^b shows no significant change to
55
.
I
i
uA,
3QQ vol^a
Beam to
(a)
1
UA,
.5
1
1
(c)
U A.
1
yA, ,1500 volts.
uA/ 1500 volts at 14:19:44.
1
voltsr^
15 -QQ.
Beam to
^^^ volts
500 volts at 14:18:19
0^ volts-
Beam to
(b)
UA,
^ '^^^
)k
1
vA,
1
uA,
3000 volts.
3000 volts at 14:21:02.
Figure IIIB-4. Spectrograms for beam current of
(Arrow indicates
1 uA; 500, 1500 and 3000 volts.
time of line plot)
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en
m c
•H
iH
C
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c
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57
<•
Sh
the plasma wave data.
volts
3000
to
14:21:02 (Figure IIIB-4c), the lower
at
limit of the broadband signal seen
shifts down
frequency
in
1
specific
hA beam
line is more distinct.
operations did
interference
not result
presumably
affected,
satellite AGC
since
1
HA
less
is
than
modification
naturally
the
electron
of
the
occurring
current,
and
current by a substantial fraction (1-
The next current level up,
natural
the
satellite line
3 kHz
by
ambient
current,
secondary emission
the
of
This is consistent with our expectations,
.
photoemission
10*/.).
in any gun
reception
The
lines.
700/2100 Hz tuning fork lines, and
were
magnetic data
in the
from about 700 Hz to about 500
Hz and the 2100 Hz tuning fork
The
energy is increased
When the beam
currents,
10 HA,
will
and
is
comparable to
perturb the satellite
system substantially.
Figure IIIB-6 shows the effect the gun operations had
at
hA on
10
the plasma
Figure IIIB-6 shows
wave data.
the plasma wave data while the gun was operated in the 10
HA;
new
50,
150 and 300 volt modes.
interference
communication,
lines
1987)
are
A substantial
Koons
found.
suggested that
a
responsible
for
some
of
58
the
(private
voltage controlled
oscillator that is part of SC^ or another
be
variety of
experiment may
interference
lines
uA,
'1
Beam to 10
(a)
MA,
•10
IQ
liA,
5
volts-
50 volts at 14:22:27.
]xA,
50 volts
10 VA,
150 volts.
Beam to 10 yA, 150 volts at 14:23:36.
(b)
4-10.
Volts*
,5 Q.
MA,
SWr-*;-
150-
^
volts
-"^"*'-f,'
.-
•10
300 volts
yA,
;'
-'='^7"'
'
'-
(c)
Beam to 10 yA,
300 volts at 14:24:47.
Figure IIIB-6. Spectrograms for beam current of
10 yA; 50, 150 and 300 volts.
59
There is some evidence
observed.
tends to
IIIB-6 that
current is
frequency.
line
be the
It
3130 Hz appears in the
This
data.
3 kHz
energy is increased to 150
first
at
the "3 kHz"
however, that
distinct.
and
signal
interference line, shifted in
is shown below,
separate
is
at
The 700
previously are
seen
lines
signal
electric
and
appeared to
interference
strong
and a
magnetic
the beam
1^:EE:27
increased to 10 HA (Figure IIIB-6a).
Hz and 2100 Hz
masked
The beam
support this contention.
is reduced to 50 volts and at
voltage
data of Figure
in the
volts
l'^:E3:36 the beam
At
(Figure
IIIB-6b).
signal now appears in the magnetic data at 3715 Hz.
A
This
signal is broadband (approximately a 500 Hz bandwidth)
the
magnetic
monochromatic
and
in
in
the electric data.
This difference in width again reflects the difference in
receiver
gain,
magnetic
antenna
potential
increases
volts (Olsen,
and is
It
also
but
to
the
reflects the proximity of the
spacecraft.
slightly at
1987).
The
this point
This particular
to about 30
signal is unique
not identifiable with any previously seen signal.
appears to be related to this particular
of the electron gun.
in
the
mode setting
The beam energy is increased to 300
volts at 1^:E^:^7 (Figure
increase
satellite
IIIB-6c) with
spacecraft
60
potential.
a
corresponding
The
3
kHz
interference line is now present along
with the
STA'S Hz
line.
This discounts the 3745 Hz line being a variation
of the
3
affected
line
kHz
oscillator and
by
voltage controlled
a
indeed indicates that the 3 kHz line from
the satellite
is
unique aspect
of the signals seen at 3130, 3715 and 3745
not
varying
Another
frequency.
in
Hz in the 10 HA; 50,
150 and 300 volt modes is that these
signals
in
were
receiver
seen
both
broadband
data,
the electric.
lines previously
identified
featureless.
modes is
the
Evidently, the
were
present
only
signal particular
Observations
antenna.
data (not
The common interference
in the
these
to
allowing it to be propagated to
much stronger,
plasma wave
and
electric spectra was essentially
and the
electric
magnetic
the
in
monochromatic in
magnetic data,
magnetic and electric
the
of
other SCATHA
shown) confirmed that this signal
appears to be unique to these particular gun parameters.
Figure IIIB-7 shows the plasma wave
HA;
500,
1500 and 3000 volt settings.
data for
the 10
The beam energy is
increased to 500 volts at 14:25:58 (Figure IIIB-7a) while
the
receiver
electric data
was
is
tuned
still
the electric antenna.
to
essentially
featureless,
The
but
a
significant change is noted in the magnetic data from the
previous
mode.
When
receiver
the
61
switches
to
the
.
^^r'^-iSi-
.V-'
UA,
•10
1^
-'^-N
500 volts-
'.v-
•a;'^?^^^
azkH
,«
Beam to 10 yA, 500 volts at 14:25:58
(a)
-10
yA,
10 yA,
500 v-*—
1500 volts.
l:^T0^t
*-
(b)
-10
(c)
._..:%•>-
.
r-w
---.'-.;^-r/.
Beam to 10 yA, 1500 volts at 14:27:07.
yA,. 15-00
volts
10
UA,
3000 volts-
Beam to 10 yA, 3000 volts at 14:28:29.
Figure IIIB-7. Spectrograms for beam current of
10 yA; 500, 1500 and 3000 volts. (Arrow indicates
time of line plot)
62
antenna
magnetic
again present.
the
tuning
and 3 kHz lines are
fork
(approximately
broadband signal
A
bandwidth) centered at ^ kHz is also seen.
shows the
details
magnetic data
kHz
of
the
during this
lines ars clearly seen.
most dominant feature.
time.
Figure IIIB-8
spectrum
frequency
for the
The tuning fork and 3
The signal
kHz
at 4
700 and 3100 Hz becomes the main feature
The
signal
be lower
in the magnetic
seen previously at
disappeared and the 700 Hz and
appear to
volts at
IIIB-7b) and a broadband signal between
1^:S7:07 (Figure
spectrogram.
is the
An unknown signal also appears at
The beam voltage is increased to 1500
5800 Hz.
kHz
1
3 kHz
A-
kHz has
interference lines
and upper cutoff frequencies for the
The nature
signal in the magnetic data.
of this signal
is characteristic of receiver noise and may be the result
of the gain control setting of the receiver.
(Figure
volts.
IIIB-7c)
the
At
energy is increased to 3000
beam
The magnetic receiver noise changes from
kHz signal to a lower bandwidth centered near
The
higher
voltage
experiments resulted in
(500-3000
significantly
V),
a
0.5-3
1S50 Hz.
10
HA
beam
different results
The distinction between the
than lower voltage settings.
two categories exists for two reasons.
voltage settings,
l'^:ES:29
First,
at higher
the bulk of the beam probably escapes,
63
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.
since the beam energy
satellite potentials,
much
so
is
larger
ignores the possibility of
(This
inducing large differential potentials,
does not
occur at
this time.)
density, current and voltage
density
-Jenergy
x
density.
distribution
are
function
(I
oc
Area
x
energy means decreasing
on
(bump
since the beam
related
perturbation of
Hence, the
which apparently
Second,
increasing
),
than induced
significant, as it moves out the
the local electron
becomes
tail)
tail, and
less
decreases in
magni tude
Figure IIIB-9 deals with the gun operation in the 100
HA;
50,
150 and 300
reduced to
together.
50 volts;
At
is increased
at
this
volt
l'^:29:'^l
to
initial
emissions can
modes.
energy is
the 3.0 and 3.1 kHz lines reappear
(Figure IIIB-9a)
100 HA.
No
the beam current
interference lines ars found
setting.
be seen
beam
The
At
faint natural
14:E9:'^5
electric field
in the
data.
At
1^:29:59 when the receiver is again tuned to the magnetic
antenna a
broadband signal is observed.
this signal the
700,
distinguished.
At
2100
1^:30:08
3000
and
a
Superimposed on
Hz
magnetic
taken at
a
antenna
2
seconds in
Figure IIIB-10, which was
data.
slightly earlier
can be
strong (probably natural)
signal at ^-^80 Hz is seen for approximately
the
lines
time
65
than
shown
in Figure
^
•la UA, .50 volts-
UA,
-100
50 volts-
^r/- ;,>.t^r j:'r4;.^ll^4r/r>i--a:::i5;-JftS^
-
:5^«j<^isM?S^^^5?jt«-"-&
(a)
kHzM
yA,
50 volts
100 yA,
^K
150 volts-^
Beam to 100 yA, 150 volts at 14:30:42.
.00
UA,.
:''3r',**r'^r?r-(~-r^? .'
(c)
3.0
Beam to 100 yA, 50 volts at 14:29:41.
^—100
(b)
fe
ISO volts
—^.^
-
-.
.
-.--
-
—-—...
100 yA,
ik
i- ttT-
ii
i
i
nm" mim t¥ -r t
i
m
300 volts
^—i^b m^h
i
Beam to 100 yA, 300 volts at 14:31:52
Figure IIIB-9. Spectrogram for beam current of
100 yA; 50, 150, and 300 volts. (Arrows indicate
times of line plots).
66
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fi
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00
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(U
>
OQ
•H
0)
•
U N
0)
U
IE
O
O
00
•H
'3'
-P
^
(U
q
C
-P
&«
(0
10
cvj
atural
-10.
o
pa
c
III
(probably
Figure
(ap)
aanindwv
3Aiiv-i3a
67
.
shows
IIIB-9b>
likely
signal is most
(fce=^SOO Hz)
spectrum
the
frequencies may
change.
IIIB-9b).
signal
A
harmonics at 2700,
persists
signal
-^050 and
the
electric and magnetic
^-^.5
The
11).
intense
rapidly
varying
spectra
measured
spectrum.
at
Hz.
Hz
This
be seen.
spectrograms
(Figure IIIB-
attributed
electron
to
seen superimposed
lines.
Figure
1^:31:'^5.
on the
snapshot of the
A
shows
IIIB-12,
the
The strongest amplitude
a
weak signal at
These signals appear to be a fundamental
frequency at 1380 Hz and its first three
^110
with
Hz
few minutes in both the
frequencies are at 1380, 2730, ^110 and
about 5*^80
1350
next
signal
interference
(Figure
l-^-rSOi^E
Hz can
gyrof requency emissions can be
more
The beam
5-^00
field
kHz
at
approximately
at
for
volts
just
spectrum at lower
The broad
150
to
3/S fee,
naturally occurring.
also be
energy is increased
occurring
in Figure IIIB-9b
seen again
and is
prior to the mode
naturally
a
This
line plot form.
in
signal
is
at
harmonics.
The
to
the electron
150 V data as a
result of a
very
or
near
gyrof requency
We interpret the 100 HA,
strong
signal
at
1300-1500 Hz, and harmonics generated
within the receiver system.
prevent
this,
but
the
The
response
fi8
AGC
we
should nominally
observe
here
is
"<';y^ v:» »^i"JS'-'^3*r^u » M'W ;*.-^t'-M^^,fwr^^
'
u
m wp
n a'nuMUL.'tu.: 4^.**w>
Figure IIIB-ll. Plasma wave harmonic structure.
Spectrogram taken at 14:31:12. Gun is on at 100
UA, 500 volts.
fi9
o
O
-H in
c fH
o
1-
g
M
<
(0
p.
^
(U
•.
o
o
J5 iH
+J
o
+J
y-i
(TJ
c
g
3
o
0»
t-i
m
4J
•H
O
V S
3
a
(0
(0
<u
^
>1
o
in
c
<u
s^
3 p
cr o
M
X
o
u
c
t
>-
o
z
Ui
z>
(U
(U
s^
iH
IH
u
S-l
•
(1)
o
>
0>
<u
CQ
H
u
o
cu
UI
u
1
M
M
M
cr
o
•H
+J
(1)
c
CP
0)
u
3
en
•H
b
CO
2
c
•H
•
CM
c
t-i
<u
1
0)
CQ
H
M
M
w
<u
s^
d
<U
+J
h U
3 3
CP M
(SP)
aanindwv BAiiviaa
70
•
03
-P
r-l
•H
-P
b
M >
»
characteristic of an overdriven
to be "fee"
linesj
independent of the interference linesi
distinguishable because they are
frequency.
There appear
receiver.
wildly in
varying
not
This latter variation may be associated with
satellite spin, but the mode does not last long enough to
determine this.
Returning
Figure
to
increased to 300 volts
signal
and
However?
IIIB-9C shows
Hz
range
a broad
monochromatic signal
line
few times
effect.
Unlike the
in beam
does
not
stimulated
have
resonance
monochromatic
"^EOO Hz
Figure IIIB-l*^
well
This was one of the
of
the
,
this low
the gyrof requency
interpretation
plasma.
as
a
Also,
a
line (i.e. fee) appears.
completes the gun parameter sequence.
Shown are the spectrograms for the 100 HA;
300 volt
to have any
for Day EOO
below
obvious
an
The
change in
a
focus seemed
fee inferred
fundamental frequency is
and
result of
low to medium.
the change
occupied.
harmonics reappeared for a
and its
focus from
in Figure
data
spectrum centered in the 1000-1500
few seconds (Figure IIIB-13) as a
the beam
from the electric
magnetic
interference
the
is
and the interference
disappear
the
energy
beam
the
1*^:31:52
at
harmonics
its
receiver data.
IIIB-9c
settings of
the electron
11
500,
1500 and
gun beam parameters.
low fOCUS'
-?k
medium focus-
Figure IIIB-13. Spectrogram of focus change from
low to medium at 14:32:30 for beam current of
100 uA and beam voltage of 300 volts.
72
-lOQ pA,
f:
.5
a volta
;>tt&'^;-£:J3t*^-»^'''^'t^"-V'-
g^ff^
Beam to 100 uA, 500 volts at 14:33:05.
(a)
(b)
<—100
.
UA,
1500 volts—4e
-.v-;^:-» ^*>:-»-.- .-«.,
(c)
1500 volts-^
Beam to 100 vA, 1500 volts at 14:34:18
-
..
100 UA,
500 volts
100 PA,
..
vv^^----..r.-^-r.^v^o5y:.;:Tv
100 UA,
3000 volt!
>u ^, itwtwjge;B»^jpj;|ffgpjjiBpp
i
»
Beam to 100 uA, 3000 volts at 14:35:28.
Figure IIIB-14, Spectrograms for beam current of
100 uA; 500, 1500 and 3000 volts.
73
At
1^:33:05 the beam energy
(Figure
setting
This
IIIB-1'^a).
increased
is
500 volts
to
produces
a
diffuse
background in the magnetic data and the tuning fork and
interference
kHz
Sporadic signals
distinguishable.
again
are
lines
1^:33:10 and
appear at
3
at
1^:33:50 at
1100 Hz which may be related to the harmonic signals seen
earlier.
The beam energy is
14:3'^:18
(Figure
1500 volts at
increased to
A
IIIB-1'^b).
diffuse
background
characterized the spectrogram between 700 to 5000 Hz with
intensity signals
the maximum
Hz.
At l'^:35:ES
increased
to
(Figure
3000
appears to become
the
IIIB-l-^c)
energy is
beam
The 3 kHz interference line
volts.
the
centered at 2100 and 3000
cutoff
upper
frequency
for the
broadband spectra in the magnetic data.
The magnetic and
The beam is turned off at 1<^:36:30.
spectra
electric
character.
return
their
to
pre-gun
operation
The tuning fork and 3 kHz interference lines
are again the dominant feature in the spectrogram.
It
has been shown that the gun operation
plasma wave
data by noting the one to one correspondence
the change to the
gun parameters
the plasma wave data.
1-^00 Hz,
has on
the changes in
These effects vary but some common
features have been identified.
700 Hz,
affects the
The interference lines at
2100 Hz and 3 kHz are common features.
74
They do not appear to be
of the
data.
any particular setting
tied to
do appear only in the magnetic receiver
gun, but
indicate that
This would
the intensity
of these
interference lines is very low and they are not sensed by
These interference lines come from
the electric antenna.
other
experiments
the satellite.
on
Accordingly, they
can usually be eliminated as features so that
other more
interesting, natural signals in the data can be studied.
signals
The
observed at the 10 HA; 50,
to have
3715
3130,
at
on and
voltage
Koons,
package.
related
that
1987)
to
a
oscillator
frequency
in
change
These signals may be linked
in
signal may be
of the
the oscillator frequency as a
Another characteristic
result of the gun voltage change.
of this
suggested by
(as
part of the satellite experiment
is
The change
They are only
particular settings of
in the
controlled
that were
modes appear
150 and 300 volt
the electron gun parameters.
a
37-^5 Hz
been generated by the gun itself.
seen with the gun
to
and
signal was that it appeared in both the electric
and magnetic field
data.
In
other
modes
the common
signals ars seen only in the magnetic data.
The
harmonic
structure
seen
at
setting also appears to be gun related.
in
both
the
magnetic
the 100 HA current
It
too appeared
and electric receiver data.
75
The
signal appeared to be
spin modulated?
but the
data are
insufficient to be certain at this point.
During
the
sequencing
electron beam focus was
focus changes
data.
of
the
gun parameters, the
Generally, the
changed.
also
had little or no effect on the plasma wave
Figure IIIB-13 showed one example where
the focus
change did induce an effect on the plasma wave data.
The
most significant change noted to the plasma wave data was
enhancement of
already present
signals.
Figure IIIB-15
shows an example of a change in focus from medium to high
(1
50 volts).
HA,
Note that only the intensities of the
interference lines increases, no new or different signals
are seen.
This section has provided samples of plasma wave data
of operation
taken during various modes
gun.
These examples can be used for future comparison to
during
data taken
experiments.
be
used
electron
similar
These samples
satellite environment at
must
of the electron
when
a
gun
were taken
operations or
in a particular
particular altitude so caution
extrapolating
examples to other data.
76
comparisons of these
high focus
Figure IIIB-15. Spectrogram of focus change from
medium to high at 14:15:05 for beam current of
1 liA and beam voltage of 50 volts.
77
C.
OTHER OBSERVATIONS
mode
The 10 HA
operation
of
most physically
provided the
were observed.
The
obvious resonant
electron gan
the
significant emissions that
mode
HA
1
of
emissions.
did
stimulate any
not
The 100
HA mode generally
overwhelmed the plasma wave data with receiver noise.
rare occasions (e.g. Figure IIIA-7)
On
100 HA data resembled
This section will discuss three additional
gun off data.
periods when electron gun operations were conducted} with
an emphasis on the plasma wave
data taken
at the
10 HA
current setting.
On Day
111,
April 1979, between 0815 and 0838 UT
21
the satellite was at L6 6
.
degree and
plasma
in eclipse.
wave
presence
was
data
the
of
3
mean
,
With
magnetic latitude
the electron
typically
line
structure (including driven harmonics).
turned
on
appeared.
at
10
HA,
50
The new line was
than previously
a new
150
monochromatic
behavior is similar to that seen on Day
6).
The emissions
in frequency
2900 Hz).
Beam
resulted
in a
at 3.7 kHz.
This
volts
emission
other
line -near 3 kHz
slightly lower
HA,
and
by the
When the fun was
observed (approximately
parameter settings of 10
corresponding
volts
gun off the
characterized
interference
kHz
of -1
93 (Figure IIIB-
seen at 2.9 and 3.7 kHz are possibly
7g
same
the
Chapter
1 1
the
parameters,
volts
50
discussed
as
in
The differences in frequency that are seen
IB.
for the same gun
for
observed,
previously
pair
setting,
vice 3100 Hz
S900 Hz
i.e.
be due to temperature
may
sensitive oscillators which cool in eclipse.
On Day
2^ April
11-4,
the electron
The satellite was in eclipse, at L6 8 and
.
latitude
of
The gun operations on
degree.
1
this day for this mode have been discussed
Koons and
and 07^2 UT
operated briefly at the 100 HA, 50
gun was
volts setting.
magnetic
between 0735
1979,
Cohen (1982).
previously by
3.0 kHz interference line
The
was present in the magnetic receiver data with the gun on
at
100
3.1 kHz
volts.
150
hA,
line is observed.
responding
are
magnetic antenna
is seeing
seen independent of the
sees
only
Clear
switching indicate
with antenna
in space,
electric receiver data
In the
the
gun
to
changes
in
a
frequency
the antennae, separated
different
signals.
The
the satellite generated line
gun, while
the electric antenna
generated (or coupled)
line.
Later
that same day electron gun operations were conducted with
the satellite
in sunlight.
present at the 10 HA,
2400 Hz
The
3.7 kHz line was again
150 volt setting.
One
new line at
was seen when the gun was operated in the 10 HA,
50 volts mode.
79
additional
These
observations
demonstrated
the
consistent presence of monochromatic emissions induced by
the
gun
when
operated
the
in
particularly 50 and 150 volts.
to an output
frequency
shift
lower
voltage
modes,
They appear to be related
in
a
voltage controlled
oscillator associated with the electron gun.
Table IV contains a summary of the distinct emissions
seen in the plasma
emissions that
wave
could be
data
examined
to
date.
The
identified as monochromatic and
generally repeatable are tabulated by gun parameters.
80
CONCLUSIONS
IV.
The operation
predictable
of the
effects
plasma
the
on
had definite and
electron gun
wave
The
data.
following was observed:
(a)
200
the
electron
gun
emission
at
the
electron
gyrof requency
operated
at
10
On
Day
naturally
resembled
the same period.
of
the
between
This
is
the
when
occurring fee waves during
Fluctuations in
current
signal
the
an
This signal
volts.
50
correlated
signal
and solar array
that
HA,
stimulated
is
consistent
with satellite spin
variations,
and shows
result of interactions
a
electron
the frequency
beam
local plasma.
and
with inferences of ambient
electron heating due to the beam (Olsen, 1986).
(b)
The results of operation of the
50
off,
on
similar
were
volts-
Day
to
This
200.
gun at
100 HA,
those with the gun
means
there
is
a
density/energy effect on wave growth.
(c)
On
other
days,
the
couples electron gun
the
plasma
wave
gun
operation apparently
generated
interference to
instruments,
independently of
81
characteristics.
plasma
local
characteristics
of
wave data were
plasma
the
presented for the operation of the
at
different
The
electron gun
Common features can
parameters.
be identified for comparison to future data:
(1)
interference
The
oscillator
fork
tuning
generated
lines
700
at
2100 Hz are routinely seen in
by the
1^00 and
j
the magnetic
receiver data.
(2)
Operation of the electron gun tends to mask
reception
the
tuning
the
of
fork
interference lines.
(3)
A
satellite
3 kHz
generated interference line at
commonly seen,
is
independent
of the
setting of the electron gun.
(^)
Operation of the electron gun at 10 HA; 50?
generates
150 and 300 volts
probably
most
has
a
source in a voltage
electron gun.
controlled oscillator in the
It
is
possible
circuits in the
that
signal that
a
coupling
satellite
is
to
other
enhanced by
the beam.
(5)
Higher voltage
settings at
10 HA resulted
in significantly different features.
82
Broad
.
diffuse
spectra
were
seen
instead
of
monochromatic spectra.
(6)
Changes
generally
that
beam
focus
only to enhance emissions
acted
were
electron
the
in
already
present.
No
new
interference lines were generated.
The samples
of the plasma wave data taken during the
various modes of operation of
compare with
used to
more
data
understanding
are
gun
can be
data from similar experiments.
collected
of
electron
the
beam-plasma
better
compiled,
and
As
interactions
can
be
real i zed
Implications of this work
for use
of electron beams
for satellite charge control are:
(a)
electron beam changes the electron density
(b)
stimulated waves
generate electron transport so
that changes to the net current to and
satellite is
by
adding
not what
the
electron beam
would be expected simply
electron
may not,
satel lite.
83
from the
beam
in fact,
effects.
The
escape from the
APPENDIX
TABLE
I.
P7a-2
(SCATHA) EXPERIMENT
IDENTIFICATION
TITLE
SCI
Engineering Experiment
Plus VLF and HP Receivers
SC2
Spacecraft Sheath Fields
Plus Energetic Ions
SC3
High Energy Particle
Spectrometer
Satellite Electron
SCA-
And Positive Ion Beam System
SC5
Rapid Scan Particle Detector
SC6
Thermal Plasma Analyzer
SC7
Light Ion Mass Spectrometer
SC8
Energetic Ion Composition
Experiment
SC9
UCSD Charged Particle
Exper iment
SCIO
Electric Field Detector
SCI
Magnetic Field Monitor
1
ML12
Spacecraft Contamination
Plus Thermal Control
Materials Monitoring
TPM
Transient Pulse Monitor
ft4
TABLE
Day 201
I I
20 JUL 79
TIME
22:53:^0
22:5^:5^
22:55:00
22:55:37
23:02:28
23:03: 15
23:07:^1
23: 18:31
23:21 :3^
23:21 :58
23:23:^8
23:26:03
SC^-1 COMMAND
Init Lalize and Dff
1
System On
Beam On
Beam Current to 10 HA
Beam Current to 100 HA
Beam Current to 10 HA
Beam Off
Beam On 10 HA
Beam Current to 100 HA
Beam Current to 10 HA
Beam Off
System Init. and Off
&5
TABLE III
DAY 93
3
APR 79
SC^-1 COMMAND
TIME
14 13:24
1-^
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
13:34
14:04
14:34
15:05
15:34
15 143
00
17:
17 !09
39
17i
18 ;09
18; 19
19: ;03
19; 33
19: ;44
20; 26
21: ;03
21 31
22 10
22; 19
22 ;27
;
I
14:23; 20
14:23 36
14:24; 38
I
14:24 i47
14:25: 17
14:25:47
14:25:58
14
14
14
14
26 27
26: 57
27 07
27; 47
14:28:20
14:28:29
14:28:57
14:29 29
14:29 41
14:30 12
14:30 42
14:31 12
14:31 42
14:31 52
:
:
0.01 MA Beam Current
Power On
Beam On
1
HA, 50 V, M
Focus to High
Focus to Low
Increase Voltage to 150 V
Focus to High
Increase Voltage to 300 V
Focus to Med
Focus to Low
Increase Voltage to 500 V
Focus to Med
Focus to High
Increase Voltage to 1500 V
Focus to Med
Increase Beam Energy to 3000 V
Focus to High
Focus to Med
Beam Energy to 50 V
Beam Current to 10 HA
Focus to High
Beam Voltage to 150 V
Focus to Low
Beam Voltage to 300 V
Focus to Med
Focus to High
Beam Voltage to 500 V
Focus to Med
Focus to Low
Beam Voltage to 1500 V
Focus to Med
Focus to High
Beam Energy to 3000 V
Focus to Med
Beam Voltage to 50 V
Beam Current to 100 HA
Focus to High
Beam Voltage to 150 V
Focus to Med
Focus to Low
Beam Voltage to 300 V
86
1^:32:30
1<^:32:56
1^^:33:05
l'^:33:38
1^:3^^:08
1^^:3^:18
14: 3^: -^8
1*^:35:18
14:35:28
14:35:58
14:36:36
Focus to Med
Focus to High
Beam Energy to 500 V
Focus to Med
Focus to Low
Beam Energy to 1500 V
Focus to Med
Focus to High
Beam Energy to 3000 V
Focus to Med
Off
87
TABLE IV
Gun Setting
Frequencies (Hz)
off
1
HA»
700,
50 volts
150 volts
300
500
1500
3000
10 HA,
volts
volts
volts
volts
50 vo 1 ts
150 vo 1 ts
300 vo 1 ts
500 vo 1 ts
1^00, 2100, 3000
700, ElOO, 3000
700, 2100, 3000
700, 2100, 3000
2^00,
3700,
3000,
700,
^000,
27^5, 2900, 3000, 3130
37^5
3715
1^00, 2100, 3000,
5800
1500 vo 1 ts
3000 vo 1 ts
100 HA,
50
150
300
500
1500
vo 1 ts
vo 1 ts
vo 1 ts
vo 1 ts
vo 1 ts
3000 vo 1 ts
700, 2100, 3000
1350, 3100,^200
^200
700,
1-^00,
2100, 3000
;
LIST OF REFERENCES
Akai
—
K., Electron Beam
Plasma Interaction Experiment in
Space I5AS Research Note £85 The Institute of Space
and Astronaut ical Science, Komaba,
Meguro-ku, Tokyo,
Japan, undated.
»
,
,
Bernstein, W.,
H. Leinbach,
Herbert Cohen, P.S. Wilson,
T.N. Davis,
T.
Hallinan,
Baker,
Martz, R.
B.
J.
Zeimke, and W. Huber
Laboratory Observations of RF
Emissions at ^pe and n->-'/^ uMce in Electron Beam-Plasma
and
Beam-Beam Interactions
Journal of Geophysical
Research V. 80
pp. ^375-^379, 1975.
,
(
)
,
.
,
Chen, Francis F.,
Introduction to Plasma Physics and
Controlled Fusion Vol. 1, End ed
Plenum Press, New
York and London, 1985.
,
.
,
DeForest, Sherman E., Spacecraft Charging at Synchronous
Orbit, Journal of Geophysical Research
V
77
651-659,
1972.
pp.
,
.
,
"Description of
Fennell,
J.F.,
the P78-E
(SCATHA)
Satellite and Experiments", in The INS Source Book
Guide to the International Maqnetospher ic Study Data
Analysi s edited by C.T. Russell and D.J. Southwood,
p. 65, AGU, Washington, D.C., 1982.
,
Garrett, H.B., "The Charging of Spacecraft Surfaces",
Reviews of Geophysics and Space Physics V 19
pp. 577-616, November 1981.
,
.
in
,
Grard
R.,
K.
Knott, and Pedersen, Spacecraft Charging
Effects, Space Science Reviews
V. 3^
pp. 289-30-^,
,
,
,
1983.
Gussenhoven, M.S., E.G. Mullen and D.A. Hardy, Artificial
Charging of Spacecraft Due to Electron Beam Emission
presented at IEEE mtg, August 1987.
,
Kaneko, Y. Nakamura, H.
Kawashima,
N.,
Sasaki,
0.
S.
and
Kubo T. Obayashi
Miyatake, Experiments of
S.
Electron Beam from Rocket
Institute of Space and
Aeronautical Science, Tokyo, Japan, 1976.
,
,
89
Kawashima, N., and the JIKIKEN (Exos-B) CBE Project Team,
UJave Excitation in Electron Beam Experiment on
Japanese Satellite "JIKIKEN (Exos-B)"
The Institute
of Space and Aeronautical Science, Komaba, Meguro-ku,
Tokyo, Japan, undated.
,
Kawashima, N.,
S. Sasaki,
K.I. Oyama,
W.J. Raitt, P.R.
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Lowery
Survey of the Air Force
P78-2 (SCATHA) satellite
plasma wave data during
electron gun operations.
/
Thesis
L8667
c.l
Lowery
Survey of tbf^ Air Forc9.
P78-2 (SCATHA) satellite
plasma wave data during
electron gun operations.
SO»tK